- Ocelots suffered severe declines in the 1960s and 70s due to hunting, but populations have rebounded since the international fur trade was banned. Now, heavy deforestation and increasing human activity across their range threaten to put this elegant creature back on the endangered list.
- Researchers collected images from hundreds of camera traps set across the Amazon basin and analyzed the effect of different habitat characteristics on the presence of ocelots. Statistical modeling revealed the cat’s preference for dense forests and a dislike of roads and human settlements.
- Experts say ocelots may also be responding to human activity and forest degradation in ways that camera traps cannot easily detect, such as changing how and when they use a particular habitat. The study looked at ocelot behavior in protected and forested habitat, not in degraded landscapes.
- Ocelots are considered ambassador species for their forest ecosystem, and studies like this give support to maintaining protected areas, which are increasingly under threat from agricultural expansion and other human activities.
Ocelots living the Amazon basin prefer dense forest and avoid roads and human settlements, according to the largest ever camera trap study of this illusive wildcat, published in the journal Ecology and Evolution earlier this year.
The ocelot (Leopardus pardalis) is a medium-sized spotted cat found across the southwestern United States, central and South America.
The species suffered severe declines in the 1960s and 70s because of hunting for the fur trade, but has recovered since the trade was banned, and they are now listed as of “least concern” by the IUCN Redlist. However, heavy deforestation and increasing human activity across their range threaten to put this shy elegant creature back on the endangered list.
To better understand how ocelots respond to changes in their habitat, Bingxin Wang and a team of researchers from the Wildlife Conservation Research Unit at the University of Oxford collaborated with Brazilian researchers to collect images from nearly 900 camera traps, along with environmental data such as tree cover, elevation, and the proximity to rivers, roads and human settlements at twelve sites across the Amazon basin in Brazil in the states of Amazonas, Rondônia, Mato Grosso, and Pará, as well as the state of Rio de Janeiro.
The authors used statistical modelling to analyse and understand the creatures’ habitat choices, which revealed a preference for dense forests near rivers and a dislike of roads, settlements, and steep slopes
“This project showcases how multiple conservation organizations can collaborate to reveal the habitat preference of an important yet previously neglected species,” said conservation researcher Cedric Tan, who supervised the work. The study represents the largest effort to monitor ocelot numbers and behavior using camera traps ever conducted, totalling more than 40,000 days of recording between 2010 and 2017. “Unlike larger, more charismatic felids, such as jaguar and puma, ocelot gain less attention from researchers and the public,” noted Wang.
The researchers found that ocelots were more likely to occupy habitat with denser forest cover farther away from roads and human settlements — sites that are likely to have plenty of prey and relatively few humans. The results mirror those of studies on other small wild cats, such as clouded leopards (Neofelis nebulosa), which also prefer dense, unfragmented forests.
Forest carnivores are expected to be highly sensitive to forest fragmentation and deforestation because of their restricted diet and the need for large home ranges. When apex predators such as jaguars (Panthera onca) are lost from a habitat, more adaptable mesopredators like ocelots, which form the next rung down on the food chain, may play an even more important role in stabilizing the ecosystem by keeping prey populations in check. For this reason, as well as their charisma and public appeal, they are considered “ambassador species” for their whole ecosystem.
Ocelots, like many other medium-sized predators, are known for their adaptability, and at the twelve sites included in this study they were extremely common —cameras recorded more than 334 sightings across the 7-year study. The “ocelot is able to thrive wherever there are forests populated with suitable prey,” said Wang. However, she warns against complacency over conserving this ambassador species and it’s habitat — the study did not include deforested or heavily degraded habitats, where ocelots are likely to be more severely affected.
“Even though ocelots are seen as a flexible and adaptable species, the results show that they are still responding to human pressure,” commented Guilherm Ferreira, an experienced camera-trapper studying large mammal populations in southeastern Brazil. “Although this negative effect is intuitive, it is important to show it empirically,” he said.
The broad adaptability of the ocelot may explain why several of the characteristics that the team measured, such as habitat fragmentation and slope gradient, had only very weak effects on ocelot habitat use. The twelve sites included in the study were all located within protected areas or on private land, which the team acknowledges may have limited their ability to detect major impacts due to deforestation, forest fragmentation and human activity.
“This study would have [detected] a greater impact if there was more variation in their sites by including secondary forest… fragmented habitats and potentially even sites that have been converted to agriculture,” said Emily Madsen, a conservation biologist and camera trap expert from University College London.
But experts say there may be other ways in which ocelots are responding to these variables without leaving a habitat completely. “Adapting to human pressures can also often mean that [animals] change the way they use the available habitat,” said Madsen. This might involve sticking to thicker vegetation in areas of higher human presence, or becoming more strongly nocturnal to avoid daytime human activity, she said. “Important aspects of the species’ ecology and behaviour cannot be revealed using camera trap surveys,” agreed Ferreira.
Weaker, more nuanced relationships between habitat characteristics and ocelot behavior might also be evident at different scales. The present study considered habitat characteristics with in a 500 meter (1640 feet) radius of each camera trap, but evidence from a variety of species shows that animals do not respond to all habitat characteristics at the same spatial scale. For instance, cheetah behavior is influenced by the presence of human activities more than a kilometer (0.62 miles) away, whereas they respond to environmental characteristics on a much smaller scale of up to 200 meters (656 feet).
Accidentally caught on camera
Camera traps are indiscriminate about which species’ images they capture, so devices set up for one purpose can often yield useful data about other species. By pooling data from researchers across Brazil, this study was able to take advantage of camera traps that were set as part of previous research on other species; a low-cost and relatively quick way to gather data that can aid in conservation planning. However, recycling data in this way comes with some limitations — you can’t choose where or how to set up the camera traps, for example.
Madsen suggested that this may have constrained the team’s analysis. For example, the authors used a statistical technique known as occupancy modeling to understand how habitat variables such as tree density and proximity to a road influence the presence of ocelots in a particular area. “Methods which allow us to calculate densities would probably be more informative,” and might have detected weaker effects of habitat characteristics that occupancy modelling missed, she suggested.
“Density is more informative than occupancy and should be used as a metric whenever possible,” agreed Ferreira, “[T]he problem is that you need more data to estimate density.” To make such calculations, the authors would have needed to identify individual ocelots, which is possible, but only when utilizing the best quality photos — limiting the analysis capacity of this “accidental” camera trap data.
“Perhaps, using density [data] the authors would obtain a more refined picture… [N]evertheless, using occupancy [data] as a metric the authors were still able to show, for example, that [decreased] distance from households negatively affects ocelot use of the landscape,” information that can be useful for designing conservation management recommendations for the species, Ferreira said.
This, and other studies demonstrating the negative impact of human activity on biodiversity, emphasize the importance of protected areas, many of which are under threat of being downsized or eliminated due to political pressure from agribusiness lobbyists and the policies of the current Brazilian administration of Jair Bolsonaro. Ocelots’ aversion to humans may make them especially vulnerable to reductions in environmental protection — new roads that carve up the forest also bring more human activity to the fragments that remain.
The camera traps may yet yield more information about ocelot behavior. Wang said that the team hopes to reanalyze the data they’ve gathered, looking at other predators and prey to understand the suitability of different types of habitat found with the whole ecological community.
Citation:
Wang, B., Rocha, D. G., Abrahams, M. I., Antunes, A. P., Costa, H. C., Gonçalves, A. L. S., … & Ramalho, E. (2019). Habitat use of the ocelot (Leopardus pardalis) in Brazilian Amazon. Ecology and evolution, 9(9), 5049-5062. DOI: 10.1002/ece3.5005
Banner image: The ocelot is a solitary feline, active at twilight and after dark. It preys on small mammals, including armadillos, rabbits, rodents, small birds, fish, insects and reptiles. Photo credit: Ucumari Photography / CC BY-NC-ND.
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