Amazon islands as predator refugia: jaguar density and temporal activity in Maracá-Jipioca

Abstract

Limited space on islands usually cannot sustain stable populations of large predators. However, jaguars, the largest cat species in the Americas, unexpectedly occur in the Estação Ecológica Maracá-Jipioca reserve, a system of continental Amazonian islands in the Atlantic Ocean. We investigated jaguar population structure, density, and activity patterns. We placed 25 camera-trap stations across 149.19 km2 and used spatially explicit capture–recapture to estimate density, and Rayleigh’s test to assess activity patterns. We identified 21 individuals (12 females, six males, and three cubs) and estimated an adult density of 6.7 individuals per 100 km2, which equals a population of approximately 43 jaguars. The population is composed mostly of females (66%) in relation to males (33%). Male and female activity patterns overlapped and showed more activity during daytime. The high jaguar density and the presence of females with cubs indicate that these islands are likely natural refugia for jaguars, reinforcing the importance of this protected area for jaguar conservation and possibly challenging the paradigm that large-mammal populations are not feasible in restricted islands.

Impending anthropogenic threats and protected area prioritization for jaguars in the Brazilian Amazon

“…88 , ref. 89 —with the values within a 5 km radial buffer at the same geographic coordinates derived from ref. 25 .…”

Big cats like water: occupancy patterns of jaguar in a unique and insular Brazilian Amazon ecosystem

“…With annual rainfall ranging from 2,300 to 2,800 mm (Am climate type, according to Köppen's climate classi cation) and limited variation in elevation (mean altitude = 3 meters), the islands have extensive ooded areas and lagoons (Tavares 2014;Ferreira et al 2017). The distance from the islands to the continental coast ranges from 6-10 kilometers (Ferreira et al 2017;Duarte et al 2022). The vegetation on the islands is primarily composed of mangroves, grasslands, and formations of mixed vegetation (locally called Tesos) consisting of mangrove trees (Rhizophora sp.…”

“…Together, the islands harbor at least 11 vertebrate orders that have been reported as jaguar prey, including tegu (a lizard; Salvator merianae), shorebirds, rodents, and ungulates. However, no other species of terrestrial carnivore inhabits the islands, probably due to spatial limitations and the competitive pressure imposed by jaguar (Duarte et al 2022). Therefore, the functional role of the jaguar as a predator in this system is irreplaceable.…”

“…Covering ~ 60,000 ha, the two main islands harbor high concentrations of jaguar prey (e.g., sh, crocodilians, turtles, and wetland birds) (Ferreira et al 2017) and, consequently, host an abundant population of jaguars (6.67 individuals/100 km²), whose occupancy patterns are probably in uenced by the hydrodynamics of the islands and its in uence on water-dependent prey (Duarte et al 2022). Despite the spatial limitations of the islands, collectively they provide a wide array of food resources, both aquatic and terrestrial, which can be exploited by opportunistic predators such as jaguars (Jędrzejewski et Therefore, to better understand how jaguars have adapted to this unique insular ecosystem and to provide information supporting a sustainable management plan for ESEC-MJ, it is fundamental to understand the processes driving habitat use by the jaguar and to assess their occupancy patterns.…”

“…Our study aims to ll this knowledge gap by assessing if habitats at the interface of land and water, namely those along lagoons, channels, and beaches, together with the occurrence of the most consumed prey species, potentially in uence the detectability and occupancy patterns of jaguars in ESEC-MJ. We hypothesized that jaguars would be more easily detected in habitats with reduced vegetation cover, such as beaches, and those dominated by perennial aquatic environments (e.g., lagoons) (Duarte et al 2022).…”