Age‐specific foraging strategies among pumas, and its implications for aiding ungulate populations through carnivore control

Loss of Earth's old, wise, and large animals

Earth's old animals are in decline. Despite this, emerging research is revealing the vital contributions of older individuals to cultural transmission, population dynamics, and ecosystem processes and services. Often the largest and most experienced, old individuals are most valued by humans and make important contributions to reproduction, information acquisition and cultural transmission, trophic dynamics, and resistance and resilience to natural and anthropogenic disturbance. These observations contrast with the senescence-focused paradigm of old age that has dominated the literature for more than a century yet are consistent with findings from behavioral ecology and life history theory. In this work, we review why the global loss of old individuals can be particularly detrimental to long-lived animals with indeterminate growth; those with increasing reproductive output with age; and those dependent on migration, sociality, and cultural transmission for survival. Longevity conservation is needed to protect the important ecological roles and ecosystem services provided by old animals.

Relationship between tooth macrowear and jaw morphofunctional traits in representative hypercarnivores

The mammalian adult dentition is a non-renewable resource. Tooth attrition and disease must be accommodated by individuals using behavioral, physiological, and/or musculoskeletal shifts to minimize impact on masticatory performance. From a biomechanical perspective, the musculoskeletal system becomes less efficient at producing bite force for a given amount of muscle input force over an individual's life, because tooth-food contact area increases as cusps wear. In this study we ask the question: does mandibular biomechanical performance show evidence of compensation with increasing tooth wear? We use representative taxa of three carnivoran ecomorphologies (meat specialist, scavenger, bone cracker) as a study system to compare morphofunctional data on tooth macrowear, jaw depth, bite mechanical efficiency, and jaw stress during biting. No significant shifts in adult mandibular corpus dimensions occurs in the sampled taxa as canine and carnassial teeth wear. In bone cracking spotted hyenas carnassial biting mechanical efficiency increases significantly with increasing tooth wear, with no significant change in mandibular stress. Analyses of the fossil carnivore Hyaenodon suggests an increase in canine biting efficiency with increased tooth wear, but this may reflect interspecific variation or phylogenetic contingency rather than a life history shift. Overall, these findings indicate that scavenging hyaenids and felid meat specialists do not exhibit morphofunctional compensation for the decreased mechanical capability of worn and dull teeth. Behavioral modifications, rather than musculoskeletal adjustments, may instead play a major role in maintaining food acquisition and processing capabilities for individuals surviving into advanced ontogenetic age and tooth wear. These observations highlight the mammalian masticatory system as having a dynamic performance profile through its useful lifespan, and encourage a more nuanced understanding of past and present carnivore guilds by considering wear-dependent performance changes as a possible source of selection.

Season, prey availability, sex, and age explain prey size selection in a large solitary carnivore

Prey selection is a fundamental aspect of ecology that drives evolution and community structure, yet the impact of intraspecific variation on the selection for prey size remains largely unaccounted for in ecological theory. Here, we explored puma (Puma concolor) prey selection across six study sites in North and South America. Our results highlighted the strong influence of season and prey availability on puma prey selection, and the smaller influence of puma age. Pumas in all sites selected smaller prey in warmer seasons following the ungulate birth pulse. Our top models included interaction terms between sex and age, suggesting that males more than females select larger prey as they age, which may reflect experiential learning. When accounting for variable sampling across pumas in our six sites, male and female pumas killed prey of equivalent size, even though males are larger than females, challenging assumptions about this species. Nevertheless, pumas in different study sites selected prey of different sizes, emphasizing that the optimal prey size for pumas is likely context-dependent and affected by prey availability. The mean prey weight across all sites averaged 1.18 times mean puma weight, which was less than predicted as the optimal prey size by energetics and ecological theory (optimal prey = 1.45 puma weight). Our results help refine our understanding of optimal prey for pumas and other solitary carnivores, as well as corroborate recent research emphasizing that carnivore prey selection is impacted not just by energetics but by the effects of diverse ecology.

Differential provisioning roles, prey size, and prey abundance shape the dynamic feeding behavior of gray wolves

The demands of raising dependent young can influence the feeding behaviors of social carnivores, especially for individuals that are primarily responsible for provisioning young. We investigated how the feeding and provisioning behavior of a social carnivore, gray wolves (Canis lupus), are connected and shaped by extrinsic and intrinsic factors, and whether and how these patterns changed throughout the pup-rearing season (April-August). We found breeding wolves had shorter handling times of prey, lower probability of returning to kills, and greater probability of returning to homesites after kills compared to subordinate individuals. However, the feeding and provisioning behaviors of breeding individuals changed considerably over the pup-rearing season. Wolves had longer handling times and returned to provision pups directly after kills less frequently as annual prey abundance decreased. These patterns indicate that adult wolves prioritize meeting their own energetic demands over those of their pups when prey abundance decreases. We suggest that differential provisioning of offspring based on prey abundance is a behavioral mechanism by which group size adjusts to available resources via changes in neonate survival.

Dietary similarity among jaguars (Panthera onca) in a high-density population

Prey remains found in carnivore scats provide generalised dietary profiles of sampled populations. The profile may be biased if individual diets differ and some individuals are over- or under-represented in the sample. Quantifying individual contributions allows us to recognise these potential biases and better interpret generalised profiles. Knowing the dietary differences or similarity between individuals can help us to understand selection pressures and identify drivers of distribution and abundance. Using the results of individual faecal genotyping, we re-interpreted our previously-published generalised dietary profile of an elusive, neotropical felid, the jaguar (Panthera onca; Foster et al. (2010)). We quantified individual sample sizes, assessed whether the generalised profile was influenced by the inclusion of scats originating from the same individual and prey carcass (pseudo-replication), and quantified the distribution of prey species among individuals. From an original sample of 322 jaguar scats from a high-density jaguar population in Belize, we identified 206 prey items (individual prey animals) in 176 independent scats representing 32 jaguars (26 males, 3 females, 3 unknown sex). The influence of pseudo-replication in the original dietary profile was minimal. The majority of scats (94%) came from male jaguars. Eight males accounted for two-thirds of the prey items, while 24 jaguars each contributed <5% of the prey items. With few exceptions, the jaguars followed the same broad diet, a 2:1:1 ratio of nine-banded armadillos (Dasypus noveminctus), other vertebrates ≤10kg, and ungulates, primarily peccaries (Tayassu pecari and Pecari tajacu). We noted prey switching between wild and domestic ungulates for individuals spanning protected forests and farmland. This first scat-based study exploring individual variation in jaguar diet highlights the importance of armadillos and peccaries for male jaguars in Belize, the need for research on their roles in supporting high-density jaguar populations, and the need for more data on female diet from across the jaguar range.

Kill rates and associated ecological factors for an apex predator

Kill rates and functional responses are fundamental to the study of predator ecology and the understanding of predatory-prey dynamics. As the most widely distributed apex predator in the western hemisphere, pumas (Puma concolor) have been well studied, yet a synthesis of their kill rates is currently lacking. We reviewed the literature and compiled data on sex- and age-specific kill rate estimates of pumas on ungulates, and conducted analyses aimed at understanding ecological factors explaining the observed spatial variation. Kill rate studies on pumas, while numerous, were primarily conducted in Temperate Conifer Forests (< 10% of puma range), revealing a dearth of knowledge across much of their range, especially from tropical and subtropical habitats. Across studies, kill rates in ungulates/week were highest for adult females with kitten(s) (1.24 ± 0.41 ungulates/week) but did not vary significantly between adult males (0.84 ± 0.18) and solitary adult females (0.99 ± 0.26). Kill rates in kg/day differed only marginally among reproductive classes. Kill rates of adult pumas increased with ungulate density, particularly for males. Ungulate species richness had a weak negative association with adult male kill rates. Neither scavenger richness, puma density, the proportion of non-ungulate prey in the diet, nor regional human population density had a significant effect on ungulate kill rates, but additional studies and standardization would provide further insights. Our results had a strong temperate-ecosystem bias highlighting the need for further research across the diverse biomes pumas occupy to fully interpret kill rates for the species. Data from more populations would also allow for multivariate analyses providing deeper inference into the ecological and behavioural factors driving kill rates and functional responses of pumas, and apex predators in general.