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Feeding behaviour of red fox and domestic cat populations in suburban areas in the south of Paris

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Among medium-sized carnivores, red foxes (Vulpes vulpes) and domestic cats (Felis silvestris catus) are the most abundant species in human-dominated landscapes worldwide. Both are known to be generalist predators that exploit a wide range of prey groups (e.g., mammals, birds, and invertebrates). Identifying red fox and domestic cat predation pressure on shared prey could shed light on their ecological role in shaping wildlife communities in human-dominated landscapes. Here, we assess the seasonal diet of red foxes and domestic cats in terms of composition, breadth, and overlap. Over two years, we collected their scats across three human-dominated study sites: park (n = 220 for foxes and n = 0 for cats), agricultural land (n = 159 for foxes and n = 146 for cats), and managed forest (n = 169 for foxes and n = 47 for cats). We detected similar diet breadth (B) for red foxes and domestic cats (B = 0.32 and B = 0.36, respectively) as well as strong dietary overlap (O = 0.83) between them. Moreover, the diet composition of both predators varied according to the study sites and seasons. Our results confirm the highly flexible trophic behaviour of these carnivores at the study sites, probably as a consequence of prey availability, and also the simultaneity of their predation over the same prey groups. Future studies should simultaneously monitor predator diet as well as predator and prey abundance in human-dominated landscapes to better understand the predatory impact of red foxes and domestic cats.
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Feeding behaviour of red fox and domestic cat populations
in suburban areas in the south of Paris
Irene Castañeda
1,2
&Diane Zarzoso-Lacoste
2,3
&Elsa Bonnaud
2
#Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
Among medium-sized carnivores, red foxes (Vulpes vulpes) and domestic cats (Felis silvestris catus) are the most abundant
species in human-dominated landscapes worldwide. Both are known to be generalist predators that exploit a wide range of prey
groups (e.g., mammals, birds, and invertebrates). Identifying red fox and domestic cat predation pressure on shared prey could
shed light on their ecological role in shaping wildlife communities in human-dominated landscapes. Here, we assess the seasonal
diet of red foxes and domestic cats in terms of composition, breadth, and overlap. Over two years, we collected their scats across
three human-dominated study sites:park (n= 220 for foxes and n=0forcats),agriculturalland(n= 159 for foxes and n= 146 for
cats), and managed forest (n= 169 for foxes and n= 47 for cats). We detected similar diet breadth (B) for red foxes and domestic
cats (B = 0.32 and B = 0.36, respectively) as well as strong dietary overlap (O = 0.83) between them. Moreover, the diet com-
position of both predators varied according to the study sites and seasons. Our results confirm the highly flexible trophic
behaviour of these carnivores at the study sites, probably as a consequence of prey availability, and also the simultaneity of their
predation over the same prey groups. Future studies should simultaneously monitor predator diet as well as predator and prey
abundance in human-dominated landscapes to better understand the predatory impact of red foxes and domestic cats.
Keywords Diet breadth .Diet overlap .Domestic cat .Red fox .Human-dominated landscapes
Introduction
By 2050, more than half of the worlds population will live in
urbanized areas (United Nations 2019). Consequently, under-
standing the functioning of these ecosystems is necessary in
order to preserve both biodiversity and human life quality.
Human-dominated landscapes share a set of general biotic
and abiotic characteristics such as the alteration of species
richness (McKinney 2008), the variation of microclimatic
conditions (Santamouris et al. 2001), the availability of new
resources such as anthropogenic food refuse (Fleming and
Bateman 2018), and the lack or reduced number of large car-
nivores (Crooks 2002; Iossa et al. 2010; Bateman and Fleming
2012). In this context, medium-sized carnivores may be re-
leasedin the absence of top-predators (Crooks and Soulé
1999), thus influencing prey populations through top-down
processes, as already demonstrated at continental (Ripple
et al. 2013) and local scales (Jiménez et al. 2019).
Among medium-sized carnivores, the red fox (Vulpe s
vulpes) is one of the most widespread species (Schipper
et al. 2008), while the domestic cat (Felis silvestris catus)is
one of the most popular pets worldwide. Out of 18.83 million
pets in France, 11.4 million are cats. Moreover, the generalist
trophic behaviour of red foxes and domestic cats makes them
successful species in human-dominated landscapes (Bateman
and Fleming 2012). Red fox diets in urban areas are mostly
characterized by the presence of anthropogenic food refuse
(Harris 1981; Doncaster et al. 1990; Contesse et al. 2004;
Hegglin et al. 2007;Meckstrothetal.2007), while in rural
areas, they are more diversified with mammals and birds
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s11252-020-00948-w) contains supplementary
material, which is available to authorized users.
*Irene Castañeda
irene.castanedagonz@gmail.com
1
Centre dEcologie et des Sciences de la Conservation (CESCO,
UMR 7204), Muséum national dhistoire naturelle, CNRS, Sorbonne
Université, 57 rue Cuvier, 75005 Paris, France
2
Ecologie Systématique et Evolution, Université Paris-Saclay, CNRS,
AgroParisTech, 91405 Orsay, France, Université Paris-Saclay,
91405 Orsay, France
3
Unité Ecologie et Dynamique des Systèmes Anthropisés
(UMR7058 CNRS), Université de Picardie Jules Verne, 1 rue des
Louvels, 80037 Amiens Cedex 1, France
https://doi.org/10.1007/s11252-020-00948-w
Published online: 21 February 2020
Urban Ecosystems (2020) 23:731–743
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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Diet studies are frequently used to improve understanding of predator ecology, potential effects of carnivores on prey populations, and competition among predators. However, field identification of carnivore scat typically relies on scat morphology, size, and contents resulting in possible subjective predator identification and potentially biased results. Advancements in noninvasive genetic sampling allow for molecular identification of predator scat, eliminating many issues associated with field identification methods. We collected scat samples once per month from June 2011 to May 2012 in western Virginia, USA, using morphological characteristics for field identification of the predator. We then used mitochondrial DNA to identify the predator species of each scat and identified prey remains visually. Using confusion matrices, we found a range of accuracy in field identification for the 3 target species: coyotes (Canis latrans; 54.0%), bobcats (Lynx rufus; 57.1%), and black bears (Ursus americanus; 95.2%), even though we only considered samples with high-confidence field identification. We found a high coyote false-positive rate (52.7%), indicating we often incorrectly identified scats as coyote (98% of misidentified bobcat scats and 75% of misidentified black bear scats were recorded as coyote in the field). This asymmetrical bias in predator identification resulted in inaccurate estimates of dietary niche breadth and overlap between competitors. Our results suggest that caution should be exercised when interpreting results from studies in which carnivore species are identified by scat morphology. Future studies should employ noninvasive genetic sampling for carnivore scat identification, especially in areas with sympatric predator species that have similar scat morphology.
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Although free-roaming cats can have a significant impact on the environment, and substantial resources have been invested to find humane alternatives for managing free-roaming cat populations, there are no empirical estimates of free-roaming cat population size in medium to large cities. In addition, little is known about factors limiting free-roaming cat population size and distribution. Using Guelph, Ontario, Canada (pop: 120,000; 86.7 km2) as a case-study, we apply replicated distance transect sampling and likelihood-based hierarchical modeling to compare human-mediated landscape patterns of land use, distance to roads, distance to wooded areas, building density and socio-economic status to explain the abundance of free-roaming cats. We then derive an empirical estimate of total population size and present a spatially-explicit prediction of free-roaming cat density across an entire city. Cat abundance was highest in residential areas and lowest in commercial and institutional areas, negatively related to median household income, and positively related to distance from woods and building density. Total population size was estimated to be 7,662 (95% bootstrap CI: 6,145 – 9,966) for Guelph; free-roaming cat density varied from 0 – 49.4 cats/ha. Our estimate overlapped with an independent estimate of indoor-outdoor cats (11,927; 95% CI: 6,361 – 20,989) derived from random surveys of city residents, which implies our distance-transect methodology was relatively robust and unbiased. Our approach used simple geographic information that is readily available for most urban areas in North America and can be applied broadly to inform cat management in urban areas. Finally, our results suggest that free-roaming cat density in cities could be determined by bottom-up processes (e.g. enhanced food availability in residential areas) as well as top-down processes (e.g. enhanced susceptibility to coyote predation near wooded areas) which are typically reserved to explain wildlife populations in natural environments.