Ecomorphology of the cervid intermediate phalanx and its implications for palaeoenvironmental reconstruction

This paper reports on newly developed ecomorphological models for the cervid intermediate phalanx. Using a geometric morphometric approach, we quantitatively assess the overall gracility of the bone, the depth and concavity of the proximal articulation and the roundness and symmetry of the distal articulation in the intermediate phalanx, to establish relationships between morphology, locomotor behavior and environment. The morphology of the phalanx was found to vary along a gradient from gracile phalanges with shallow proximal articulations in forms adapted to yielding substrate, to robust phalanges with deeper proximal articulations in taxa adapted to firm substrate. Phylogeny and allometry are accounted for using regressions and phylogenetic comparative methods. Although the results indicate phylogeny explains part of the morphological variation, overall the shape of the intermediate phalanx appears mainly driven by differences in function. Consequently, this element promises to be a useful palaeoenvironmental proxy that can be applied on fossil assemblages with cervid remains.

Loss of Migratory Traditions Makes the Endangered Patagonian Huemul Deer a Year-Round Refugee in Its Summer Habitat

The huemul (Hippocamelus bisulcus) is endangered, with 1500 deer split into >100 subpopulations along 2000 km of Andes. Currently occupied areas are claimed-erroneously, to be critical prime habitats. We analyzed historical spatiotemporal behavior since current patterns represent only a fraction of pre-Columbian ones. Given the limited knowledge, the first group (n = 6) in Argentina was radio-marked to examine spatial behavior. Historically, huemul resided year-round in winter ranges, while some migrated seasonally, some using grasslands >200 km east of their current presence, reaching the Atlantic. Moreover, huemul anatomy is adapted to open unforested habitats, also corroborated by spotless fawns. Extreme naivety towards humans resulted in early extirpation on many winter ranges—preferentially occupied by humans, resulting in refugee huemul on surrounding mountain summer ranges. Radio-marked huemul remained in small ranges with minimal altitudinal movements, as known from other subpopulations. However, these resident areas documented here are typical summer ranges as evidenced by past migrations, and current usage for livestock. The huemul is the only cervid known to use mountain summer ranges year-round in reaction to anthropogenic activities. Losing migratory traditions is a major threat, and may explain their presently prevalent skeletal diseases, reduced longevity, and lacking recolonizations for most remaining huemul subpopulations.

Stage-dependent niche segregation: insights from a multi-dimensional approach of two sympatric sibling seabirds

Niche theory predicts that to reduce competition for the same resource, sympatric ecologically similar species should exploit divergent niches and segregate in one or more dimensions. Seasonal variations in environmental conditions and energy requirements can influence the mechanisms and the degree of niche segregation. However, studies have overlooked the multi-dimensional aspect of niche segregation over the whole annual cycle, and key facets of species co-existence still remain ambiguous. The present study provides insights into the niche use and partitioning of two morphologically and ecologically similar seabirds, the common (CDP, Pelecanoides urinatrix) and the South Georgian diving petrel (SGDP, Pelecanoides georgicus). Using phenology, at-sea distribution, diving behavior and isotopic data (during the incubation, chick-rearing and non-breeding periods), we show that the degree of partitioning was highly stage-dependent. During the breeding season, the greater niche segregation during chick-rearing than incubation supported the hypothesis that resource partitioning increases during energetically demanding periods. During the post breeding period, while species-specific latitudinal differences were expected (species specific water mass preference), CDP and SGDP also migrated in divergent directions. This segregation in migration area may not be only a response to the selective pressure arising from competition avoidance between sympatric species, but instead, could reflect past evolutionary divergence. Such stage-dependent and context-dependent niche segregation demonstrates the importance of integrative approaches combining techniques from different fields, throughout the entire annual cycle, to better understand the co-existence of ecologically similar species. This is particularly relevant in order to fully understand the short and long-term effects of ongoing environmental changes on species distributions and communities.This work demonstrates the need of integrative multi-dimensional approaches combining concepts and techniques from different fields to understand the mechanism and causal factors of niche segregation.

Ecomorphology of the cervid calcaneus as a proxy for paleoenvironmental reconstruction

This study presents new ecomorphological models for the cervid calcaneus that can be used to make predictions about the nature of ancient environments. Using geometric morphometrics to quantitatively assess the length of the articular surface supporting the malleolus, the length and orientation of the tuber calcanei, and the position of the articular facets, we aimed to establish correlations between morphological traits, locomotor behavior, and environmental parameters in extant cervids. The morphology of the calcaneus was found to primarily vary with locomotor strategy and habitat, along a continuum from habitats with an open vegetation structure to habitats with a closed vegetation structure. Confounding factors, including sexual dimorphism, allometry, and phylogeny were accounted for using Principal Component Analysis, regressions and phylogenetic comparative methods. The results of our analyses suggested that these factors did not substantially obscure habitat predictions. As such, the calcaneus provides a valuable proxy for paleoenvironmental reconstruction that is broadly applicable to Quaternary fossil assemblages with a sufficiently large sample of cervids.

Importance of the morphological plasticity of Cervus elaphus in the biochronology of the Middle and Late Pleistocene of the Italian peninsula

The species Cervus elaphus is characterised by its significant and very swift ability to adapt to the broad woodland-related range of environments in the northern hemisphere, as can be seen by the large number of distinct populations and living subspecies. From studies on the phenotypic plasticity and adaptative capability of living populations of red deer, we can hypothesise that environmental conditions influenced the spread and the evolution of the species, especially in changing landscapes like those of the Italian peninsula during the Middle and Late Pleistocene. In fact, Cervus elaphus occurs on the Italian peninsula from the Middle Pleistocene, a period characterised by a particularly wide variety of environments determined by changeable palaeoclimatic and palaeogeographical conditions that are in all cases more significant in the late Middle Pleistocene and in the Late Pleistocene. If we observe the various fossil subspecies and apply the principle that present features like phenotypic plasticity are important keys to understanding the past, we must reconsider the Pleistocene red deer in evolutionary and taxonomic terms. This reappraisal also provides new data on the biochronological importance of the various red deer subspecies widespread in Italy during the Middle and Late Pleistocene.

Functional limb anatomy in a refugee species: The endangered Patagonian huemul deer (Hippocamelus bisulcus)

Early naturalists already considered huemul rare, refuged and a stocky, short-legged mountain deer, 163 years before declared endangered (1972). Anatomically, huemul do not overlap with rock-climbers previously considered analogous, as corroborated in this paper by including additional huemul cases. Assertions that population declines are caused principally via livestock infections remain unfounded. Instead, osteopathology in multiple populations across 1,000 km, affecting 57% among dead and 86% among live specimens, may relate to micronutrient deficiencies. Historically classified a mountain deer, widespread osteopathology, micronutrient deficiencies and lack of recovery qualify huemul as a refugee species. Recovery strategies thus must include repopulating historical distribution sites.

Evolution of ungulate mating systems: Integrating social and environmental factors

Ungulates exhibit diverse mating systems that range from monogamous pair territories to highly polygynous leks. We review mating systems and behaviors across ungulates and offer a new approach synthesizing how interacting factors may shape those mating systems. Variability exists in mating systems among and within species of ungulates and likely is affected by predation risk, availability of resources (food and mates), habitat structure, and sociality. Ungulate mating systems may be labile as a consequence of the varying strength of those interacting factors. In addition, degree of polygyny and sexual dimorphism in size are associated with the evolution of mating systems. Neither male-male combat nor paternal care, however, can completely explain differences in sexual size dimorphism for ungulates, a necessary component in understanding the development of some mating systems. Whatever the evolutionary pathway, sexual segregation limits paternal care allowing more intense male-male competition. Selection of habitat structure, because it modifies risk of predation, is a major determinant of sociality for ungulates. Likewise, ruggedness and steepness of terrain limit the types of mating systems that can occur because of limitations in group size and cohesiveness, as well as the ability of males to herd even small groups of females effectively. The quality and defensibility of resources affect mating systems, as does the defensibility of females. Population density of females also may be a critical determinant of the types of mating systems that develop. Size of groups likewise constrains the types of mating tactics that males can employ. Our aim was to use those relationships to create a broad conceptual model that predicts how various environmental and social factors interact to structure mating systems in ungulates. This model provides a useful framework for future tests of the roles of both ecological and social conditions in influencing the social systems of ungulates.

Ecology of a widespread large omnivore, Homo sapiens, and its impacts on ecosystem processes

Discussions of defaunation and taxon substitution have concentrated on megafaunal herbivores and carnivores, but mainly overlooked the particular ecological importance of megafaunal omnivores. In particular, the Homo spp. have been almost completely ignored in this context, despite the extinction of all but one hominin species present since the Plio-Pleistocene. Large omnivores have a particular set of ecological functions reflecting their foraging flexibility and the varied disturbances they create, functions that may maintain ecosystem stability and resilience. Here, we put the ecology of Homo sapiens in the context of comparative interspecific ecological roles and impacts, focusing on the large omnivore guild, as well as comparative intraspecific variation, focusing on hunter-gatherers.We provide an overview of the functional traits of H. sapiens, which can be used to spontaneously provide the functions for currently ecologically extinct or endangered ecosystem processes. We consider the negative impacts of variations in H. sapiens phenotypic strategies, its possible status as an invasive species, and the potential to take advantage of its learning capacities to decouple negative and positive impacts.We provide examples of how practices related to foraging, transhumance, and hunting could contribute to rewilding-inspired programs either drawing on hunter-gatherer baselines of H. sapiens, or as proxies for extinct or threatened large omnivores. We propose that a greater focus on intraspecific ecological variation and interspecific comparative ecology of H. sapiens can provide new avenues for conservation and ecological research.

Evaluating the individuality of animal-habitat relationships

Examining the ways in which animals use habitat and select resources to satisfy their life history requirements has important implications for ecology, evolution, and conservation. The advent of radio-tracking in the mid-20th century greatly expanded the scope of animal-habitat modeling. Thereafter, it became common practice to aggregate telemetry data collected on a number of tagged individuals and fit one model describing resource selection at the population level. This convention, however, runs the risk of masking important individuality in the nature of associations between animals and their environment. Here, we investigated the importance of individual variation in animal-habitat relationships via the study of a highly gregarious species. We modeled elk (Cervus elaphus) location data, collected from Global Positioning System (GPS) collars, using Bayesian discrete choice resource selection function (RSF) models. Using a high-performance computing cluster, we batch-processed these models at the level of each individual elk (n = 88) and evaluated the output with respect to: (a) the composition of parameters in the most supported models, (b) the estimates of the parameters featured in the global models, and (c) spatial maps of the predicted relative probabilities of use. We detected considerable individual variation across all three metrics. For instance, the most supported models varied with respect to parameter composition with a range of seven to 17 and an average of 14.4 parameters per individual elk. The estimates of the parameters featured in the global models also varied greatly across individual elk with little conformity detected across age or sex classes. Finally, spatial mapping illustrated stark differences in the predicted relative probabilities of use across individual elk. Our analysis identifies that animal-habitat relationships, even among the most gregarious of species, can be highly variable. We discuss the implications of our results for ecology and present some guiding principles for the development of RSF models at the individual-animal level.

Foraging ecology of Eurasian lynx populations in southwest Asia: Conservation implications for a diet specialist

Intraspecific variation in key traits of widespread species can be hard to predict, if populations have been very little studied in most of the distribution range. Asian populations of the Eurasian lynx (Lynx lynx), one of the most widespread felids worldwide, are such a case in point. We investigated the diet of Eurasian lynx from feces collected Mediterranean, mixed forest-steppe, and subalpine ecosystems of Turkey. We studied prey preferences and functional responses using prey densities obtained from Random Encounter Modelling. Our analysis revealed that the main prey was brown hare (Lepus europaeus) in all three areas (78%-99% of biomass consumed) and lynx showed a strong preference for brown hare (Chesson's selectivity index, α = 0.90-0.99). Cannibalism contributed at least 5% in two study areas. The type II functional response of lynx populations in Turkey was similar to the Canada lynx (Lynx canadensis) and daily food intake in grams per lynx matched that of Canada lynx and Iberian lynx (Lynx pardinus), both lagomorph specialists, rather than those of Eurasian lynx from Europe. Therefore, lynx in Turkey may be better described as a lagomorph specialist even though it coexists with ungulate prey. We suggest that ungulate-based foraging ecology of Eurasian lynx in Europe may be a recent adjustment to the availability of high densities of ungulates and cannot be representative for other regions like Turkey. The status of lagomorphs should become an essential component of conservation activities targeted at Eurasian lynx or when using this species as a flagship species for landscape preservation.

Daily, seasonal, and annual variations in individual home-range overlap of two sympatric species of deer

Behavioural tactics of animals are determined by both environmental and social factors. Among nonmigratory ungulates, most home-range studies focused either on the effect of environmental variables on home-range size or on the overlap between home ranges of different individuals. Here, as rarely in previous studies, we aim to identify the dynamics of the home range of a given individual, involving variation in home-range size and home-range overlap between periods, for two resident populations of contrasting species: red deer (Cervus elaphus L., 1758) and roe deer (Capreolus capreolus (L., 1758)). In both species, yearly and seasonal home-range fidelity was high and constant (mean of 64% in red deer and mean of 66% in roe deer), possibly because of benefits accruing from knowledge of spatial distribution of food resources and refugia. Home range in winter, when food availability was low, was larger than other seasonal home ranges for both species. Differences in body size between red deer and roe deer accounted for observed between-species differences in space use, especially when the species were active at night. Our study clearly demonstrates that patterns of variation in home-range size are similar; however, between-species differences in body size lead to differential patterns of home-range size and fidelity.

Demographic characterization and social patterns of the Neotropical pampas deer

The most endangered subspecies of pampas deer Ozotoceros bezoarticus uruguayensis is an endemic cervidae of the Uruguayan temperate grasslands. The aim of our study was to assess the demographic trends, grouping structure and dynamic of this small and isolated population. We surveyed the population during seven years and detected an average of 117 (+ 72.7 SD) individuals (44 censuses). The average population structure observed was 55% adult females, 34% adult males, 10% juveniles, and 1% fawns, with a low recruitment rate of 0.11. The pampas deer is a gregarious cervidae with 62% of individuals being observed within groups of at least three animals. Nevertheless we observed substantial differences on group size and composition based on sex, reproductive status, season and trophic resources availability. The population dynamics showed significant changes around the year in the sexual aggregation-segregation pattern, corresponding with reproductive and physiological status. The mean density on this population (11 deer/ km²) is the highest reported for the species. Comparable data, from other populations, showed a significant correlation between density and sex ratio, with a reduction in the proportion of males with higher deer densities. An action plan for this endangered population should include initiatives involving private landowners, and guidelines to improve the deer habitat.

Variation in reproduction of a temperate deer, the southern pudu (Pudu puda)

Pudu (Pudu puda), occurring in the southern cone of Latin America, has been classified as vulnerable by the International Union for Conservation of Nature (IUCN), yet little is known about this animal in the wild, with most knowledge on the breeding behaviour coming from captive animals. For this second-smallest deer in the world, delayed implantation has been suggested to explain the two peaks in the annual cycle of male sexual hormones on the basis of the accepted tenet that the breeding period occurs only once a year, between March and June. However, in the present study, birth dates from fawns born at the Los Canelos semi-captive breeding centre in Chile and male courting behaviour revealed the possibility of two rutting periods: autumn and spring. To our knowledge, this is the first time that late-fall births (May through early June for 17% of fawns in the study population) have been recorded for the southern pudu; two of these four births were conceived by females in the wild. From zoo and captive-animal birth records (n = 97), only three fawns were born in the fall. For all births combined (n = 121), 77% occurred in spring. The roe deer (Capreolus capreolus) and Pere David deer (Elaphurus davidianus) have been considered the only two temperate cervids in which sexual activity is initiated by increasing daylength and which breed in early summer. Yet, the present results indicate a similar response from the southern pudu when under a wild or semi-captive environment, with breeding taking place in spring. These results suggest that this species may either have two reproductive periods per year or retains the capacity to be a breeder for a much more extended period of time than documented by earlier studies. Pudu, like other temperate deer, is responsive to photoperiod for timing its breeding period, but may further optimise its production of offspring by also responding to other environmental cues such as seasonal variation in food supply when climatic conditions are favourable.

Comparison of vocalisations of introduced European red deer stags (Cervus elaphus) in north-western Patagonia (Argentina) with native European populations

Polygynous deer are very vocal species, producing calls in various contexts. Male rutting calls in red deer (Cervus elaphus) have been most studied in captive and/or free-ranging European populations. The recent application of ‘source-filter theory’ has identified the independent roles of fundamental frequency (F0) and formants in the production of deer calls and demonstrated the relation between formant spacing and anatomical characteristics such as body size. The present paper describes and characterises the acoustical properties of male rutting vocalisations for a free-ranging red deer population located in the ecotone of the eastern Andean cordillera within the Nahuel Huapi National Reserve (Neuquén, Argentina), and is the first acoustic study of free-ranging red deer stags outside their historic distribution. Recordings were made of seven identified and several unidentified stags at the peak of the rut in 2007. Calculated F0 was found to be higher for these identified stags than for Scottish red deer on the island of Rhum. The analysis of formant spacing was used to calculate the length of the vocal tract (VTL) for the seven males studied; values were comparable to those found in stags from Rhum. The longest calculated VTLs within these males corresponded to those of the four stags with the largest antler racks and the only stags holding harems. Previous studies have shown that VTL correlates with body size, age and reproductive success and that these deer have the ability to lower their larynx and extend their vocal tracts to a maximum, which is probably under sexual selection. Our data fit with this explanation. The higher F0s recorded in this population may result from the influence of wapiti genes, known to be present in these deer, because wapiti have a much higher-frequency rutting call, namely, the bugle. Alternatively, they may be related to the mating strategy, which differs substantially from the northern European populations.

Huemul heresies: beliefs in search of supporting data. 2. Biological and ecological considerations

Scarce information from remnant huemul (Hippocamelus bisulcus) populations in marginal habitats can lead to erroneous interpretations of the species’ natural history, such as assumptions of being a highly inflexible species. We evaluated discrepancies between historical accounts and recent interpretations regarding biological and ecological traits to better understand factors preventing recovery of highly endangered huemul. Early information supports the theory that huemul are currently living under suboptimal conditions. We find variability to be the norm for huemul, as with other cervids, in regard to antler characteristics, group size and density, sexual segregation, and social and feeding behaviours. No evidence supports competition and disease from livestock or red deer as having caused declines or preventing recovery. Instead, livestock management, particularly presence of people and dogs, creates incompatibilities. Where red deer are sympatric with huemul, red deer are outnumbered by livestock by 2100%, and being regularly inspected at slaughter, livestock provide a good proxy for diseases afflicting red deer. Inadequate antipredator responses due to evolutionary absence of cursorial predators are unsupported as several Canis species coexisted with huemul, overlapping with dogs that arrived with Paleoindians. Three populations have increased despite high predator density. Age at maturity for huemul is 1 year, with evidence that fawns may also breed. Reported twinning needs confirmation, but occurs in congeneric taruca (H. antisensis) and other Odocoilines, and huemul frequently raise fawns successfully every year; life cycle calculations should apply these parameters. Like taruca, dominance group breeding systems have been described repeatedly. Although huemul bucks were recently claimed unique by displaying territoriality year-round, data do not support such behaviour. Two sole dispersal records (8 and 15.5 km) are unlikely to represent maximum dispersal capacity and do not support barriers assumed from few kilometres of unsuitable habitat. Huemul using 500 ha could predictably disperse up to 90 km, well within the ranges of other cervids. Mistakenly assuming barriers and underestimating reproductive capacity may distract from discovering the factors affecting recolonisations. Sustained recovery may depend on re-establishing source populations on more productive habitats, guided by zooarcheological and historical data.

Huemul heresies: beliefs in search of supporting data. 1. Historical and zooarcheological considerations

Patagonian huemul (Hippocamelus bisulcus) was eliminated from many former ranges before arrival of early explorers who already acknowledged its rareness. Considering huemul analogous to ungulates in mountains back home, huemul was called mountain deer, which is repeatedly cited without validation and remains the orthodox interpretation. Yet other species considered analogous also use lowlands, flatlands, deserts and grasslands, and the only congeneric, H. antisensis, uses habitat with high affinity to Patagonian grasslands. Recent comparative analyses of the post-cranial morphology show that huemul cannot be associated with rock-climbing species, but falls within ranges of other cervids. Interpretations of past human utilisation rely on one study of economic anatomy and bone remains, frequently concluding that huemul was unimportant to hunter-gatherers. However, considering only bone fat and omitting easily removable fat is erroneous. Total energy of deer in autumn–winter partitions into 53% as fat and hunter-gatherers elsewhere focussed on deer during the peak fat cycle, using all easily removable fat (>1200% more energy than in bones) and consuming fat and marrow while butchering. Natives are likely to have influenced huemul distribution and density in winter ranges due to high incentives (fat) and easiness to kill. Sparse evidence is likely the result of surveys in Patagonia having been biased towards caves, leaving out transient movements and camps. Generalist cervids passed the Panama land-bridge filter to reach South America. Considering paleoclimate, Hippocamelus dispersed east of the Andes, pushed by glaciations even to north-eastern Brazil. Hippocamelus would reach and cross Andes only after deglaciations. As a mixed feeder, huemul utilised Patagonian steppe. Hunter-gatherers arrived after the last glaciation and influenced the local distribution of Hippocamelus, especially in northern and central Chile, after early adoption of an agricultural lifestyle. Introduction of horses converted native economies through adoption of an equestrian lifestyle and arrival of millions of introduced livestock, which thus affected early writings. Only few records indicate the presence of large groups of huemul far from forests, and substantial killings. Human-caused range contractions of northern ungulates affected mainly losses at low elevations and most species persisted in the marginal periphery, including high-elevation refuges. Paleoecology, zoogeography and land-use history in southern South America indicate that mountain huemul is a secondary relict created by impacts of post-Columbian colonisation. We caution against the rigid application of modern huemul habitats in interpreting past habitat use and huemul ecology, and simply considering the few extra-Andean accounts as abnormal outliers.

Seasonal and specific diet variations in sympatric red and fallow deer of southern Spain: a preliminary approach to feeding behaviour

We studied the diet composition and diet overlap in sympatric red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) throughout a whole year in order to determine variation due to season, species, sex and age class by analysing rumen contents samples of 81 red and 69 fallow deer shot monthly during 2008–09 in Sierra de Andújar Natural Park, southern Spain. We assessed diet similarity and possible inter- and intra-specific foraging competition. We found different foraging strategies for both species and sexes during constraint periods, and several theoretical considerations of specific interactions and behaviour are discussed with respect to the Mediterranean environment. In both species an annual diet dominated by grasses was recorded, peaking in spring. Browses were an important food resource at the end of winter and at the end of summer, and fruit more in autumn and winter. Red deer ingested a higher proportion of browse than fallow deer, which consumed more acorns and for a longer time showed a better ability to compensate for nutritional constraint periods. An overall decline in diet similarity in summer and at the end of winter led us to assume that exploitative competition between red and fallow deer and even between sexes was probable. Red deer females showed low diet similarity to other deer, while there was a great diet overlap between red deer males and fallow deer females at the end of summer. Differences detected between both two species and sexes do not always support predictions deriving from specific body size and morpho-physiological characteristics, but can probably be explained as a consequence of different metabolic demands. The relationship between plant nutritional attributes and food selection according to reproductive or physiological status and seasonal demands for both sexes and species should be researched in order to perform a better assessment of deer feeding behaviour.