Extensive aquatic subsidies lead to territorial breakdown and high density of an apex predator

Abstract

Energetic subsidies between terrestrial and aquatic ecosystems can strongly influence food webs and population dynamics. Our objective was to study how aquatic subsidies affected jaguar (Panthera onca) diet, sociality, and population density in a seasonally flooded protected area in the Brazilian Pantanal. The diet (n = 138 scats) was dominated by fish (46%) and aquatic reptiles (55%), representing the first jaguar population known to feed extensively on fish and to minimally consume mammals (11%). These aquatic subsidies supported the highest jaguar population density estimate to date (12.4 per 100 km2) derived from camera traps (8,065 trap nights) and GPS collars (n = 13). Contrary to their mostly solitary behavior elsewhere, we documented social interactions previously unobserved between same-sex adults including cooperative fishing, co-traveling, and play. Our research demonstrates that aquatic subsidies seen in omnivores can be highly influential to obligate carnivores leading to high population density and altered social structure.

Smoothing splines of apex predator movement: Functional modeling strategies for exploring animal behavior and social interactions

“…Across the three plots provided, we can develop a short narrative of a few major movement characteristics. Within their respective time domains, most of the 7 jaguars have stable fluctuations in position within their territories (with some clear overlap in territories) (Eriksson et al, 2021 ; Fontes et al, 2021 ). However, Jaguar 81 (male, age = 4 years), the jaguar with the longest monitoring window, makes a significant territorial transition from residing in the same region as Jaguar 88 (female, age = 5 years) to the territory of Jaguar 12 (female, age = 4 years).…”

Wildfires Disproportionately Affected Jaguars in the Pantanal

“…Moreover, the available estimates for jaguar abundance we used 33 are very conservative and probably underestimated jaguar populations from the Pantanal by a maximum of 3 jaguars/100 km 2 . However, the reported density of jaguars may reach up to 12.4 jaguars/100 km 2 in northern PAs 44,45 and up to 6.5-7 jaguars/100 km 2 in the southern Pantanal farms 5,46,47 . Considering that PAs in the northern Pantanal were severely damaged by the 2020 fires, our results show conservative figures for the actual number of jaguars affected by fires.…”

“…The displacement, injuries, and deaths caused by fire to animals within PAs are worrying because these areas are reportedly richer in diversity and biomass 62,63 (including higher jaguars densities 33,44,64 ) and are fundamental to safeguarding biodiversity and ensuring the long-term provision of ecosystem services 65,66 . Protected areas provide larger continuous areas of natural vegetation cover and limit contact with humans.…”

“…In the Pantanal, jaguar HRs are smaller 32,45,60 and population densities are high 5,[44][45][46][47] because the biome is a highly productive system 42,44,61 , with an abundance of prey species and quality habitat, thus allowing jaguars to meet their spatial needs using smaller areas 32,45,60 . However, a trend of increasing drought, rising temperatures, and repeated occurrences of exceptional fires would weaken the Pantanal's resilience 19,31 .…”

“…Protected areas provide larger continuous areas of natural vegetation cover and limit contact with humans. However, although some PAs support up to 12.4 jaguars/100 km 2 (e.g., Taiamã Ecological Station -TES) 44 , the Pantanal PAs alone would not support viable jaguar populations for more than 50 years 64 . Therefore, sustainable management that allows coexistence in private lands is also fundamental for the conservation of jaguars in the Pantanal [5][6][7][8] .…”