Habitat and mesopredator activity as predictors of bird densitiy in urban parks

Thieme, J. L., Rodewald, A. D., Brown, J., Anchor, C., & Gehrt, S. D. (2015). Linking Grassland and Early Successional Bird Territory Density to Predator Activity in Urban Parks. Natural Areas Journal, 35(4), 515-532.

The proximity of urban green spaces to anthropogenic food sources can promote high densities of predators that may negatively affect breeding birds. Not only can high numbers of predators depress reproduction and survival, but birds may behaviorally respond by avoiding those patches, thereby diminishing the value of urban habitats. During 2010 and 2011, we examined relationships between avian territory density and activity of nest predators in 36 2-ha plots within six urban grassland and early successional parks (sites) near Chicago, Illinois. At the plot (i.e., local) scale, densities of common yellowthroats (Geothlypis trichas), field sparrows (Spizella pusilla), and savannah sparrows (Passerculus sandwichensis) were more strongly linked to habitat characteristics than predators. Song sparrow (Melospiza melodia) and eastern meadowlark (Sturnella magna) densities were not associated with habitat at the plot scale, but together were negatively related to activity of avian predators. Surprisingly, densities of song sparrows were positively associated with snake activity at both plot and site (i.e., landscape) scales, and densities of savannah sparrows increased moderately with activity of mesopredators at the site scale. Our results suggest that although habitat structure is a strong predictor of grassland bird densities in this urban matrix, activity of predators also may contribute to patterns of territory selection of certain bird species. With this in mind, managers encouraging settlement of grassland birds within urban preserves may consider (a) increasing dense groundcover that provides protective cover for songbirds, and (b) discouraging activities that promote activity of avian predators, particularly corvids.

Review of domestic dogs in parks

Weston, M. A., Fitzsimons, J. A., Wescott, G., Miller, K. K., Ekanayake, K. B., & Schneider, T. (2014). Bark in the Park: A Review of Domestic Dogs in Parks. Environmental Management, 1-10.


The presence of domestic dogs Canis familiaris in public open spaces is increasingly controversial. In our review of the literature, we located 133 publications of various types (papers, reports etc.) that examine some aspect of dogs in parks and open spaces (50 % focussed solely on dogs). There has been an exponential growth in the cumulative number of articles (R 2 = 0.96; 82 % published since 1997); almost all pertain to temperate latitudes (97 %) and most to the northern hemisphere (62 %). Most articles focus on impacts on wildlife (51 %), zoonotic diseases (17 %), and people’s perceptions regarding dogs (12 %). Articles mostly describe problems associated with dogs, while reports of low compliance with dog regulations are common. We outline six major findings regarding dogs in parks: (1) there is a paucity of information on dogs in parks, particularly in relation to their interactions with wildlife and regarding their management; (2) published studies are mainly restricted to a handful of locations in developed countries; (3) sectors of societies hold different views over the desirability of dogs in parks; (4) the benefits and risks of dogs to humans and park values are poorly documented and known; (5) dogs represent a notable disease risk in some but not all countries; and (6) coastal parks are over-represented in the literature in terms of potential negative impacts. Park managers globally require better information to achieve conservation outcomes from dog management in parks.

Feeding cats deplates native fauna

Hawkins, C.C., W.E. Grant & M.T. Longnecker. 1999. Effect of subsidized house cats on California birds and rodents. Transactions of the Western Section of The Wildlife Society, 35: 29-33

Cat advocates are establishing feeding stations in public parks, often claiming that well-fed cats pose little threat to wildlife. This claim was tested east of San Francisco, California, in a cat area and a no-cat area. In 1995, more harvest mice were trapped in the no-cat area. In 1996, more harvest mice (Reithrodontomys megalotis) and deer mice (Peromyscus sp.) were trapped in the no-cat area, and more house mice were trapped in the cat area. The numbers of trapped California meadow voles (Microtus californicus) were not different between the areas in either year. More native rodents were trapped in the no-cat area. Birds present during the breeding season were seen more often in the no-cat area. California quail (Callipepla californicus) and California thrashers (Toxostoma redivivum) were present in the no-cat area and absent in the cat area. Cats at artificially high densities, sustained by supplementary feeding, reduced the abundance or native rodent and bird populations, changed the rodent species composition, and may have facilitated the expansion of the house mouse into new areas. Thus we recommend that the feeding of cats in parks should be strictly prohibited. 

The effect of design, and dogs, on bird species on urban parks

Paker, Y., Yom-Tov, Y., Alon-Mozes, T., & Barnea, A. (2013). The effect of plant richness and urban garden structure on bird species richness, diversity and community structure. Landscape and Urban Planning.

Urban green areas improve the standard of living in cities and affect people's attitude to nature and conservation. Zoological knowledge may provide data that will help designers to enhance bird diversity in gardens. We studied the effect of plant species richness and structure on bird species richness, diversity and community structure in 25 public gardens in Tel-Aviv city and, neighboring suburbs, Israel. A total of 65 bird species were observed, of which nine were urban, exploiters or alien species. These latter species composed 54% of all individuals seen. Additional 13 bird species, mostly migrants, were observed in gardens further from the observation fixed radius. We found that shrubs species richness positively affected bird species diversity. Most bird species were found where trees and shrubs species richness was high, and trees and lawn cover were medium or low. High trees or high lawn cover attracted only a few bird species, mostly aliens and urban exploiters. Native birds preferred to forage on native trees and alien birds preferred to feed on alien trees. Bird species diversity was higher during spring and fall because of the presence of migrating bird species. Dogs and people had a negative effect on bird presence. Accordingly, we recommend that when planning new gardens, designers will avoid large lawns, prefer diverse and dense shrubberies, native trees, and will create some areas that will not be accessible to dogs and people. Finally, we emphasize the importance of multidisciplinary studies conducted in collaboration between landscape designers and zoologists.

Cats' spatial interference with coyotes

Gehrt SD, Wilson EC, Brown JL, Anchor C (2013) Population Ecology of Free-Roaming Cats and Interference Competition by Coyotes in Urban Parks. PLoS ONE 8(9)

Free-roaming cats are a common element of urban landscapes worldwide, often causing controversy regarding their impacts on ecological systems and public health. We monitored cats within natural habitat fragments in the Chicago metropolitan area to characterize population demographics, disease prevalence, movement patterns and habitat selection, in addition to assessing the possible influence of coyotes on cats. The population was dominated by adults of both sexes, and 24% of adults were in reproductive condition. Annual survival rate was relatively high (S=0.70, SE=0.10), with vehicles and predation the primary causes of death. Size of annual home range varied by sex, but not reproductive status or body weight. We observed partitioning of the landscape by cats and coyotes, with little interspecific overlap between core areas of activity. Coyotes selected for natural habitats whereas cats selected for developed areas such as residences. Free-roaming cats were in better condition than we predicted, but their use of natural habitat fragments, and presumably their ecological impact, appeared to be limited by coyotes through intraguild competition.

Antipredator strategies of house finches in towns

Valcarcel, A., & Fernández-Juricic, E. (2009). Antipredator strategies of house finches: are urban habitats safe spots from predators even when humans are around?. Behavioral Ecology and Sociobiology, 63(5), 673-685.

Urbanization decreases species diversity, but it increases the abundance of certain species with high tolerance to human activities. The safe-habitat hypothesis explains this pattern through a decrease in the abundance of native predators, which reduces predation risk in urban habitats. However, this hypothesis does not consider the potential negative effects of human-associated disturbance (e.g., pedestrians, dogs, cats). Our goal was to assess the degree of perceived predation risk in house finches (Carpodacus mexicanus) through field studies and semi-natural experiments in areas with different levels of urbanization using multiple indicators of risk (flock size, flight initiation distance, vigilance, and foraging behavior). Field studies showed that house finches in more urbanized habitats had a greater tendency to flock with an increase in population density and flushed at larger distances than in less urbanized habitats. In the semi-natural experiment, we found that individuals spent a greater proportion of time in the refuge patch and increased the instantaneous pecking rate in the more urbanized habitat with pedestrians probably to compensate for the lower amount of foraging time. Vigilance parameters were influenced in different ways depending on habitat type and distance to flock mates. Our results suggest that house finches may perceive highly urbanized habitats as more dangerous, despite the lower number of native predators. This could be due to the presence of human activities, which could increase risk or modify the ability to detect predators. House finches seem to adapt to the urban environment through different behavioral strategies that minimize risk.

Subsidies influence on feral cat distribution and abundance

Tennent, J. & C.T. Downs. 2008. Abundance and home ranges of feral cats in an urban conservancy where there is supplemental feeding: a case study from South Africa. African Zoology 43(2):218-229.


There is much debate surrounding the impact of feral cats (Felis catus) on wildlife. Conservancies are usually areas where indigenous flora and fauna are protected and aliens excluded or managed. The University of KwaZulu-Natal's Howard College campus (HCC) is an urban conservancy containing feral cats that are presently not managed, and little is known about their ecology and behaviour. Consequently a feral cat population census was conducted, and their home range investigated. Estimates of the overall campus feral cat population numbers ranged between 23.4–40.0 cats/km² with a minimum of 55 identified as resident. They were not randomly distributed in the study area, with spacing patterns being related to resource availability. Home range area and core distribution of eight radio-collared cats were determined over 13 months. Total home range areas were relatively small, with considerable overlap between them. Home ranges were clustered in areas with permanent feeding stations and these were also within the cats' core ranges. Supplemental food resources appear to have a major influence on numbers, home and core range area, and behavior of cats. It is clear that cat densities grow to high levels with reliable and abundant food supply and only ad hoc sterilization. This has implications for their management in the HCC urban conservancy.

Leash regulations lack of impact on small vertebrates

Forrest, A. & C.C. St. Clair. 2006. Effects of dog leash laws and habitat type on avian and small mammal communities in urban parks. Urban Ecosystems, 9:51–66

Remnant natural areas within urban settings can act as important refuges for wildlife, substantially increasing local biodiversity. However, habitat suitability for these species is potentially affected by human recreational activities including the presence of free-running dogs. To compare the diversity and abundance of songbird and small mammal communities between areas with bylaws that require, or do not require, dogs to be leashed, point counts and live-trapping surveys were conducted in three habitat types (deciduous, coniferous, and meadow) in the river valley parks of Edmonton, Alberta. Among birds, there was no difference between areas with different leashing bylaws in species diversity for any of the three habitat types. Similarly, there was no difference in bird diversity for a subset of species that were plausibly breeding at these sites. However, higher bird diversity was recorded in deciduous and coniferous sites than in meadow sites, regardless of leash designation, probably as a function of the horticultural practice of mowing meadows. Among both birds and small mammals, there was no difference in the abundance of individuals as a function of leashing bylaws. Our results suggest that off-leash dogs have no effect on the diversity or abundance of birds and small mammals in urban parks, but it is also possible that other factors, such as leash law compliance, reduced or obscured the effects of off-leash dogs in this study.

Other perspective on the impact of urban cats

Although the summary don't come into detail, the author states that feral cats have positive effects: predation on rodents, anti-depressive effect for cat-carers, educative impact for children and adults and aesthetic effects. On the negative side, just hygiene and public health.

Natoli, E. 1994. Urban feral cats (Felis catus L.): perspectives for a demographic control respecting the psycho-biologicalwelfare of the species. Ann. Ist. Super. Sanità, 30 (2): 223-227

The presence of feral cats in the urban environment is creating problems of acceptance by human beings, especially in relation to health aspects. In accordance with the protectionist spirit of the law 281 of 14/8/91, the new sensitivity of the Public Veterinary Services for feral cat control in the cities are proposed. These consist mainly in demographic control by means of neutering the cats, with particular attention to the psycho-biological welfare of the species.