Texas ocelots seek large, unbroken swaths of thornscrub

Endangered ­­­ocelots in South Texas prefer to use unfragmented landscapes. Efforts to conserve the imperiled feline should focus on maintaining large patches of woody cover, particularly on private lands, researchers found.

There are just 80 or fewer resident ocelots (Leopardus pardalis) in the U.S., and they are all found in Texas in two separate isolated populations — one on the Yturria Ranch and the East Foundation’s El Sauz Ranch and the other in and around the Laguna Atascosa National Wildlife Refuge.

Habitat fragmentation from agricultural development and urbanization is high near the refuge, which supports a population of typically eight to 14 ocelots, said Jason Lombardi, an assistant professor of research from the Caesar Kleberg Wildlife Research Institute at Texas A&M-Kingsville. The remainder of Texas’ ocelots occur in Willacy and Kenedy counties on private lands such as El Sauz Ranch owned by the East Foundation, a private agriculture research organization that Lombardi says is “leading the charge for ocelot conservation and recovery.” That land contains large, contiguous undisturbed patches of thornscrub that ocelots prefer.

Lombardi led a recent study published in Mammal Research that used camera traps to what determine spatial structure of woody cover ocelots are most likely to use.

He and his colleagues — including TWS member Michael Tewes who spoke to TWS about ocelot conservation in 2019 — have used camera traps to detect ocelots on the El Sauz Ranch since 2011. Those surveys can do more than just provide basic population information, Lombardi said. “We can also use the years and years and years of camera data to help give us better ideas of how the landscape itself is affecting the habitat use patterns of the cats, which will help us inform strategies to help preserve habitat as well as come up with recovery strategies for the cats,” he said.

The results of their surveys were not surprising, Lombardi said. “In South Texas specifically, what we’ve seen over 35 years is that ocelots are really tied to these dense thornscrub forests,” he said. “What we saw year after year after year is that patches that were larger and more regularly shaped were used more often than those that were smaller and had a less regular or irregular shape.” Regularly shaped patches have lower perimeter to area ratios, indicating lower degrees of habitat fragmentation. That means ocelots prefer to use areas that are larger and less fragmented, Lombardi said.

The researchers also found that ocelots were less likely to be detected by camera traps during periods of drought. They suspect this may be due to reduction in rodent populations, which cause the cats to range farther in search of prey.

Lombardi said that the conservation implications of the study are clear: “If we see that there are patches that are fragmented where we have ocelots, then we should work to promote woody cover or habitat restoration to help these patches become larger. As they become larger, they will eventually coalesce and create larger patches that will promote habitat use and dispersal,” he said.

Dispersal could be key for the ocelot’s future in Texas. “We’ve not documented a case of a successful dispersal between the two [Texas] populations in over 35 years, and both populations are severely inbred,” Lombardi said.

Conservationists will have to focus on promoting large patches of woody cover on private lands to recover the ocelot, Lombardi added. “What this research really highlights is the importance of these large private rangelands to ocelot recovery,” he said. “Considering that Texas is 97% privately owned, ocelot recovery is going to have to go through private lands. The future of recovery should be guided through working with private landowners since that’s where 80% of the population is.”