Ecological impact of free-ranging dogs in Poland

Wierzbowska, I. A., Hędrzak, M., Popczyk, B., Okarma, H., & Crooks, K. R. (2016). Predation of wildlife by free-ranging domestic dogs in Polish hunting grounds and potential competition with the grey wolf. Biological Conservation, 201, 1-9.

Although the domestic dog (Canis familiaris) is a ubiquitous exotic predator that can detrimentally affect natural environments, studies on their ecological impact are relatively scarce, particularly at a national scale. We exploited data derived from Polish Hunting Association reports to provide a national evaluation of rural free-ranging dogs in Poland. Our results demonstrate that free-ranging dogs are widespread and abundant, frequently killing wildlife and livestock in Poland and likely exerting intraguild competition with native carnivores such as grey wolves (Canis lupus). On average, hunting club records estimate that over 138,000 rural free-ranging dogs occurred annually in hunting grounds. In addition, nearly 3000 free-ranging greyhounds and their mixed breeds occurred annually on hunting grounds, although greyhound hunting has been banned in Poland and they are legally required to be restrained within fencing. On average, over 33,000 wild animals and 280 livestock were killed by free-ranging dogs on Polish hunting grounds annually. The number of both wild animals and livestock killed by dogs were strongly and positively correlated with the numbers of rural free-ranging dogs recorded on hunting grounds, reflective of their predation pressure. Also, the number of wild animals killed by dogs was positively correlated with estimates of population sizes and harvest levels of wildlife, reflective of prey availability. Dog predation, in conjunction with harvest by humans, may cause unsustainable off-take rates of some game species. Grey wolves, documented within 39 of the 49 Hunting Districts, ate similar prey as dogs, including ungulates and livestock, and killed dogs on hunting grounds, suggesting both resource and interference competition between these sympatric canids. This comprehensive analysis provides important information about the ecological impact of free-ranging dogs and recommendations for alternative legislative and management measures to control their impacts.

Activity and exploration range of house cats in rural areas of central Poland

Goszczynski, J., Krauze, D., and Gryz, J. (2009). Activity and exploration range of house cats in rural areas of central Poland. Folia Zoologica 58, 363–371.  

Domestic cats are the most numerous predators in Poland. They are commonly kept at farms but hardly controlled, so penetrate freely wide range of habitats. The work aimed at determining the range of greatest impact of cats by identifying patterns of their activity and area searching, over daily, monthly and annual cycles. The density index, estimated from transect counts, performed along standard routes, proved to be dependent on temperature, precipitation and time of the day. In spring and summer, cats presented a two-peaked activity pattern, while in cold seasons it was more stable throughout the day. In warm months cats were registered at a further distance from the buildings than in colder ones. The animals were much less active when rain was falling. Cats’ responses on noticing an observer showed that the further they were from the edges of settlements the more timid and cautious they became. The results showed that the potential pressure that cats may exert on their prey is the biggest around dawn and dusk and in summer. During a daytime it is confined to the immediate vicinity of build-up areas.

Space use and intraguild interactions among three opportunistic predators

Krauze-Gryz, D., Gryz, J. B., Goszczyński, J., Chylarecki, P., & Zmihorski, M. (2012). The good, the bad, and the ugly: space use and intraguild interactions among three opportunistic predators—cat (Felis catus), dog (Canis lupus familiaris), and red fox (Vulpes vulpes)—under human pressure. Canadian Journal of Zoology, 90(12), 1402-1413.

Examples of interspecific interactions have been described for mammalian predators, but less is known regarding disturbances of native predator guilds by domestic predators. We investigated intraguild interactions among three opportunistic predators (dog (Canis lupus familiaris L., 1758), cat (Felis catus L., 1758), and red fox (Vulpes vulpes (L., 1758)) co-occurring in the extensive farmlands of central Poland. Their space use was monitored using tracking stations distributed in field and forest plots along a distance gradient from buildings and analyzed using the occupancy-modeling framework. For all three species occupancy decreased with increased distance from buildings, although for the fox the pattern was relatively weak. The occurrence of cats at the stations was higher in the forest than in the field; for fox and dog, there was a strong variation between study plots. For all three predators, the probability of detection was higher during the night than during the day and varied between the seasons; however, the exact patterns were species-specific. The presence of one predator was also linked to the presence of the other two species—generally, a given species was detected more frequently in the absence of the other two species. We recorded spatiotemporal niche segregation among the three species. We conclude that interspecific antagonistic interactions and differences in foraging ecology are the main drivers shaping co-occurrence of the three species in the agriculture landscape.

Cats' diet in rural Poland

Krauze-Gryz, D., J. Gryz, J. Goszczyński. 2012. Predation by domestic cats in rural areas of central Poland: an assessment based on two methods, Journal of Zoology, 288 (4): 260-266

Studies of cat trophic behaviour can be based on collections of the prey brought home or the prey eaten by cats (i.e. analyses of scat/gut contents). Both methods involve biases with respect to palatability, prey size and assessment of hunting rates. Furthermore, these methods are often used on different groups of cats (i.e. house-based vs. feral), thus results are difficult to compare. In the present study, cats from the same area (rural areas in central Poland) were studied by both methods: prey brought home and prey eaten (scat and gut analyses). Both methods identified mammals as the most frequent prey (followed by birds). However, differences occurred in the percentages of the four main vertebrate groups brought home versus eaten by cats: reptiles tended to be brought home, whereas amphibians tended to be eaten. No such difference was found for birds and mammals. Second, the relative proportions of presumably more palatable and presumably less palatable prey differed. The relative proportions of mice and voles (the latter eaten more frequently) and the relative proportions of soricomorphs and rodents (the latter eaten more frequently) were different. Finally, small prey items (i.e. invertebrates) were recorded incompletely for the brought-home method. Overall, the prey-brought-home method underrepresented small prey and underestimated the predation rate for cats, whereas the prey-eaten method was less likely to record unpalatable prey. We thus recommend to combine these two methods to obtain fuller and truer assessment of cat predation.

Cats reduce effective protected area

Wierzbowska, I.A, J.Olko, M.Hędrzak, K.R. Crooks. 2012. Free-ranging domestic cats reduce the effective protected area of a Polish national park, Mammalian Biology - Zeitschrift für Säugetierkunde, 77 (3) 204

Poland's Animal Protection Act, as of 2002, made it legal to shoot free-ranging cats and dogs. The act triggered substantial social debate with opponents arguing that this legislation was weakly supported by scientific evidence of the ecological impacts of free-ranging pets. Our main research goal was to examine the activity of free-ranging domestic cats within a Polish protected area by applying radio-telemetry methods to determine space use and degree of encroachment into the national park. We trapped and radio-tracked 19 animals from three sites (focal households) located in Ojcow National Park (ONP) in southern Poland from June 2003 to March 2006. Annual 100% MCP home range size varied from 0.02 km² to 1.46 km², and was significantly larger for males (mean ± SE = 0.79 ± 0.34 km²; median = 0.53 km²) than for females (mean ± SE = 0.13 ± 0.05 km²; median = 0.13 km²). The distance travelled by individual cats from focal sites did not significantly differ between males (mean ± SE = 232.00 ± 21.05 m; median = 191 m) and females (mean ± SE = 232.50 ± 12.47 m; median = 228 m), with maximum distances of 1.5 km for males and 1.1 km for females. All monitored cats were in close proximity to nature reserves and ranged into protected areas without any human control. Cats living in the households in the park and its surrounding buffer zone, roaming at 200 m and 1000 m radius distances from their households, occupied from 6% to 100% of the park area, respectively. Our results reveal that free-ranging domestic cats roam through and potentially impact the entire national park, thus reducing its effective protected area.