An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats

<div><h3>Background</h3><p>The diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed mass of each prey species, the consumed prey mass to excrete one scat needs to be determined and corrected for prey body mass because the proportion of digestible to indigestible matter increases with prey body mass. Prey body mass can be corrected for by conducting feeding experiments using prey of various body masses and fitting a regression between consumed prey mass to excrete one scat and prey body mass (correction factor 1). When the diet is expressed as proportions of consumed individuals of each prey species and includes prey animals not completely consumed, the actual mass of each prey consumed by the carnivore needs to be controlled for (correction factor 2). No previous study controlled for this second bias.</p> <h3>Methodology/Principal Findings</h3><p>Here we use an extended series of feeding experiments on a large carnivore, the cheetah (<em>Acinonyx jubatus</em>), to establish both correction factors. In contrast to previous studies which fitted a linear regression for correction factor 1, we fitted a biologically more meaningful exponential regression model where the consumed prey mass to excrete one scat reaches an asymptote at large prey sizes. Using our protocol, we also derive correction factor 1 and 2 for other carnivore species and apply them to published studies. We show that the new method increases the number and proportion of consumed individuals in the diet for large prey animals compared to the conventional method.</p> <h3>Conclusion/Significance</h3><p>Our results have important implications for the interpretation of scat-based studies in feeding ecology and the resolution of human-wildlife conflicts for the conservation of large carnivores.</p> </div

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals

Funding: Hoge Veluwe great tits: the NIOO-KNAW, ERC, and numerous funding agencies; Wytham great tits: Biotechnology and Biological Sciences Research Council, ERC, and the UK Natural Environment Research Council (NERC).The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.PostprintPeer reviewe

Sex and dominance: How to assess and interpret intersexual dominance relationships in mammalian societies

The causes and consequences of being in a particular dominance position have been illuminated in various animal species, and new methods to assess dominance relationships and to describe the structure of dominance hierarchies have been developed in recent years. Most research has focused on same-sex relationships, however, so that intersexual dominance relationships and hierarchies including both sexes have remained much less studied. In particular, different methods continue to be employed to rank males and females along a dominance hierarchy, and sex biases in dominance are still widely regarded as simple byproducts of sexual size dimorphism. However, males and females regularly compete over similar resources when living in the same group, and sexual conflict takes a variety of forms across societies. These processes affect the fitness of both sexes, and are mitigated by intersexual hierarchies. In this study, we draw on data from free-ranging populations of nine species of mammals that vary in the degree to which members of one sex dominate members of the other sex to explore the consequences of using different criteria and procedures for describing intra- and intersexual dominance relationships in these societies. Our analyses confirmed a continuum in patterns of intersexual dominance, from strictly male-dominated species to strictly female-dominated species. All indices of the degree of female dominance were well correlated with each other. The rank order among same-sex individuals was highly correlated between the intra- and intersexual hierarchies, and such correlation was not affected by the degree of female dominance. The relative prevalence of aggression and submission was sensitive to variation in the degree of female dominance across species, with more submissive signals and fewer aggressive acts being used in societies where female dominance prevails. Thus, this study provides important insights and key methodological tools to study intersexual dominance relationships in mammals

Maternal effects on offspring social status in spotted hyenas

Social status is an important phenotypic trait that determines fitness-relevant parameters. In many mammalian societies, offspring acquire a social position at adulthood similar to that held by their mother ("rank inheritance") and thus obtain fitness benefits associated with this status. Mothers may influence the rank of their offspring at adulthood in at least three distinct ways. Firstly, the direct genetic inheritance of maternal traits that influence resource holding potential might predispose offspring to obtain a rank similar to that held by their mother. Secondly, the prenatal maternal environment might influence offspring rank if fetal exposure to maternal androgens is related to maternal status and affects offspring competitiveness. Thirdly, maternal behavioral support, a component of the postnatal maternal environment, may help offspring dominate individuals subordinate to their mother, thereby assisting offspring to acquire a rank similar to that of their mother. Here, we simultaneously test predictions derived from these three potential maternal effects on offspring rank acquisition at adulthood, using cases of offspring adoption in the spotted hyena Crocuta crocuta. We demonstrate that the rank of adopted offspring at adulthood was similar to that of their surrogate mother and that the competitive ability of offspring at adulthood was best explained by postnatal maternal behavioral support. Copyright 2009, Oxford University Press.

Emotions and Cultural Importance Predict the Acceptance of Large Carnivore Management Strategies by Maasai Pastoralists

Management strategies to reduce human-carnivore conflict are most effective when accepted by local communities. Previous studies have suggested that the acceptance depends on emotions toward carnivores, the cultural importance of carnivores, and livestock depredation, and that it may vary depending on the types of strategies and carnivores involved. However, no study so far considered these factors simultaneously to compare their influence on the acceptance of management strategies. We quantified the predictive potential of these factors on the acceptance of three management strategies frequently applied to mitigate human-carnivore conflict: no action, relocation, and lethal control. We interviewed 100 members of the Maasai community in Ngorongoro Conservation Area in Tanzania. We used structured, closed questionnaires and focused on the three large carnivores involved in the most depredation regionally: spotted hyenas (Crocuta crocuta), lions (Panthera leo), and leopards (Panthera pardus). We found that the majority of respondents accepted no action and rejected relocation and lethal control for all three carnivores. The acceptance of the management strategies was strongly influenced by the emotion joy and by the cultural importance of carnivores, and the effects of joy and cultural importance were stronger than the effect of livestock depredation. We conclude that authorities should evaluate the emotions and cultural importance that local communities associate with carnivores when seeking to gain acceptance of management strategies and account for differences between species. Finally, we recommend that future human-carnivore coexistence studies should consider the socio-psychology of local communities and be done longitudinally to detect shifts in cultural, emotional, and ecological factors over time

Scaling‐up RADseq methods for large datasets of non‐invasive samples: Lessons for library construction and data preprocessing

Genetic non-invasive sampling (gNIS) is a critical tool for population genetics studies, supporting conservation efforts while imposing minimal impacts on wildlife. However, gNIS often presents variable levels of DNA degradation and non-endogenous contamination, which can incur considerable processing costs. Furthermore, the use of restriction-site-associated DNA sequencing methods (RADseq) for assessing tho

Determining hormone metabolite concentrations when enzyme immunoassay accuracy varies over time

<p>Data for identifying clusters of samples assayed with similar enzyme immunoassay accuracy (data_for_cluster.txt), modelling the relationship between initial and remeasured metabolite concentrations in a subset of 27 samples (data_for_fit.txt), and applying the standardisation procedure using the complete data set of 138 samples (data_for_standardisation.txt).</p

Prey species and prey body mass provided to cheetahs during 15 feeding experiments, prey mass consumed and scats excreted by cheetahs, prey mass consumed per collectable scat and digestibility of prey species.

<p>Correction factors 1 (CF1) and 2 (CF2) were determined by fitting (1) an exponential regression to consumed prey mass per collectable scat (<i>Q₅</i>) as a function of mean prey body mass provided per feeding experiment (<i>Q₁</i>) ( = CF1) and (2) a peak logarithmic normal function to the number of excreted collectable scats (<i>Q₄</i>) as a function of mean prey body mass provided per feeding experiment (<i>Q₁</i>) ( = CF2). For details see text. ^a 14 mice and gerbils with a total weight of 1.49 kg were eaten entirely, the remaining 66 with a total weight of 2.74 kg were rejected. Calculations were based on the consumed mice and gerbils. ^b each cheetah fed from five subsequently provided squirrels. ^c–f mean kg of collectable scats per cheetah are based on mean weights of six, seven, seven and four collectable scats, respectively, multiplied by the number of collectable scats per cheetah.</p

Determination of the consumed number of prey individuals in a hypothetical example of 100 collectable scats based on CF1 and CF2 derived from the cheetah feeding experiment of this study.

<p>The calculations are shown for two sampling schemes and three hypothetical mean sizes of feeding groups. <i>Q₄</i> is the number of excreted collectable scats per prey individual and cheetah (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038066#pone-0038066-t002" target="_blank">Table 2</a>) and <i>Q₂</i> is feeding group size. For details see text. ^{a, b, c} see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038066#pone-0038066-t002" target="_blank">Table 2</a>.</p