Multiscale habitat relationships of a habitat specialist over time: The case of ocelots in Texas from 1982 to 2017

Abstract

Evaluating temporal trends in habitat and behavioral responses is critical for conservation, yet long‐term monitoring studies are rare. We used a 35‐year dataset (1982–2017) to assess multiscale habitat use and selection by an endangered carnivore, the ocelot (Leopardus pardalis), in South Texas, USA. We used a time series of remotely sensed imagery to map changes in availability of woody cover, habitat critical to ocelots that has diminished due to anthropogenic development and increased road infrastructure. Our objectives were to characterize habitat relationships, predict high‐quality habitat, and assess behavior with changing environmental conditions. We fit functional response (third order) and individual‐specific resource selection (second order) functions to assess multiscale habitat use of vegetation cover and roads. Within home ranges, ocelots used woody cover greater than availability. Ocelots used areas near roads in proportion to availability, with minor exceptions. We observed changes in habitat use by ocelots across time with higher proportions of woody and non‐woody cover used in later time periods. Average availability of woody cover decreased in the study area between the 1980s and 2010s (0.44 in 1985 to 0.39 in 2015, p < 0.001), and ocelots used areas with a higher proportion of woody cover (≥0.48) farther from high‐traffic roads compared to availability. High‐quality ocelot habitat was consistently predicted in areas with high proportions of woody cover, while areas closer to high‐traffic roads were consistently predicted as non‐habitat. The extent of predicted habitat never exceeded 47% (1515 km2) of the study area, illustrating the confined nature of ocelot habitat. Our assessment of multiscale habitat use demonstrated that higher order selection processes likely truncate resource gradients within home ranges. Ocelots did not avoid roads as expected within home ranges, which is a likely mechanism for vehicle‐induced mortality. Private lands contained ≥79% of predicted high‐quality habitat over time. Therefore, the future of ocelots in the United States relies on private land stewardship. Insights gained from these analyses can advance habitat conservation and mitigation of road mortality for ocelot populations.

Spatial capture-recapture and LiDAR-derived vegetation metrics reveal high densities of ocelots on Texas ranchlands

“…Bennett et al (2018) reported that more than 60% of threatened and endangered species occur on private lands. Working on private lands can contribute to a better understanding of landscape resiliency (Samson et al, 2021, Donnelly et al, 2016, habitat or genetic connectivity (Hooker et al, 2021;Veals et al, 2022), and habitat preservation and restoration efforts (Burger et al, 2019;Cortez, 2021;Kobilinsky, 2022). Recovery planning for endangered species, however, requires knowledge of the best available science and if areas are not surveyed, may lead to inadequate information and strategies (Hilty and Merenlender, 2003;Burger et al, 2019).…”

“…In South America, ocelots are listed as Vulnerable in Brasil, Colombia, and Argentina, and in North America, they are listed as Endangered in Mexico and the United States (Hunter, 2015; International Union for the Conservation of Nature 2022). Ocelots occur in heterogenous forested landscapes and often select for areas of mixed and dense forest and vegetation (Hunter, 2015;Wang et al, 2019;Lombardi et al, 2021;Lombardi et al, 2022;Veals et al, 2022). Further, their niche space has been debated with some referring to them as generalists (Paolino et al, 2018, Moreno-Sosa et al, 2022 and others as specialists (Shindle and Tewes, 1998;Haines et al, 2006a;Horne et al, 2009).…”

“…In the mid-1980s, it was estimated that fewer than 120 ocelots remained in Texas, but no formal population size estimates were made at the time. Over the last 40 years, subjective estimates of population size have fluctuated from 80 to 120, less than 100, and more recently less than 80 (Tewes, 1986;Haines et al, 2006b; U. S. Fish and Wildlife Service, 2016;Lombardi et al, 2021;Veals et al, 2022). Today, ocelots exist in two isolated breeding populations in coastal southern Texas with no known genetic exchange between the two populations (Janecka et al, 2016).…”

“…The smaller, Refuge Ocelot Population (16-20 based on known individuals; H. Swarts, USFS pers. com), is located 25 km south of Laguna Atascosa National Wildlife Refuge and surrounded by extensive agriculture and urban development (Veals et al, 2022). Inbreeding depression and loss of genetic diversity (Janecka et al, 2016), land conversion (Lombardi et al, 2020a;Veals et al, 2022), and road mortality (Blackburn et al, 2021) have continued to negatively affect ocelot populations in Texas.…”

“…com), is located 25 km south of Laguna Atascosa National Wildlife Refuge and surrounded by extensive agriculture and urban development (Veals et al, 2022). Inbreeding depression and loss of genetic diversity (Janecka et al, 2016), land conversion (Lombardi et al, 2020a;Veals et al, 2022), and road mortality (Blackburn et al, 2021) have continued to negatively affect ocelot populations in Texas. Currently, there has yet to be an updated formal analysis using SECR models to estimate local population density and population size in any part of the ocelot's geographic range in Texas.…”