on twitter ...

Most people who keep cats deny or refuse to accept the wildlife damage caused by their pet(s). http://t.co/i0G4kqzt3K pic.twitter.com/IuTPrx3upt
— Nick P. Williams (@TheFalconBirder) Mayo 12, 2014

Urban cat ownership in Baltimore

Childs, J. E. (1990). Urban cats: their demography, population density, and owner characteristics in Baltimore, Maryland. Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 3(4), 234-244.

A door-to-door questionnaire survey of 430 households in two areas of Baltimore showed significant differences in cat ownership that were attributable to racial composition. Overall, 29.9% of white households owned a mean of 1.9 cats per cat-owning household, compared to 6.8% of black households owning a mean of 1.0 cat per cat-owning household. The mean age of cats was 3.9 yrs and 1.8 yrs in white and black households, respectively. In contrast, dog ownership in the two areas was nearly identical, with 25.6% of white and 29.1% of black households owning a mean of 1.5 and 1.3 dogs per dog-owning household, respectively. Overall, 62.8% of owned cats were spayed/neutered, 51.8% had received a vaccination in the last year, and 34.7% had been wormed during their lifetimes. A total of 31.6% of households allowed their cats to free-range; 42.5% of the 87 owned cats were in this category. The estimated densities of owned free-ranging cats were 7.0 and 2.8 cats per hectare, for the two areas. Driving counts of free-ranging animals in the two areas suggested a larger population of stray or feral cats in the location with lower reported cat ownership.

Humans and stray cats in NY

Haspel, C., & Calhoon, R. E. (1990). The interdependence of humans and free-ranging cats in Brooklyn, New York. Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 3(3), 155-161.

Based on the responses of 177 participants in a survey conducted in Brooklyn, New York, it was ascertained that 22.0% of the respondents fed free-ranging cats (2.8% daily and 19.2% occasionally). The food provided by feeders alone was estimated to support 1.71 to 2.10 cats per acre (4.2 to 5.2 cats per hectare), a density that is 1.35 times greater than the actual cat population. Other resources provided (e.g., shelter, medical help, adoption) were also estimated. Daily feeders were devoted to their cats. They continued to feed them despite the disapproval of their neighbors, financial constraints, or social obligations. Free-ranging cats appear to be in a mutually life-enhancing relationship with their feeders.

Diet of feral cats on farmland in New Zealand

Langham, N. P. E. (1990). The diet of feral cats (Felis catus L.) on Hawke’s Bay farmland, New Zealand. New Zealand journal of zoology, 17(2), 243-255.

Food remains were analysed in 361 cat faeces (scats) collected from September 1983 to May 1987 on farmland in southern Hawke’s Bay. Mammals were the most important food items in scats, both by occurrence (76%) and by weight (74%). House mice were the most frequently (50%) encountered remains, and comprised only 12% of the total prey identified by weight; rats were less frequently found (20%) but the most important item by weight (39%). Other mammals found were scavenged possums (13% by weight), sheep (7%), and lagomorphs (3%). Birds, consisting mainly of introduced species, including turkeys, were both frequent (24%) and important by weight (24%). Invertebrate remains consisted mainly of cicada nymphs (Homoptera) (10% by frequency), grass grubs (Coleoptera) (8%), and black field crickets (Orthoptera) (7%) contributed less than 2% by weight. Cicada nymphs were recorded only in willow/ swamp habitat. No significant differences were found between vertebrate prey recorded in scats from willows and swamps and vertebrate prey from bams and pasture. There were no consistent local or seasonal changes in frequency of occurrence of rats, but mice were found more frequently in scats collected in winter. Possum remains were found mainly in winter. Birds were the main items in scats collected in the spring and summer months. Eggs of Toxocari cati (64%) were the only identifiable internal parasite frequently found in the scats.

Roaming, stray, and feral domestic cats and dogs as wildlife problems

Van't Woudt, B. D. (1990). Roaming, stray, and feral domestic cats and dogs as wildlife problems. Proceedings of the Fourteenth Vertebrate Pest Conference 1990, Sacramento, California

From several centers of domestication, cats and dogs have become the near-ubiquitous companion of man. Their dependence on man is such that when abandoned in a rural environment most succumb to malnutrition in combination with predation, diseases, parasites, and exposure. Where not subject to predation and where native or introduced prey is adequate, some survive to form feral populations. This applies on oceanic islands, in Australia and New Zealand. Elsewhere, as far as is known today, requirements for survival are met with in parts of the U.S. and Europe only, in remote wilderness areas in the case of dogs, and more widespread, with a tendency to fall back on surplus and waste products of man during hard times in the wild, in the case of cats. Where vermin populations, such as those of rabbits, rats and mice are dense, cats provide inadequate control; they can be useful in keeping small vermin populations small. Away from oceanic islands and desert areas, where their impact on native animals can be disastrous, this makes them sufficiently useful for damage to wildlife (notably to lizards, small marsupials and some birds) to be outweighed, without providing a clear-cut case for a need for control of either roaming, stray or feral cats in rural areas. On the other hand, dogs are potentially destructive animals, whether roaming, stray, or feral; they demand strict control

Feral cat eradication on a barrier reef island

Domm, S. & Messersmith, J. 1990. Feral cat eradication on a barrier reef island, Australia. Atoll Research Bulletin, 338, 1-4.

Shooting during the day was found to be most effective. Eight cats were trapped, 95 shot (16 at night) and 2 corpses were found after baiting with 1080.

Cat diet in Macaronesia (Atlantic Ocean)

More than a dozen of papers describing the diet of feral cats on most of Macaronesian islands (Cape Verde, Canary Island and Madeira), Atlantic Ocean.
Although exotic mammals represent an important proportion of their  diet, native species suffer a strong impact from cat's predation.

Macaronesia

1 Medina F. M., Oliveira P., Menezes D., Teixeira S., García R. & Nogales M. 2010. Trophic habits of feral cats in the high mountain shrublands of the Macaronesian islands (NW Africa, Atlantic Ocean). Acta Theriologica 55: 241–250.
Feral cats Felis catus Linnaeus, 1758 have contributed to the extinction of numerous native species on islands, which are clearly sources of global biodiversity. We studied the diet of this introduced predator in the Madeira and Cape Verde archipelagos, which harbour important colonies of endangered sea birds in the high mountain habitats, and compared the results with those obtained in the same habitat in the Canary Islands, Macaronesian archipelago. On Madeira, 461 prey were iden ti fied from 143 scat groups. Mammals, over all mice, constituted the basic diet appearing in 95% of cat scats. On Fogo (Cape Verde), 657 prey items were obtained from 145 scats, and mammals were also the most important prey, reaching a frequency of occurrence of 88%. Although introduced mammals were the main prey category on all Macaronesian islands, we observed variation in feral cat diet among these is lands. Birds were more frequently consumed on Madeira, lizards on Tenerife (Canaries) and invertebrates on Fogo. No specific differences were observed in relation to La Palma.We suggest that the diet composition on these islands varies according to the respective availability of the different prey types.

Canary Islands

2 Nogales, M., A. Martín, G. Delgado & K. Emmerson. 1988. Food spectrum of the feral cat (Felis catus L., 1758) in the juniper woodland on El Hierro (Canary Islands). Bonner Zoologische Beiträge 39: 1-6.
The diet of feral cats inhabiting a juniper woodland on the island of El Hierro (Canary Islands) has been studied by analyzing 248 scats. A total of 1029 prey items have been identified indicating that the introduced mammals (Oryctolagus cuniculus, Mus sp. and Rattus sp.) constitute the basis of the diet appearing in 88.3 % of the samples and representing 85.4 % of the consumed biomass. Mus sp. is the most frequently captured prey but in terms of biomass. Mus sp. is the most frequently captured prey but in terms of biomass, Oryctolagus cuniculus is the fundamental bais of the diet as has similarly been found in other areas studied. Birds can be regarded as alternative prey resources of some importance though they only account for 8 % of the biomass with Cory's shearwater (Calonectris diomedea), contributing practically half this value. Reptiles appear in 44.3 % of the scats but only represent 5.9 % of the biomass, Gallotia galloti caesaris being the most frequently captured species (64.1 %). Insects, (mainly Orthoptera & Coleoptera), despite their high frequency of apparition (45.5 % of scat groups), are insignificant due to their small size, though worthy of note is the large number of larvas of Pimelia laevigata.

3 Nogales, M., M. Abdola, C. Alonso & V. Quilis. 1990. Premiêres données sur l’alimentation du chat haret (Felis catus L., 1758) du Parc National du Teide. Ténérife (Iles Canaries) Mammalia, 54: 189-196. 

Le régime alimentaire du chat haret (Felis catus) est étudié à partir de 221 groupes d'excréments (environ 600 excréments) collectés dans le Parc National du Teide (Ténérife), apportant ainsi des données sur les proies capturées, leur fréquence d'apparition dans les groupes d'excréments et leur biomase. De l'étude de ce matériel on dégage que le régime se compose surtout d'Oryctolagus cuniculus, qui représente une biomasse de 64,4% et une fréquence d'apparition de 53,8%, et de reptiles (Principalement de Gallotia galloti, lézard endémiques des iles Canaries occidentales) avec 74,2%, une fréquence d'apparition en groupes de 74,2% et une biomasse de 20,6%.

In this paper we present preliminary data concerning the food spectrum on the feral cat in the Teide National Park on Tenerife. After having analysed 221 scats, 523 prey items have been identified. Rabbits (Oryctolagus cuniculus) are the fundamental base of the diet (frecuency of apparition 53,8% and biomass 65,4%) as has been similarly found in other areas studied. Also, reptiles (principally Gallotia galloti, an endemic lizard on the Western Canary Islands) was frequently captured, appearing in 74,2% of the scats groups and representing 20,6% of the total biomass.

4 Nogales, M., J.L. Rodríguez, G. Delgado, V. Quilis & O. Trujillo. 1992. The diet of feral cats (Felis catus) on Alegranza Island (North of Lanzarote, Canary Islands). Folia Zoologica 4: 209-212.
The diet of feral cats on Alegranza has been studied by analyzing 110 scats. A total of 199 prey items have been identified indicating that introduced mammals (Oryctolagus cuniculus and Mus sp.) constitute the basis of the diet appearing in 100 of the samples and representing 99,5% of the consumed biomass, Fortunately, it appears that breeding seabirds are not represented in their diet. However the species constitutes a potential threat to the birds if its present prey declines in number.

5 Nogales, M. & F.M. Medina. 1996. A review of the diet of feral domestic cats (Felis silvestris f. catus) on the Canary Islands, with new data from the laurel forest of La Gomera. Zeitschrift für Säugetierkunde 61: 1-6. 

In this study we present a review on the diet of the feral cat on the Canary archipelago, providing the first data from the reliet laurel forest (Garajonay National Park). Among the 403 prey items identified in this habitat, rats were most numerous followed by reptiles. A total of 1.047 scat groups has been studied in the lat eight years from the main habitats of the Canaries. Most of the 2.963 prey items identified represent introduced mammals (rabbit, Oryctolagus cuniculus; mouse, Muscf. musculus and rat, Rattus sp.). These prey were commonly captured in most habitats with the exception of high mountain scrub. In this habitat, reptiles were taken instead introduced mammals. They were also more commonly included in the diet from open ground and open forest than from the denser forest. Birds were more frecuently consumed in the forest than in open areas. Anthropods appeared in significant proportions in the scats from habitats where these items reached high numbers. The results indicate that the diet of feral cats clearly varies according to the different habitats.

6 Medina, F.M., R. García & M. Nogales, 2006. Feeding ecology of feral cats on a heterogeneous subtropical oceanic island (La Palma, Canarian Archipelago). Acta Theriologica 51: 75−83.
We found a total of 987 prey in the 500 scats of feral cats Felis silvestris catus Linnaeus, 1758 analyzed in the present study. Introduced mammals (rabbits, rats and mice) constituted the most important prey both in percentage and biomass. Reptiles were the second most important prey, being more frequent than birds and inver te brates. Mammals were the most frequently eaten group in all five main habitats of the island, being more frequent than the remainder of prey in the laurel forest. Rabbits appeared more often in the temperate forest, rats in the laurel forest and mice in the high mountain. Birds were more frequently captured in the three higher habitats (laurel and pine forest, and high mountain) than in the two lower ones (xerophytic shrub and temperate forest). Reptiles were preyed on less in the laurel forest than in the other main habitats. Morisita index indicates a high trophic overlap among the different habitats with the exception of the laurel forest which shows important differences from the other habitats. Levin’s niche-breadth was broader in the xerophytic shrub and narrower in the temperate forest, reaching in ter mediate levels in the other three main habitats. The results obtained in the present study evidence a general pattern in the trophic ecology among similar habitats in the different subtropical Canarian islands. However, some important differences exist that could be a function of the differential prey availability and composition in each ecosys tem.

7 Medina, F.M. & R. García. 2007. Predation of insects by feral cats (Felis silvestris catus L., 1758) on an oceanic island (La Palma, Canary Islands). Journal of Insect Conservation 11: 203-207.

Predation of insects by feral cats (Felis silvestris catus) on a heterogeneous oceanic island (La Palma, Canary Islands) was studied. A total of 127 invertebrates were identified in the analysis of 500 scats (100 from each habitat of the Island). Invertebrates appear in 18.00% of the scats, representing an insignificant percentage of the total consumed biomass by feral cats on La Palma Island (0.05%). Insects were the most common invertebrate prey both in percentage of occurrence (90.6%) and invertebrate biomass (93.53%), with a total of 115 prey items. Orthoptera, Lepidoptera and Coleoptera were the main prey groups. Among the five main habitats present in La Palma Island, the temperate forest shows the lowest consumption of invertebrates, although insect consumption did not show statistical differences. However Orthoptera and Lepidoptera were more frequently preyed on in the pine forest and in the xerophytic shrub, respectively. Moreover, applying the Simplified Morisita index, a different insect composition of the diet was observed among habitats. Although, none of insects predated by feral cats are threatened, the identification of invertebrate component of the feral cats’ diet is an important tool for the correct understanding of predation significance and to prevent damage to endangered insect species.

8 Medina, F.M. & M. Nogales. 2009. A review on the impacts of feral cats (Felis silvestris catus) in the Canary Islands: implications for the conservation of its endangered fauna. Biodiversity and Conservation 18: 829-846.
Feral cats have been directly responsible for the extinction of numerous species on islands worldwide, including endemic species of mammals, birds and reptiles. The diet of feral cats in the main habitats of the Canary Islands, as generally occurred on oceanic islands, is mainly composed of introduced mammals, and native species of birds, reptiles and insects. The impact of feral cat upon the endangered species was assessed by evaluating their relative abundance in the cats’ diet and by considering their current conservation status. A total of 68 different preys were identified at species level in all studies carried out in the Canary Islands (5 mammals, 16 birds, 15 reptiles and 32 invertebrates). From all the species preyed by feral cats in the Canary Islands, only four of them are considered threatened by the IUCN Red List of Threatened Species: one endemic bird Saxicola dacotiae and three endemic giant lizards, Gallotia simonyi, Gallotia intermedia, and Gallotia gomerana. Although some efforts on management control have been carried out, it is necessary to enforce these conservation activities on those areas of Tenerife, La Gomera and El Hierro where giant lizards are still present. Furthermore some local areas where endangered bird species are highly predated should be protected. Nevertheless, it is important to take into account the presence of other introduced species such as rats, mice or rabbits in order to avoid problems derived from the hyperpredation process and mesopredator release effect.

9 Nogales, M. & F.M. Medina. 2009. Trophic ecology of feral cats (Felis silvestris f. catus) in the main environments of an oceanic archipelago (Canary Islands): An updated approach. Mammalian Biology 74: 169-181. 
The diet of feral cats in the main habitats of the Canary Islands is composed of introduced mammals, birds, reptiles and insects. However, introduced mammals constitute the main source of biomass consumed, followed in importance by reptiles and birds. PCA analysis of biomass revealed the ordination of three different groups, corresponding to the diet in the laurel forest (La Gomera), thermophilous forest (El Hierro) and one large group that include the rest of habitat types. A similar pattern was observed when these habitats were analyzed in a single island (La Palma). Oryctolagus cuniculus was an important prey in practically all habitats, while Rattus rattus was frequently captured in the laurel forest, Mus musculus domesticus in the open shrubs (both xeric and high mountain), reptiles (mainly lizards genus Gallotia) in the open habitats of Tenerife, birds play a relative role in forest habitats, and large invertabrates (basically Orthoptera and Coleoptera) in the three forest habitats and in the xerophytic shrub of Fuerteventura. Morisita’s index of similarity of diet showed maximum differences between the forest habitats (pine and thermophilous vs. laurel forest), indicating an important heterogeneity in the diet of feral cats in these environments. Shrub habitats showed smaller values of Levin’s niche breadth than those from the forest habitats, showing a broader diet in the latter. Lastly, the diet of feral cats on the Canary Islands follows the general pattern of other islands located at similar latitude and mainly composed by rabbits and mice. However, specific preys such as lizards, rats or birds, play an important role in particular habitats in which they are abundant.

10 Medina, F.M. & M. Nogales. 2007. Habitat use of feral cats in the main environments of an Atlantic Island (La Palma, Canary Islands). Folia Zooliga 56(3): 277–283

In this study we assess the habitat use of feral cats in the five main habitats represented on La Palma Island in the Canary Islands. We determined habitat use by the presence of faeces. Faeces persistence time was significantly different between habitats, being clearly lower in the laurel forest (the wettest) than in the other habitats. This humid environment promotes the high presence of invertebrate decomposers such as Isopoda and Diplopoda. Once the effect of differential persistence times for faeces among the different habitats was controlled for, data obtained indicated that feral cats showed no differences in the use of the five main habitats present on La Palma Island. Although cats selected closed habitats more frequently than open ones, because they prefer cover for hunting, no statistical differences were found in the island habitats studied.

11 Medina, F. M., M. López-Darias & M. Nogales. 2008. Food habits of feral cats (Felis sylvestris f. catus, L. 1758) in insular semiarid environments (Fuerteventura, Canary Islands). Wildlife Research 35: 162-169.
In this study, we present the first data on diet and impacts of feral cats on a semiarid island (Fuerteventura, Canary Islands). A total of 614 prey was identified in the 209 scats analysed. Introduced mammals, specially rabbits and mice, were the most consumed vertebrate prey and constituted more than 90% of biomass. Barbary ground squirrels, Algerian hedgehogs, and rats were preyed upon less even though they were abundant on the island. Invertebrates, mainly Orthoptera, Coleoptera, Hymenoptera and Odonata, were the second most important prey items (in terms of actual numbers) but they contributed only minimally with respect to biomass (<1.1%). The presence of terrestrial molluscs in the diet was interesting because they are a rare prey in an insular context. Birds and reptiles occurred at a low frequency. A total of 677 seeds was counted, mainly belonging to Lycium intricatum (Solanaceae) and two unidentified plant species. Levin’s niche breadth was narrow due to the high consumption of mammals. Morisita’s index showed a similar trophic overlap in diet with respect to the other xeric habitats of the Canarian archipelago. Considering that more than 90% of biomass corresponded to introduced mammals, we conclude that feral cats are not having a large direct impact on the native prey species.

12 Medina, F.M. y M. Nogales. 1993. Diet of the feral cat (Felis catus L.) in the xerophytic zone of the Macizo de Teno (Northwestern Tenerife. Doñana Acta Vertebrata, 20 (2): 291-297

The diet of the Feral cat (Felis catus) was studied in the xerophytic zone of Tenerife, by analyzing 200 scats. A total of 477 prey items were identified. Mammals (Oryctolagus cuniculus, Mus musculus and Rattus  sp.) constitued the basis of the diet occurring in 86% of the samples and representing 85,4% of the consumed biomass. Reptiles occurred in 57% of the scats and representing 13,6% of the biomass. The lizard (Gallotia galloti), endemic of the western Canary Islands, was frequenetly captured, occurring in 54% of the scat groups and representing 13% of the total biomass. This percentage is very importan in the world context of the diet. Birds and insects (frequence of occurrence less than 5%) were insignificant in the diet.


Cabo Verde
13 Medina, F. M., P. Oliveira, P. Geraldes, J. Melo & N. Barros. 2012. Diet of feral cats Felis catus L., 1758 on Santa Luzia, Cape Verde Islands. Zoologia Caboverdiana 3 (2): 67-73.

The diet of feral cats Felis catus on Santa Luzia, Cape Verde Islands, was studied. A total of 147 prey items were identified during the analysis of 26 scat groups collected during the summer of 2010. House mouse Mus musculus was the most important prey, both in percentage of biomass and number of preys consumed (89.7% and n= 117, respectively). Reptiles were the second most important prey, represented by one skink species (Chioninia stangeri) and an unidentified gecko species. The remainder of the identified prey consisted of one bird species (Passer iagoensis) and one undetermined Tettigoniidae species (Insecta). No endangered species were identified in scats of this introduced predator, but future surveys must be carried out to further avoid threats to the island’s biodiversity.