Precipitation and prey abundance influence food habits of an invasive carnivore

Abstract

Invasive predators threaten biodiversity worldwide, and generalist invasive predators are often more successful due to their broad diets. Predation patterns can be influenced by prey abundance, prey preference, and climate, and understanding these relationships is integral to conserving native prey species. We examined stomach contents of 2882 feral cats Felis catus from San Clemente Island, California, to assess how their diets varied annually and seasonally, and how precipitation and prey abundance influenced predation patterns. Rodents were found in 95% (n = 2589) of stomachs containing prey. The endemic San Clemente deer mouse Peromyscus maniculatus clementis was the most prevalent prey species and was found in 85% (n = 2589) of stomachs containing prey. Consumption of rodents, lizards, and birds varied annually. In years following dry winters, consumption of rodents decreased and consumption of lizards increased. This had a particularly strong effect on endemic night lizards Xantusia riversiana reticulata with 20.4% (n = 1952) of non-empty cat stomachs containing night lizards following normal years, and 43.7% (n = 602) following dry years. Consumption of rodents peaked in fall, while consumption of lizards and birds peaked in spring. Using rodenticide removed from bait stations as an index of rodent abundance, we found a positive correlation between bait removal and the number of rodents consumed by cats, and a negative correlation between bait removal and the number of lizards consumed by cats. These results suggest that feral cats use rodents as primary prey and lizards as secondary prey, particularly during droughts when rodent abundance is low. Understanding how weather patterns affect invasive species predation patterns will help conservation biologists predict and manage for the effects of invasive species as climate change continues. Furthermore, identifying and quantifying diet pattern seasonality can help managers identify times when sensitive species are vulnerable and plan interventions accordingly.Animal Conservation 23 (2020) 60-71 ª

Trophic ecology of an introduced top predator (Felis catus) on a small African oceanic islet (Santa Luzia, Cabo Verde Islands)

“…Their availability greatly varies between the seasons, being more common in the dry than the rainy period (Geraldes & Melo, 2016). Our results coincide with those from other xeric islands, where rodents were preyed on mostly in the dry seasons (Parsons et al., 2020). However, despite the lower abundance of mice in the rainy season, the lack of seasonal variations in consumption could be due to their high abundance on the island, as described for other prey species abundant elsewhere, such as rabbits (Molsher et al., 1999).…”

“…The general assumption has been that introduced mammals are the main prey on those islands they inhabit, and saurians are a secondary resource (Fitzgerald & Karl, 1979;Konecny, 1987;Molsher et al, 1999;Palmas et al, 2017). Our case study on a small xeric island contrasts with this general pattern in that cats prey upon nonavian sauropsids as their most important protein and water resource, according to findings by Parsons et al (2020).…”

“…Specifically how this may affect endangered species on islands is also of great interest (Bonnaud et al., 2015; Hervías et al., 2014). Indeed, far less comparable work has been done on oceanic islands worldwide (Fitzgerald & Karl, 1979; Furet, 1989; Harper, 2005; Hervías et al., 2014; Konecny, 1987; Parsons et al., 2020).…”

“…Specifically how this may affect endangered species on islands is also of great interest (Bonnaud et al, 2015;Hervías et al, 2014). Indeed, far less comparable work has been done on oceanic islands worldwide (Fitzgerald & Karl, 1979;Furet, 1989;Harper, 2005;Hervías et al, 2014;Konecny, 1987;Parsons et al, 2020). menées à différentes saisons, fournissant des résultats contrastés, les scinques étant les proies principales pendant la saison des pluies et les souris pendant les périodes les plus sèches.…”

Do Invasive Mammal Eradications from Islands Support Climate Change Adaptation and Mitigation?

“…Increased prey resources combined with increasing temperatures are likely to enhance rodent survivorship and reduce metabolic costs of thermoregulation, allowing rodents to divert more resources to reproduction [94,95], increasing the magnitude of their impacts [90]. Invasive species may also shift their diets in response to altered temperature and precipitation patterns [90,96,97]. In some cases, this increased damage to native species and ecosystems will be accompanied by additional socio-economic costs.…”