Pal, S. K. (2001). Population ecology of free-ranging urban dogs in West Bengal, India. Acta Theriologica, 46(1), 69-78.
A population of urban free-ranging dogs Canis familiaris Linnaeus, 1758 was studied in Katwa, West Bengal, India. The analysis of changes in the density of the dog population over a period of 4 years revealed a considerable stability of this population. Mean (±SD)2 seasonal population density was 185±19 dogs/km2, ranging from 156 to 214 dogs/km2. A sex ratio of 1.37∶1 in favour of male was recorded in this study. High mortality (67%) occurred under the age of 4 months, and 82% mortality occurred within the age of 1 year. Among the adults, 24% mortality under the age of 2.6 year was recorded. Only a single breeding cycle and synchronization of breeding was observed. Immigration was observed as a crucial factor affecting the stability of this population.
Showing posts with label 2001. Show all posts
Showing posts with label 2001. Show all posts
Wednesday, 3 December 2014
Thursday, 6 November 2014
Dog ecology and demography in Machakos District, Kenya
Kitala, P., McDermott, J., Kyule, M., Gathuma, J., Perry, B., & Wandeler, A. (2001). Dog ecology and demography information to support the planning of rabies control in Machakos District, Kenya. Acta Tropica, 78(3), 217-230.
A study of 150 dog-owning households from six randomly selected sublocations was conducted in Machakos District, Kenya. Initially, all households were visited to collect information on dog ecology and demography based on WHO guidelines and to collect serum for rabies antibody detection. A second visit was made 1 year later, to obtain follow-up data on births, deaths, dog movements and other events since the first visit. Dog ownership was common, with a range of 53–81% (mean=63%) of households owning dogs in the six sublocations. Dog density for the five more rural sublocations ranged from 6 to 21 dogs km-2 and for the peri-urban sublocation was 110 dogs km-2. The dog population was estimated to be growing at 9% p.a. (95% C.I. 4–14%). This growth was a function of very high fecundity (1.3 females per female per year) more than compensating for high mortality, particularly among females. Life expectancy from birth was 3.5 years for males and 2.4 years for females. Half the dogs at any one time were less than 1 year of age. All dogs, by design of the study, were owned. Of these, 69% were never restricted and roamed freely to forage for food and mix with other dogs. Only a small proportion of dogs (5%) were fed commercial dog food. Most households reported observing dogs scavenging their garbage, including: their own dogs (81%), their neighbours’ dogs (75%) and unknown dogs (45%). Only 29% of dogs at least 3 months of age were reported to be vaccinated against rabies. The proportion vaccinated varied widely between sublocations (5–68%); 48% of dogs reportedly vaccinated had detectable antibodies, 31% at or above levels considered to indicate seroconversion. The proportion of dogs with detectable antibodies declined according to the time since last vaccination (55% if vaccinated ≤1 year, 47% ≤2 years and 36% >2 years); 20% of dogs reported not to have been vaccinated had detectable rabies antibody. Compared to other dog populations in rural eastern and southern Africa, Machakos District has a high density of dogs. The Machakos dog population is growing, highly dynamic, poorly supervised and inadequately vaccinated against rabies. The main implication for rabies control is that adequate vaccination coverage is unlikely to be achieved, even under optimal delivery, using the current strategy of annual vaccination of dogs older than 3 months.
Friday, 17 October 2014
The role of veterinary epidemiology in the study of free-roaming dogs and cats
Slater, M. R. (2001). The role of veterinary epidemiology in the study of free-roaming dogs and cats. Preventive veterinary medicine, 48(4), 273-286.
Free-roaming dogs or cats are domestic dogs and cats that are not confined to a yard or house. Free-roaming dogs and cats have long caused major public-health problems and animal-welfare concerns in many countries. Free-roaming dogs have been considered to be more of a problem than cats for several reasons, but the literature addressing dogs focuses primarily on their role in rabies spread and control. Free-roaming cats are becoming more of an issue in countries where free-roaming dog problems are coming under control. The change in perception of pets, beyond their value as a commodity, has also contributed to the increase in concern and attention focused on free-roaming dogs and cats. Epidemiologists have contributed much to these studies of these populations and have potential to contribute even more. The epidemiologic methods and approaches, the experience of epidemiologists in interdisciplinary teams and the importance of considering the separate sub-populations in study design and analysis all are critical in designing and evaluating interventions for free-roaming dogs and cats. In this paper, I will (1) describe a set of useful definitions regarding free-roaming dogs and cats, (2) summarize past and present topics of study in free-roaming dogs and cats, using selected examples, (3) describe the limitations of existing work and how epidemiologists might strengthen and improve this work, and (4) outline areas needing more attention by epidemiologists and why these are important.
Free-roaming dogs or cats are domestic dogs and cats that are not confined to a yard or house. Free-roaming dogs and cats have long caused major public-health problems and animal-welfare concerns in many countries. Free-roaming dogs have been considered to be more of a problem than cats for several reasons, but the literature addressing dogs focuses primarily on their role in rabies spread and control. Free-roaming cats are becoming more of an issue in countries where free-roaming dog problems are coming under control. The change in perception of pets, beyond their value as a commodity, has also contributed to the increase in concern and attention focused on free-roaming dogs and cats. Epidemiologists have contributed much to these studies of these populations and have potential to contribute even more. The epidemiologic methods and approaches, the experience of epidemiologists in interdisciplinary teams and the importance of considering the separate sub-populations in study design and analysis all are critical in designing and evaluating interventions for free-roaming dogs and cats. In this paper, I will (1) describe a set of useful definitions regarding free-roaming dogs and cats, (2) summarize past and present topics of study in free-roaming dogs and cats, using selected examples, (3) describe the limitations of existing work and how epidemiologists might strengthen and improve this work, and (4) outline areas needing more attention by epidemiologists and why these are important.
Saturday, 20 September 2014
Parasites in insular and mainland populations of feral cats
Fromont, E., Morvilliers, L., Artois, M., & Pontier, D. (2001). Parasite richness and abundance in insular and mainland feral cats: insularity or density?.Parasitology, 123(02), 143-151.
Hosts living on islands carry few parasite species, and the prevalence and intensity of directly transmitted parasites are often higher in insular than in mainland populations. However, it is unclear whether density or other features of insular populations can be responsible for the pattern observed. We compared the parasite richness, prevalence and intensity of parasites between 2 feral populations of cats living either at low density on an island (Kerguelen) or at high density on the mainland (Lyon). Parasite richness was higher in Lyon than in Kerguelen, where only Toxocara cati was found. T. cati egg prevalence was higher in Kerguelen (71·1%) than in Lyon (58·0%). Because cat density cannot explain this pattern, we propose that the low number of parasite species, the diet and/or immunity of cats act to increase prevalence in Kerguelen. Moreover, prevalence, intensity and variance-to-mean ratio increased with age and body mass in Kerguelen whereas, in Lyon, prevalence decreased with age and body mass. We hypothesize that the pattern of exposure differs between populations, and that density-dependent parasite mortality is lower in Kerguelen than in Lyon. We discuss the consequences concerning the influence of parasites on insular host populations.
Tuesday, 9 September 2014
People and dogs disturbing birds on the beach
Lafferty, K. D. (2001). Birds at a Southern California beach: seasonality, habitat use and disturbance by human activity. Biodiversity & Conservation, 10(11), 1949-1962.
Use of a Santa Barbara beach by people and birds varied in both time and space. There were 100 birds, 18 people and 2 dogs per kilometer. Bird density varied primarily with the season and tide while human activity varied most between weekend and weekday. Bird distributions along the beach were determined mainly by habitat type (particularly a lagoon and exposed rocky intertidal areas) For crows and western gulls, there was some evidence that access to urban refuse increased abundance. Interactions between birds and people often caused birds to move or fly away, particularly when people were within 20 m. During a short observation period, 10% of humans and 39% of dogs disturbed birds. More than 70% of birds flew when disturbed. Bird species varied in the frequency that they were disturbed, partially because a few bird species foraged on the upper beach where contact with people was less frequent. Most disturbances occurred low on the beach. Although disturbances caused birds to move away from humans, most displacement was short enough that variation in human activity did not alter large-scale patterns of beach use by the birds. Birds were less reactive to humans (but not dogs) when beach activity was low.
Use of a Santa Barbara beach by people and birds varied in both time and space. There were 100 birds, 18 people and 2 dogs per kilometer. Bird density varied primarily with the season and tide while human activity varied most between weekend and weekday. Bird distributions along the beach were determined mainly by habitat type (particularly a lagoon and exposed rocky intertidal areas) For crows and western gulls, there was some evidence that access to urban refuse increased abundance. Interactions between birds and people often caused birds to move or fly away, particularly when people were within 20 m. During a short observation period, 10% of humans and 39% of dogs disturbed birds. More than 70% of birds flew when disturbed. Bird species varied in the frequency that they were disturbed, partially because a few bird species foraged on the upper beach where contact with people was less frequent. Most disturbances occurred low on the beach. Although disturbances caused birds to move away from humans, most displacement was short enough that variation in human activity did not alter large-scale patterns of beach use by the birds. Birds were less reactive to humans (but not dogs) when beach activity was low.
Dogs disturbing wintering plovers
Lafferty, K. D. (2001). Disturbance to wintering western snowy plovers.Biological Conservation, 101(3), 315-325.
In order to better understand the nature of disturbances to wintering snowy plovers, I observed snowy plovers and activities that might disturb them at a beach near Devereux Slough in Santa Barbara, California, USA. Disturbance (activity that caused plovers to move or fly) to wintering populations of threatened western snowy plovers was 16 times higher at a public beach than at protected beaches. Wintering plovers reacted to disturbance at half the distance (∼40 m) as has been reported for breeding snowy plovers (∼80 m). Humans, dogs, crows and other birds were the main sources of disturbance on the public beach, and each snowy plover was disturbed, on average, once every 27 weekend min and once every 43 weekday min. Dogs off leash were a disproportionate source of disturbance. Plovers were more likely to fly from dogs, horses and crows than from humans and other shorebirds. Plovers were less abundant near trail heads. Over short time scales, plovers did not acclimate to or successfully find refuge from disturbance. Feeding rates declined with increased human activity. I used data from these observations to parameterize a model that predicted rates of disturbance given various management actions. The model found that prohibiting dogs and a 30 m buffer zone surrounding a 400 m stretch of beach provided the most protection for plovers for the least amount of impact to beach recreation.
In order to better understand the nature of disturbances to wintering snowy plovers, I observed snowy plovers and activities that might disturb them at a beach near Devereux Slough in Santa Barbara, California, USA. Disturbance (activity that caused plovers to move or fly) to wintering populations of threatened western snowy plovers was 16 times higher at a public beach than at protected beaches. Wintering plovers reacted to disturbance at half the distance (∼40 m) as has been reported for breeding snowy plovers (∼80 m). Humans, dogs, crows and other birds were the main sources of disturbance on the public beach, and each snowy plover was disturbed, on average, once every 27 weekend min and once every 43 weekday min. Dogs off leash were a disproportionate source of disturbance. Plovers were more likely to fly from dogs, horses and crows than from humans and other shorebirds. Plovers were less abundant near trail heads. Over short time scales, plovers did not acclimate to or successfully find refuge from disturbance. Feeding rates declined with increased human activity. I used data from these observations to parameterize a model that predicted rates of disturbance given various management actions. The model found that prohibiting dogs and a 30 m buffer zone surrounding a 400 m stretch of beach provided the most protection for plovers for the least amount of impact to beach recreation.
Saturday, 8 March 2014
Home range of male feral cats in Central Australia
Edwards, G. P., De Preu, N., Shakeshaft, B. J., Crealy, I. V., & Paltridge, R. M. (2001). Home range and movements of male feral cats (Felis catus) in a semiarid woodland environment in central Australia. Austral Ecology, 26(1), 93-101.
There is a paucity of data on the movement patterns of feral cats in Australia. Such data can be used to refine control strategies and improve track-based methods of monitoring populations of feral cats. In this study the home ranges and movements of male feral cats were examined over 3.5 years in a semiarid woodland environment in central Australia. Two home range estimators were used in the examination: (i) minimum convex polygon (MCP); and (ii) fixed kernel. The most widely used method of estimating home range in feral cats is MCP, while the fixed kernel method can be used to identify core areas within a home range. On the basis of the MCP method, the long-term home ranges of feral cats in central Australia were much larger than those recorded elsewhere (mean, 2210.5 ha). Twenty-four hour home ranges were much smaller (mean, 249.7 ha) and feral cats periodically shifted their 24 h ranges within the bounds of their long-term home ranges. Core area analysis indicated marked heterogeneity of space use by male feral cats. Several instances where feral cats moved large distances (up to 34 km) were recorded. These long distance movements may have been caused by nutritional stress. Using data from the literature, it is shown that prey availability is a primary determinant of long-term home range size in feral cats. The relevance of the results to the design of management strategies for feral cats in central Australia is also discussed.
There is a paucity of data on the movement patterns of feral cats in Australia. Such data can be used to refine control strategies and improve track-based methods of monitoring populations of feral cats. In this study the home ranges and movements of male feral cats were examined over 3.5 years in a semiarid woodland environment in central Australia. Two home range estimators were used in the examination: (i) minimum convex polygon (MCP); and (ii) fixed kernel. The most widely used method of estimating home range in feral cats is MCP, while the fixed kernel method can be used to identify core areas within a home range. On the basis of the MCP method, the long-term home ranges of feral cats in central Australia were much larger than those recorded elsewhere (mean, 2210.5 ha). Twenty-four hour home ranges were much smaller (mean, 249.7 ha) and feral cats periodically shifted their 24 h ranges within the bounds of their long-term home ranges. Core area analysis indicated marked heterogeneity of space use by male feral cats. Several instances where feral cats moved large distances (up to 34 km) were recorded. These long distance movements may have been caused by nutritional stress. Using data from the literature, it is shown that prey availability is a primary determinant of long-term home range size in feral cats. The relevance of the results to the design of management strategies for feral cats in central Australia is also discussed.
Thursday, 5 December 2013
Ecological restoration on Macquarie island
Copson, G., & Whinam, J. (2001). Review of ecological restoration programme on subantarctic Macquarie Island: pest management progress and future directions. Ecological Management & Restoration, 2(2), 129-138.
The establishment of exotic species of vascular flora and vertebrate fauna on subantarctic Macquarie Island since its discovery in 1810 has resulted in major changes in the biota. A management programme aims to reduce the numbers of exotic plant and animal species and assist with the recovery of pre-existing communities and processes. This paper reviews the integrated vertebrate pests management programme on Macquarie Island since 1974 and outlines future management considerations. As part of this programme, the responses of some native and exotic species of vascular flora and vertebrate fauna were monitored following control of European Rabbit (Oryctolagus cuniculus) numbers. Changes in the vegetation recorded over 10 years showed that approximately half of all the vascular species had benefited from rabbit grazing, including several which formed a major part of the rabbit’s diet. After rabbit control, some adversely affected plants responded rapidly to a reduction in grazing pressure while others will require an almost total cessation of grazing in order to re-establish their former distributions. With the decrease in rabbit numbers it was also necessary to control Feral Cats (Felis catus) due to their increased predation on native burrow-nesting birds. Feral Cat predation on introduced fauna also increased, one result of which was the eradication from the island of the introduced Weka (Gallirallus australis scotti). Reduced rabbit grazing is leading to re-establishment of the native Tall Tussock (Poa foliosa) grassland and with it the spread of the introduced Ship Rat (Rattus rattus). This review indicates that an integrated approach to pest management, with monitoring of the responses of both target and non-target species, is the most effective way to restore pre-existing communities and processes.
More on Macquarie island cats
The establishment of exotic species of vascular flora and vertebrate fauna on subantarctic Macquarie Island since its discovery in 1810 has resulted in major changes in the biota. A management programme aims to reduce the numbers of exotic plant and animal species and assist with the recovery of pre-existing communities and processes. This paper reviews the integrated vertebrate pests management programme on Macquarie Island since 1974 and outlines future management considerations. As part of this programme, the responses of some native and exotic species of vascular flora and vertebrate fauna were monitored following control of European Rabbit (Oryctolagus cuniculus) numbers. Changes in the vegetation recorded over 10 years showed that approximately half of all the vascular species had benefited from rabbit grazing, including several which formed a major part of the rabbit’s diet. After rabbit control, some adversely affected plants responded rapidly to a reduction in grazing pressure while others will require an almost total cessation of grazing in order to re-establish their former distributions. With the decrease in rabbit numbers it was also necessary to control Feral Cats (Felis catus) due to their increased predation on native burrow-nesting birds. Feral Cat predation on introduced fauna also increased, one result of which was the eradication from the island of the introduced Weka (Gallirallus australis scotti). Reduced rabbit grazing is leading to re-establishment of the native Tall Tussock (Poa foliosa) grassland and with it the spread of the introduced Ship Rat (Rattus rattus). This review indicates that an integrated approach to pest management, with monitoring of the responses of both target and non-target species, is the most effective way to restore pre-existing communities and processes.
More on Macquarie island cats
Saturday, 16 November 2013
Population dynamics and diet of feral cats and foxes in South Australia
Read, J., & Bowen, Z. (2001). Population dynamics, diet and aspects of the biology of feral cats and foxes in arid South Australia. Wildlife Research, 28(2), 195-203.
Average cat and fox densities at Roxby Downs, in northern South Australia, of 0.8 and 0.6 km-2 respectively, determined through spotlight counts over a 10-year period, probably considerably underestimate true densities. Peak rabbit populations coincided with high fox numbers, which probably suppressed cat densities. Cat abundance peaked when fox numbers were low but rabbit numbers were relatively high.
When abundant, rabbits were the principal prey of both cats and foxes. Declines in rabbits numbers coincided with dramatic declines in fox numbers. By contrast, declines in cat populations were less marked, presumably because they could more effectively switch to hunting a wide range of native vertebrates. Sand-dwelling lizards, house mice and common small passerines were the most abundant non-rabbit, vertebrate prey taken by cats. We estimate that annual cat predation accounted for approximately 700 reptiles, 150 birds and 50 native mammals per square kilometre, whereas foxes consumed on average 290 reptiles per square kilometre and few native mammals and birds in the Roxby Downs region each year.
Male cats and foxes were heavier than females. Feral cats typically weighed less than 4.0 kg, and cats weighing less than 2.5 kg typically preyed on more native vertebrates than did larger cats. Male and female cats were both typically tabby coloured, but a higher proportion of males were ginger in colour. Peak cat breeding coincided with rabbit and bird breeding and increased reptile activity during spring.
Average cat and fox densities at Roxby Downs, in northern South Australia, of 0.8 and 0.6 km-2 respectively, determined through spotlight counts over a 10-year period, probably considerably underestimate true densities. Peak rabbit populations coincided with high fox numbers, which probably suppressed cat densities. Cat abundance peaked when fox numbers were low but rabbit numbers were relatively high.
When abundant, rabbits were the principal prey of both cats and foxes. Declines in rabbits numbers coincided with dramatic declines in fox numbers. By contrast, declines in cat populations were less marked, presumably because they could more effectively switch to hunting a wide range of native vertebrates. Sand-dwelling lizards, house mice and common small passerines were the most abundant non-rabbit, vertebrate prey taken by cats. We estimate that annual cat predation accounted for approximately 700 reptiles, 150 birds and 50 native mammals per square kilometre, whereas foxes consumed on average 290 reptiles per square kilometre and few native mammals and birds in the Roxby Downs region each year.
Male cats and foxes were heavier than females. Feral cats typically weighed less than 4.0 kg, and cats weighing less than 2.5 kg typically preyed on more native vertebrates than did larger cats. Male and female cats were both typically tabby coloured, but a higher proportion of males were ginger in colour. Peak cat breeding coincided with rabbit and bird breeding and increased reptile activity during spring.
Sunday, 13 October 2013
Wednesday, 9 October 2013
Invasive species removal in whole ecosystem context
Zavaleta, E. S., Hobbs, R. J., & Mooney, H. A. (2001). Viewing invasive species removal in a whole-ecosystem context. Trends in Ecology & Evolution, 16(8), 454-459.
Eradications of invasive species often have striking positive effects on native biota. However, recent research has shown that species removal in isolation can also result in unexpected changes to other ecosystem components. These secondary effects will become more likely as numbers of interacting invaders increase in ecosystems, and as exotics in late stages of invasion eliminate native species and replace their functional roles. Food web and functional role frameworks can be used to identify ecological conditions that forecast the potential for unwanted secondary impacts. Integration of eradication into a holistic process of assessment and restoration will help safeguard against accidental, adverse effects on native ecosystems.
Eradications of invasive species often have striking positive effects on native biota. However, recent research has shown that species removal in isolation can also result in unexpected changes to other ecosystem components. These secondary effects will become more likely as numbers of interacting invaders increase in ecosystems, and as exotics in late stages of invasion eliminate native species and replace their functional roles. Food web and functional role frameworks can be used to identify ecological conditions that forecast the potential for unwanted secondary impacts. Integration of eradication into a holistic process of assessment and restoration will help safeguard against accidental, adverse effects on native ecosystems.
Sunday, 22 September 2013
Feral cat home range and habitat selection in central Australia
Edwards, G. P., De Preu, N., Shakeshaft, B. J., Crealy, I. V., & Paltridge, R. M. (2001). Home range and movements of male feral cats (Felis catus) in a semiarid woodland environment in central Australia. Austral Ecology, 26(1), 93-101.
There is a paucity of data on the movement patterns of feral cats in Australia. Such data can be used to refine control strategies and improve track-based methods of monitoring populations of feral cats. In this study the home ranges and movements of male feral cats were examined over 3.5 years in a semiarid woodland environment in central Australia. Two home range estimators were used in the examination: (i) minimum convex polygon (MCP); and (ii) fixed kernel. The most widely used method of estimating home range in feral cats is MCP, while the fixed kernel method can be used to identify core areas within a home range. On the basis of the MCP method, the long-term home ranges of feral cats in central Australia were much larger than those recorded elsewhere (mean, 2210.5 ha). Twenty-four hour home ranges were much smaller (mean, 249.7 ha) and feral cats periodically shifted their 24 h ranges within the bounds of their long-term home ranges. Core area analysis indicated marked heterogeneity of space use by male feral cats. Several instances where feral cats moved large distances (up to 34 km) were recorded. These long distance movements may have been caused by nutritional stress. Using data from the literature, it is shown that prey availability is a primary determinant of long-term home range size in feral cats. The relevance of the results to the design of management strategies for feral cats in central Australia is also discussed.
Edwards, G. P., Preu, N., Crealy, I. V., & Shakeshaft, B. J. (2002). Habitat selection by feral cats and dingoes in a semi‐arid woodland environment in central Australia. Austral Ecology, 27(1), 26-31.
Habitat use by feral cats and dingoes was examined within a heterogeneous semi-arid woodland site in central Australia over 2 years. Density estimates of feral cats based on tracks were higher in mulga habitat than in open habitat. Isodar analysis implied that this pattern of habitat use by feral cats was consistent with the consumer-resource model of density-dependent habitat selection, which is an ideal free solution. The reason why mulga supported higher densities of feral cats was unclear. Foraging success of feral cats may be higher in the mulga because the stalk and ambush hunting tactics typically employed by felids are well suited to dense cover. Mulga may also have offered feral cats more protection from dingo predation. Dingo activity was distributed uniformly across habitats. The dingo isodar was statistically non-significant, suggesting that habitat selection by dingoes was independent of density.
There is a paucity of data on the movement patterns of feral cats in Australia. Such data can be used to refine control strategies and improve track-based methods of monitoring populations of feral cats. In this study the home ranges and movements of male feral cats were examined over 3.5 years in a semiarid woodland environment in central Australia. Two home range estimators were used in the examination: (i) minimum convex polygon (MCP); and (ii) fixed kernel. The most widely used method of estimating home range in feral cats is MCP, while the fixed kernel method can be used to identify core areas within a home range. On the basis of the MCP method, the long-term home ranges of feral cats in central Australia were much larger than those recorded elsewhere (mean, 2210.5 ha). Twenty-four hour home ranges were much smaller (mean, 249.7 ha) and feral cats periodically shifted their 24 h ranges within the bounds of their long-term home ranges. Core area analysis indicated marked heterogeneity of space use by male feral cats. Several instances where feral cats moved large distances (up to 34 km) were recorded. These long distance movements may have been caused by nutritional stress. Using data from the literature, it is shown that prey availability is a primary determinant of long-term home range size in feral cats. The relevance of the results to the design of management strategies for feral cats in central Australia is also discussed.
Edwards, G. P., Preu, N., Crealy, I. V., & Shakeshaft, B. J. (2002). Habitat selection by feral cats and dingoes in a semi‐arid woodland environment in central Australia. Austral Ecology, 27(1), 26-31.
Habitat use by feral cats and dingoes was examined within a heterogeneous semi-arid woodland site in central Australia over 2 years. Density estimates of feral cats based on tracks were higher in mulga habitat than in open habitat. Isodar analysis implied that this pattern of habitat use by feral cats was consistent with the consumer-resource model of density-dependent habitat selection, which is an ideal free solution. The reason why mulga supported higher densities of feral cats was unclear. Foraging success of feral cats may be higher in the mulga because the stalk and ambush hunting tactics typically employed by felids are well suited to dense cover. Mulga may also have offered feral cats more protection from dingo predation. Dingo activity was distributed uniformly across habitats. The dingo isodar was statistically non-significant, suggesting that habitat selection by dingoes was independent of density.
Thursday, 5 September 2013
Effect of exurban growing on vertebrate abundance
Odell, E. A., & Knight, R. L. (2001). Songbird and Medium‐Sized Mammal Communities Associated with Exurban Development in Pitkin County, Colorado. Conservation Biology, 15(4), 1143-1150.
Residential development is occurring at unprecedented rates in the Rocky Mountain region of the United States, with unknown ecological consequences. We conducted our research in exurban development in Pitkin County, Colorado, between May and June in 1998 and 1999. Unlike suburban development, exurban development occurs beyond incorporated city limits, and the surrounding matrix remains the original ecosystem type. We surveyed songbirds and medium-sized mammals at 30, 180, and 330 m away from 40 homes into undeveloped land to examine the effect of houses along a distance gradient, and in developments of two different housing densities as well as undeveloped sites to examine the effect of housing density. We placed bird species into one of two groups for the house-distance effect: (1) human-adapted species, birds that occurred in higher densities close to developments and lower densities farther away and (2) human-sensitive species, birds that occurred in highest densities farthest from homes and in lowest densities close to development. For both groups, densities of individual species were statistically different between the 30- and 180-m sites. Six species were classified as human-adapted, and six were classified as human-sensitive for the house-distance effect. Dogs (Canis familiaris) and house cats ( Felis domesticus) were detected more frequently closer to homes than farther away, and red foxes ( Vulpes vulpes) and coyotes (Canis latrans) were detected more frequently farther away from houses. With respect to the effect of housing density, most avian densities did not differ significantly between high- and low-density development but were statistically different from undeveloped sites. Six species were present in higher densities in developed areas, and eight species were present in higher densities in undeveloped parcels. Similar results were found for mammalian species, with dogs and cats detected more frequently in high-density developments and red foxes and coyotes detected more frequently in undeveloped parcels of land. From an ecological standpoint, it is preferable to cluster houses and leave the undeveloped areas in open space, as opposed to dispersing houses across the entire landscape.
El desarrollo residencial esta ocurriendo en el oeste de las Montañas Rocallosas a ritmos sin precedente, con consecuencias ecológicas desconocidas. Desarrollamos nuestra investigación en un desarrollo exurbano en el Condado Pitkin, Colorado entre mayo y junio de 1998 y 1999. A diferencia del desarrollo suburbano, el desarrollo exurbano ocurre más allá de los límites de la ciudad y en la matriz que lo rodea permanece el ecosistema original. Registramos aves canoras y mamíferos pequeños a 30, 180 y 330 m de 40 casas en terrenos sin desarrollar para examinar el efecto de las casas a los largo de un gradiente de distancia, y en desarrollos con dos diferentes densidades de casas para examinar el efecto de la densidad. Colocamos a las especies de aves en uno de dos grupos para el efecto casa –distancia 1) especies adaptadas al humano, aves con la mayor densidad cerca de los desarrollos urbanos y menor densidad lejos de ellos y 2) especies sensibles al humano, aves que ocurrían con la mayor densidad lejos de los hogares y menor densidad cerca del desarrollo urbano. Para ambos grupos, las densidades de especies individuales fueron estadísticamente distintas en los sitios entre 30 y 180 m. Seis especies fueron clasificadas como adaptadas al humano y seis fueron clasificadas como especies sensibles al humano para el efecto casa – distancia. Se detectaron perros ( Canis familiaris) y gatos ( Felis domesticus) con mayor frecuencia cerca de las casas que lejos de ellas, y se detectaron zorros rojos ( Vulpes vulpes) y coyotes (Canis latrans) con mayor frecuencia lejos de las casas. Respecto al efecto de la densidad de casas, la mayoría de las densidades de aves no fueron significativamente diferentes entre el desarrollo de alta y baja densidad, pero fueron estadísticamente distintas de los sitios sin desarrollo. Seis especies tuvieron mayor densidad en los sitios desarrollados y ocho especies presentaron mayor densidad en las parcelas no desarrolladas. Se encontraron resultados similares para las especies de mamíferos, detectándose perros y gatos más frecuentemente en desarrollos con alta densidad; mientras que zorros rojos y coyotes fueron detectados más frecuentemente en las parcelas sin desarrollo. Desde una perspectiva ecológica, es preferible agrupar las casas y dejar las áreas sin desarrollo en espacios abiertos, y no dispersar las casas por todo el paisaje.
Residential development is occurring at unprecedented rates in the Rocky Mountain region of the United States, with unknown ecological consequences. We conducted our research in exurban development in Pitkin County, Colorado, between May and June in 1998 and 1999. Unlike suburban development, exurban development occurs beyond incorporated city limits, and the surrounding matrix remains the original ecosystem type. We surveyed songbirds and medium-sized mammals at 30, 180, and 330 m away from 40 homes into undeveloped land to examine the effect of houses along a distance gradient, and in developments of two different housing densities as well as undeveloped sites to examine the effect of housing density. We placed bird species into one of two groups for the house-distance effect: (1) human-adapted species, birds that occurred in higher densities close to developments and lower densities farther away and (2) human-sensitive species, birds that occurred in highest densities farthest from homes and in lowest densities close to development. For both groups, densities of individual species were statistically different between the 30- and 180-m sites. Six species were classified as human-adapted, and six were classified as human-sensitive for the house-distance effect. Dogs (Canis familiaris) and house cats ( Felis domesticus) were detected more frequently closer to homes than farther away, and red foxes ( Vulpes vulpes) and coyotes (Canis latrans) were detected more frequently farther away from houses. With respect to the effect of housing density, most avian densities did not differ significantly between high- and low-density development but were statistically different from undeveloped sites. Six species were present in higher densities in developed areas, and eight species were present in higher densities in undeveloped parcels. Similar results were found for mammalian species, with dogs and cats detected more frequently in high-density developments and red foxes and coyotes detected more frequently in undeveloped parcels of land. From an ecological standpoint, it is preferable to cluster houses and leave the undeveloped areas in open space, as opposed to dispersing houses across the entire landscape.
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El desarrollo residencial esta ocurriendo en el oeste de las Montañas Rocallosas a ritmos sin precedente, con consecuencias ecológicas desconocidas. Desarrollamos nuestra investigación en un desarrollo exurbano en el Condado Pitkin, Colorado entre mayo y junio de 1998 y 1999. A diferencia del desarrollo suburbano, el desarrollo exurbano ocurre más allá de los límites de la ciudad y en la matriz que lo rodea permanece el ecosistema original. Registramos aves canoras y mamíferos pequeños a 30, 180 y 330 m de 40 casas en terrenos sin desarrollar para examinar el efecto de las casas a los largo de un gradiente de distancia, y en desarrollos con dos diferentes densidades de casas para examinar el efecto de la densidad. Colocamos a las especies de aves en uno de dos grupos para el efecto casa –distancia 1) especies adaptadas al humano, aves con la mayor densidad cerca de los desarrollos urbanos y menor densidad lejos de ellos y 2) especies sensibles al humano, aves que ocurrían con la mayor densidad lejos de los hogares y menor densidad cerca del desarrollo urbano. Para ambos grupos, las densidades de especies individuales fueron estadísticamente distintas en los sitios entre 30 y 180 m. Seis especies fueron clasificadas como adaptadas al humano y seis fueron clasificadas como especies sensibles al humano para el efecto casa – distancia. Se detectaron perros ( Canis familiaris) y gatos ( Felis domesticus) con mayor frecuencia cerca de las casas que lejos de ellas, y se detectaron zorros rojos ( Vulpes vulpes) y coyotes (Canis latrans) con mayor frecuencia lejos de las casas. Respecto al efecto de la densidad de casas, la mayoría de las densidades de aves no fueron significativamente diferentes entre el desarrollo de alta y baja densidad, pero fueron estadísticamente distintas de los sitios sin desarrollo. Seis especies tuvieron mayor densidad en los sitios desarrollados y ocho especies presentaron mayor densidad en las parcelas no desarrolladas. Se encontraron resultados similares para las especies de mamíferos, detectándose perros y gatos más frecuentemente en desarrollos con alta densidad; mientras que zorros rojos y coyotes fueron detectados más frecuentemente en las parcelas sin desarrollo. Desde una perspectiva ecológica, es preferible agrupar las casas y dejar las áreas sin desarrollo en espacios abiertos, y no dispersar las casas por todo el paisaje.
Friday, 9 August 2013
Bird and rat numbers on Little Barrier after cat eradication
Girardet, S. A. B., Veitch, C. R., & Craig, J. L. (2001). Bird and rat numbers on Little Barrier Island, New Zealand, over the period of cat eradication 1976–80. New Zealand Journal of Zoology, 28(1), 13-29.
Passerines were monitored on Little Barrier Island over 15 years (1975–89) spanning the period (1976–80) when feral cats were eradicated from the island. All birds seen and heard were recorded while walking three transects representing an altitudinal range from near sea level to approximately 550 m above sea level. Analysis of variance statistics were used to test for differences in bird numbers between transects and between years. Bird species were examined by transect to test for changes in numbers over time. Three species had increased on some transects, and two species had decreased on some transects, but it was difficult to attribute changes in bird numbers to the one cause which we were able to study: reduced cat numbers. Examination of numbers of individuals of 14 species recorded between transects showed significant differences for some individual species, but not for all species grouped together. Four species did not show any significant differences between transects. This study demonstrates different patterns in bird distributions on Little Barrier Island which cannot be understood from these data.
Index traplines were set for Pacific rats or kiore (Rattus exulans) between 1977 and 1984, before and after cat eradication. Rat numbers fluctuated widely, and there were no significant differences that could be attributed to the changes in cat numbers.
Related articles
Passerines were monitored on Little Barrier Island over 15 years (1975–89) spanning the period (1976–80) when feral cats were eradicated from the island. All birds seen and heard were recorded while walking three transects representing an altitudinal range from near sea level to approximately 550 m above sea level. Analysis of variance statistics were used to test for differences in bird numbers between transects and between years. Bird species were examined by transect to test for changes in numbers over time. Three species had increased on some transects, and two species had decreased on some transects, but it was difficult to attribute changes in bird numbers to the one cause which we were able to study: reduced cat numbers. Examination of numbers of individuals of 14 species recorded between transects showed significant differences for some individual species, but not for all species grouped together. Four species did not show any significant differences between transects. This study demonstrates different patterns in bird distributions on Little Barrier Island which cannot be understood from these data.
Index traplines were set for Pacific rats or kiore (Rattus exulans) between 1977 and 1984, before and after cat eradication. Rat numbers fluctuated widely, and there were no significant differences that could be attributed to the changes in cat numbers.
Related articles
Eradication of cats on Little Barrier
Veitch, C. R. (2001). The eradication of feral cats (Felis catus) from Little Barrier Island, New Zealand. New Zealand Journal of Zoology, 28(1), 1-12.
Feral cats (Felis catus) probably reached Little Barrier Island in about 1870. They contributed to the total extinction of the Little Barrier snipe (Coenocorypha aucklandica barrierensis), the local extinction of North Island saddleback (Philesturnus carunculatus rufusater) and the severe reduction in numbers of grey‐faced petrel (Pterodroma macroptera gouldi), Cook's petrel (P. cookii) and black petrel (Procellaria parkinsoni), plus the decline of lizard and tuatara species.
Sporadic cat control was carried out on Little Barrier from 1897 to 1977. A determined eradication attempt commenced in July 1977 was completed on 23 June 1980. Cage traps, leg‐hold traps, dogs and 1080 poison were used, but leg‐hold traps and 1080 poison were the only effective methods. Altogether, 151 cats were known to have been killed before the eradication was declared complete. Important lessons learnt can be transferred to other feral cat eradication programmes. The responses of the bird populations are described elsewhere (Girardet et. al. 2001).
Related articles
Sporadic cat control was carried out on Little Barrier from 1897 to 1977. A determined eradication attempt commenced in July 1977 was completed on 23 June 1980. Cage traps, leg‐hold traps, dogs and 1080 poison were used, but leg‐hold traps and 1080 poison were the only effective methods. Altogether, 151 cats were known to have been killed before the eradication was declared complete. Important lessons learnt can be transferred to other feral cat eradication programmes. The responses of the bird populations are described elsewhere (Girardet et. al. 2001).
Related articles
Sunday, 9 June 2013
Feral cat's demography in New South Wales
Molsher, R. L. (2001). Trapping and demographics of feral cats (Felis catus) in central New South Wales. Wildlife Research, 28(6), 631-636.
A total of 76 feral cats (Felis catus) (29 individuals; 47 recaptures) was trapped during 6027 trap-nights using both cage and leg-hold traps from November 1994 to August 1996 at Lake Burrendong in central New South Wales. No significant difference was found in the relative capture efficiency between cage and leg-hold traps (P > 0.05). Overall capture efficiency was 1.3 cats per 100 trap-nights, although this varied seasonally, being higher in late autumn and early winter. Most cats were caught with rabbit as bait, and visual and olfactory lures added to baits did not appear to increase capture efficiency, although the power of the test was limited. Most captured cats were adult males weighing 4.37 0.14 kg; these were larger than the females (3.34 0.06 kg). Litters, comprising 2–5 kittens, were born between September and March.
A total of 76 feral cats (Felis catus) (29 individuals; 47 recaptures) was trapped during 6027 trap-nights using both cage and leg-hold traps from November 1994 to August 1996 at Lake Burrendong in central New South Wales. No significant difference was found in the relative capture efficiency between cage and leg-hold traps (P > 0.05). Overall capture efficiency was 1.3 cats per 100 trap-nights, although this varied seasonally, being higher in late autumn and early winter. Most cats were caught with rabbit as bait, and visual and olfactory lures added to baits did not appear to increase capture efficiency, although the power of the test was limited. Most captured cats were adult males weighing 4.37 0.14 kg; these were larger than the females (3.34 0.06 kg). Litters, comprising 2–5 kittens, were born between September and March.
Wednesday, 5 June 2013
Domestic cat gene introgression into wild cat in Europe
Randi, E., Pierpaoli, M., Beaumont, M., Ragni, B., & Sforzi, A. (2001). Genetic identification of wild and domestic cats (Felis silvestris) and their hybrids using Bayesian clustering methods. Molecular Biology and Evolution, 18(9), 1679-1693.
Crossbreeding with free-ranging domestic cats is supposed to threaten the genetic integrity of wildcat populations in Europe, although the diagnostic markers to identify "pure" or "admixed" wildcats have never been clearly defined. Here we use mitochondrial (mt) DNA sequences and allelic variation at 12 microsatellite loci to genotype 128 wild and domestic cats sampled in Italy which were preclassified into three separate groups: European wildcats (Felis silvestris silvestris), Sardinian wildcats (Felis silvestris libyca), and domestic cats (Felis silvestris catus), according to their coat color patterns, collection localities, and other phenotypical traits, independently of any genetic information. For comparison, we included some captive-reared hybrids of European wild and domestic cats. Genetic variability was significantly partitioned among the three groups (mtDNA estimate of F(ST) = 0.36; microsatellite estimate of R(ST) = 0.30; P < 0.001), suggesting that morphological diversity reflects the existence of distinct gene pools. Multivariate ordination of individual genotypes and clustering of interindividual genetic distances also showed evidence of distinct cat groups, partially congruent with the morphological classification. Cluster analysis, however, did not enable hybrid cats to be identified from genetic information alone, nor were all individuals assigned to their populations. In contrast, a Bayesian admixture analysis simultaneously assigned the European wildcats, the Sardinian wildcats, and the domestic cats to different clusters, independent of any prior information, and pointed out the admixed gene composition of the hybrids, which were assigned to more than one cluster. Only one putative Sardinian wildcat was assigned to the domestic cat cluster, and one presumed European wildcat showed mixed (hybrid) ancestry in the domestic cat gene pool. Mitochondrial DNA sequences indicated that three additional presumed European wildcats might have hybrid ancestry. These four cats were sampled from the same area in the northernmost edge of the European wildcat distribution in the Italian Apennines. Admixture analyses suggest that wild and domestic cats in Italy are distinct, reproductively isolated gene pools and that introgression of domestic alleles into the wild-living population is very limited and geographically localized.
Pierpaoli, M., Birò, Z.S., Herrmann, M., Hupe, K., Fernandes, M., Ragni, B., Szemethy, L. & Randi, E. (2003). Genetic distinction of wildcat (Felis silvestris) populations in Europe, and hybridization with domestic cats in Hungary. Molecular Ecology 12: 2585-2598.
The genetic integrity and evolutionary persistence of declining wildcat populations are threatened by crossbreeding with widespread free-living domestic cats. Here we use allelic variation at 12 microsatellite loci to describe genetic variation in 336 cats sampled from nine European countries. Cats were identified as European wildcats (Felis silvestris silvestris), Sardinian wildcats (F. s. libyca) and domestic cats (F. s. catus), according to phenotypic traits, geographical locations and independently of any genetic information. Genetic variability was significantly partitioned among taxonomic groups (FST = 0.11; RST = 0.41; P < 0.001) and sampling locations (FST = 0.07; RST = 0.06; P < 0.001), suggesting that wild and domestic cats are subdivided into distinct gene pools in Europe. Multivariate and Bayesian clustering of individual genotypes also showed evidence of distinct cat groups, congruent with current taxonomy, and suggesting geographical population structuring. Admixture analyses identified cryptic hybrids among wildcats in Portugal, Italy and Bulgaria, and evidenced instances of extensive hybridization between wild and domestic cats sampled in Hungary. Cats in Hungary include a composite assemblage of variable phenotypes and genotypes, which, as previously documented in Scotland, might originate from long lasting hybridization and introgression. A number of historical, demographic and ecological conditions can lead to extensive crossbreeding between wild and domestic cats, thus threatening the genetic integrity of wildcat populations in Europe.
Lecis, R., Pierpaoli, M., Biro, Z. S., Szemethy, L., Ragni, B., Vercillo, F., & Randi, E. (2006). Bayesian analyses of admixture in wild and domestic cats (Felis silvestris) using linked microsatellite loci. Molecular Ecology, 15(1), 119-131.
Methods recently developed to infer population structure and admixture mostly use individual genotypes described by unlinked neutral markers. However, Hardy–Weinberg and linkage disequilibria among independent markers decline rapidly with admixture time, and the admixture signals could be lost in a few generations. In this study, we aimed to describe genetic admixture in 182 European wild and domestic cats (Felis silvestris), which hybridize sporadically in Italy and extensively in Hungary. Cats were genotyped at 27 microsatellites, including 21 linked loci mapping on five distinct feline linkage groups. Genotypes were analysed with structure 2.1, a Bayesian procedure designed to model admixture linkage disequilibrium, which promises to assess efficiently older admixture events using tightly linked markers. Results showed that domestic and wild cats sampled in Italy were split into two distinct clusters with average proportions of membership Q > 0.90, congruent with prior morphological identifications. In contrast, free-living cats sampled in Hungary were assigned partly to the domestic and the wild cat clusters, with Q < 0.50. Admixture analyses of individual genotypes identified, respectively, 5/61 (8%), and 16–20/65 (25–31%) hybrids among the Italian wildcats and Hungarian free-living cats. Similar results were obtained in the past using unlinked loci, although the new linked markers identified additional admixed wildcats in Italy. Linkage analyses confirm that hybridization is limited in Italian, but widespread in Hungarian wildcats, a population that is threatened by cross-breeding with free-ranging domestic cats. The total panel of 27 loci performed better than the linked loci alone in the identification of domestic and known hybrid cats, suggesting that a large number of linked plus unlinked markers can improve the results of admixture analyses. Inferred recombination events led to identify the population of origin of chromosomal segments, suggesting that admixture mapping experiments can be designed also in wild populations.
See more on domestic cat gene introgression in wildcat
Pierpaoli, M., Birò, Z.S., Herrmann, M., Hupe, K., Fernandes, M., Ragni, B., Szemethy, L. & Randi, E. (2003). Genetic distinction of wildcat (Felis silvestris) populations in Europe, and hybridization with domestic cats in Hungary. Molecular Ecology 12: 2585-2598.
Lecis, R., Pierpaoli, M., Biro, Z. S., Szemethy, L., Ragni, B., Vercillo, F., & Randi, E. (2006). Bayesian analyses of admixture in wild and domestic cats (Felis silvestris) using linked microsatellite loci. Molecular Ecology, 15(1), 119-131.
See more on domestic cat gene introgression in wildcat
Saturday, 4 May 2013
Conservation of Zino petrel
Zino F. et al. (2001) Conservation of Zino's petrel Pterodroma madeira in the archipelago of Madeira. Oryx, 35, 128-136.
Birds restricted to islands are susceptible to extinction, and burrow or ground-nesting birds are particularly vulnerable to introduced mammalian predators. Human intervention has also played a vital part. Birds have been used as a source of food, and in more recent times the rarer species have suffered from specimen and egg collection. The island of Madeira and its resident species, which include the endemic Zino's petrel or Madeira freira Pterodroma madeira, are no exception. From subfossil evidence, this bird was once abundant. It was first recorded in 1903, and was already limited to the high central mountain massif of Madeira. By the middle of the century it was considered extinct, but a relict population was rediscovered in 1969. By 1985, all known breeding attempts were disrupted by introduced rats, to the extent that no young fledged. In 1986 the Freira Conservation Project was founded with the aim of increasing the population of Zino's petrel, by controlling rats and human interference, the principal perceived threats to the species. This control was extended to cats after the disaster of 1991, in which a cat(s) managed to get onto one of the breeding ledges and kill 10 adult birds. The results of these efforts have been positive and the small colony is making a slow, but steady recovery. To maintain this success, a conservation strategy for the future is suggested.
Birds restricted to islands are susceptible to extinction, and burrow or ground-nesting birds are particularly vulnerable to introduced mammalian predators. Human intervention has also played a vital part. Birds have been used as a source of food, and in more recent times the rarer species have suffered from specimen and egg collection. The island of Madeira and its resident species, which include the endemic Zino's petrel or Madeira freira Pterodroma madeira, are no exception. From subfossil evidence, this bird was once abundant. It was first recorded in 1903, and was already limited to the high central mountain massif of Madeira. By the middle of the century it was considered extinct, but a relict population was rediscovered in 1969. By 1985, all known breeding attempts were disrupted by introduced rats, to the extent that no young fledged. In 1986 the Freira Conservation Project was founded with the aim of increasing the population of Zino's petrel, by controlling rats and human interference, the principal perceived threats to the species. This control was extended to cats after the disaster of 1991, in which a cat(s) managed to get onto one of the breeding ledges and kill 10 adult birds. The results of these efforts have been positive and the small colony is making a slow, but steady recovery. To maintain this success, a conservation strategy for the future is suggested.
Monday, 7 January 2013
Wildlife response to dogs
Miller, S.G., Knight, R.L. & Miller, C.K. 2001. Wildlife responses to pedestrians and dogs. Wildlife Society Bulletin, 29 (1): 124-132.
You can download here the homonimous report from 1996
As participation in outdoor recreational activities escalates, land managers struggle to develop management policies that ensure coexistence of wildlife and recreation. However, this requires an understanding of how wildlife responds to various forms of recreational activities and the spatial context in which the activities occur. Therefore, we measured responses of 2 species of grassland songbirds, one species of forest songbird, and mule deer (Odocoileus hemionus) exposed to a pedestrian, a pedestrian accompanied by a dog on leash, and a dog alone (only for grassland birds), on and away from recreational trails. We assessed the "area of influence" for each treatment by determining the probability that an animal would flush or become alert (for mule deer only) given its perpendicular distance to a trail or a line of movement in areas without trails. When animals were disturbed, we measured flush distance (the distance between the disturbance and the animal when flushed), distance moved, and, for mule deer, alert distance (the distance between the disturbance and the deer when it became alert). For all species, area of influence, flush distance, distance moved, and alert distance (for mule deer) was greater when activities occurred off-trail versus on-trail. Generally, among on-trail and off-trail treatments in grasslands for vesper sparrows (Pooecetes gramineus) and western meadowlarks (Sturnella neglecta), the smallest area of influence and shortest flush distance and distance moved resulted from the dog-alone treatment, and these responses were greater for the pedestrian-alone and dog-on-leash treatments. In forests, for American robins (Turdus migratorius), the area of influence, flush distance, and distance moved did not generally differ between the pedestrian-alone and dog-on-leash treatments. For mule deer, presence of a dog resulted in a greater area of influence, alert and flush distance, and distance moved than when a pedestrian was alone. Natural lands managers can implement spatial and behavioral restrictions in visitor management to reduce disturbance by recreational activities on wildlife. Restrictions on types of activities allowed in some areas such as prohibiting dogs or restricting use to trails will aid in minimizing disturbance. Additionally, managers can restrict the number and spatial arrangement of trails so that sensitive areas or habitats are avoided.
You can download here the homonimous report from 1996
As participation in outdoor recreational activities escalates, land managers struggle to develop management policies that ensure coexistence of wildlife and recreation. However, this requires an understanding of how wildlife responds to various forms of recreational activities and the spatial context in which the activities occur. Therefore, we measured responses of 2 species of grassland songbirds, one species of forest songbird, and mule deer (Odocoileus hemionus) exposed to a pedestrian, a pedestrian accompanied by a dog on leash, and a dog alone (only for grassland birds), on and away from recreational trails. We assessed the "area of influence" for each treatment by determining the probability that an animal would flush or become alert (for mule deer only) given its perpendicular distance to a trail or a line of movement in areas without trails. When animals were disturbed, we measured flush distance (the distance between the disturbance and the animal when flushed), distance moved, and, for mule deer, alert distance (the distance between the disturbance and the deer when it became alert). For all species, area of influence, flush distance, distance moved, and alert distance (for mule deer) was greater when activities occurred off-trail versus on-trail. Generally, among on-trail and off-trail treatments in grasslands for vesper sparrows (Pooecetes gramineus) and western meadowlarks (Sturnella neglecta), the smallest area of influence and shortest flush distance and distance moved resulted from the dog-alone treatment, and these responses were greater for the pedestrian-alone and dog-on-leash treatments. In forests, for American robins (Turdus migratorius), the area of influence, flush distance, and distance moved did not generally differ between the pedestrian-alone and dog-on-leash treatments. For mule deer, presence of a dog resulted in a greater area of influence, alert and flush distance, and distance moved than when a pedestrian was alone. Natural lands managers can implement spatial and behavioral restrictions in visitor management to reduce disturbance by recreational activities on wildlife. Restrictions on types of activities allowed in some areas such as prohibiting dogs or restricting use to trails will aid in minimizing disturbance. Additionally, managers can restrict the number and spatial arrangement of trails so that sensitive areas or habitats are avoided.
Sunday, 6 January 2013
Predation on NZ shorebirds
Dowding, J. E., & Murphy, E. C. (2001). The impact of predation by introduced mammals on endemic shorebirds in New Zealand: a conservation perspective.Biological Conservation, 99(1), 47-64.
The avifauna of New Zealand has been severely depleted since human colonisation and currently contains a disproportionately high number of threatened species. Of the 23 threatened shorebird species worldwide, six are endemic to New Zealand. We review the status of New Zealand's endemic shorebirds and examine the impact on them of various threats, particularly predation by introduced mammals. The conservation status of the 10 extant species (three oystercatchers, one stilt, four plovers and two snipe) is outlined and the factors that predisposed them to predation by introduced mammals are summarised. Individual species accounts are presented, including data on population trends, known or suspected impacts of predation, identification of important predator species, other threats, and conservation measures currently in place or required. One species and two subspecies are extinct, three species are confined to predator-free islands and another is found only on the Chatham Islands group. Six survive on the mainland but three have declined to varying degrees and are assigned threatened status by Collar et al. (1994). Only one plover and two oystercatchers are still relatively numerous and/or widespread. Rats, cats and mustelids have had the greatest overall impacts. Conservation measures in place to mitigate the effects of introduced predators include the formulation of recovery plans, predator control around breeding areas, captive breeding and rearing programmes and the founding of new populations by translocation. There are often substantial differences in susceptibility to predation of closely related or ecologically similar taxa, and we stress the importance of basing conservation management decisions on relevant and detailed demographic and ecological studies. The main threat to threatened shorebirds elsewhere in the world is loss or degradation of habitat; the disproportionate impact of mammalian predators on New Zealand shorebirds is unusual but not unique.
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