Coyote Abundance,Sheep Predation,and Wild Prey Correlates Illuminate Mediterranean Trophic Dynamics

ABSTRACT Sheep predation by coyotes (Canis latrans) is a major problem for sheep producers in North America. Solutions are facilitated by a basic understanding of the trophic dynamic context of this problem, one that likely varies geographically in important qualitative ways. Little is known about vertebrate trophic dynamics in Mediterranean ecosystems, where prey are diverse and their biomass is strongly influenced multi-annually by variable rainfall. We used long-term data sets from north-coastal California, USA, to investigate whether wild prey fluctuations caused immediate negative effects on sheep predation via a reduction in the coyote functional response or delayed positive effects on sheep predation via a numerical response by coyote predators. Because we could not measure prey biomass directly, we used variables associated with lower trophic levels (e.g., annual plant productivity, vole abundance, rainfall) as proxies for wild prey biomass. Coyote population growth rate was positively correlated with lower-trophic-level variables of the previous year, suggesting a numerical response, and sheep (ad F + lambs) predation was positively correlated with coyote abundance in the current year. Sheep predation also was negatively correlated with lower-trophic-level variables of the current year, suggesting an immediate buffering effect of wild prey on sheep predation. Together, coyote abundance and lower-trophic-level variables explained 47% of the multi-annual variation in sheep kills. The negative pathway between lower-trophic-level variables and sheep predation was stronger than the positive pathway, possibly due to the erratic nature of multi-annual fluctuations in lower-trophic-level variables, which could prevent the numerical response from reaching its full potential. Monthly analyses revealed a type III functional response of coyotes to lambs, which is expected to enhance buffering effects of wild prey on sheep predation. Our findings suggest the dominant effect of wild prey biomass on sheep predation by coyotes in this Mediterranean-type community is as a buffer.     

Population dynamics of Norwegian red deer: density-dependence and climatic variation.

We present a model on plant-deer climate interactions developed for improving our understanding of the temporal dynamics of deer abundance and, in particular, how intrinsic (density-dependent) and extrinsic (plants, climate) factors influence these dynamics. The model was tested statistically by analysing the dynamics of five Norwegian red deer populations between 1964 and 1993. Direct and delayed density-dependence significantly influenced the development of the populations: delayed density-dependence primarily operated through female density, whereas direct density-dependence acted through both female and male densities. Furthermore, population dynamics of Norwegian red deer were significantly affected by climate (as measured by the global weather phenomenon, the North Atlantic Oscillation: NAO). Warm, snowy winters (high NAO) were associated with decreased deer abundance, whereas the delayed (two-year) effect of warm, snowy winters had a positive effect on deer abundance. Our analyses are argued to have profound implications for the general understanding of climate change and terrestrial ecosystem functioning.     

Effects of density, climate, and supplementary forage on body mass and pregnancy rates of female red deer in Spain

The influence of short- and long-term (cohort) effects of climate and density on the life-histories of ungulates in temperate regions may vary with latitude, habitat, and management practices, but the life-histories of ungulates in the Mediterranean region are less well known. This study examined the short- and long-term effects of rainfall and absolute density on hinds in two of the southernmost populations of red deer (Cervus elaphus hispanicus) in Europe. One population received supplementary forage. Unlike more northerly latitudes, where red deer hinds lose body mass in winter as a result of adverse weather, in the Spanish populations, hinds did not lose body mass. Hinds in the population that received supplementary forage were heavier and more likely to become pregnant than were the hinds in the unsupplemented population. The likelihood of pregnancy occurring was strongly influenced by hind body mass; the proportion of yearlings that became pregnant was consequently lower in the unsupplemented population than in the population that received supplementary forage. Cohort effects on hind body mass (negative for density and positive for rainfall at birth) and on the probability of pregnancy (negative for density at birth) were apparent only in the unsupplemented population, which implies that supplemental feeding may partially compensate for negative density-dependent factors during early growth, and that supplemented deer hinds may experience reduced selection pressures. These results reflect the particular seasonal variation in the abundance and quality of food in Mediterranean habitats. The delayed effects of climate and density at birth on adult hind body mass and the prevalence of pregnancy probably affects population dynamics and constitutes a mechanism by which cohort effects affect the population dynamics in Iberian red deer. The management of Iberian red deer populations should take into account cohort effects and supplemental feeding practices, which can buffer density- and climate-dependent effects and reduce natural selection pressures.     

Demographic,mechanistic and density-dependent determinants of population growth rate: a case study in an avian predator

Identifying the determinants of population growth rate is a central topic in population ecology. Three approaches (demographic, mechanistic and density-dependent) used historically to describe the determinants of population growth rate are here compared and combined for an avian predator, the barn owl (Tyto alba). The owl population remained approximately stable (r approximately 0) throughout the period from 1979 to 1991. There was no evidence of density dependence as assessed by goodness of fit to logistic population growth. The finite (lambda) and instantaneous (r) population growth rates were significantly positively related to food (field vole) availability. The demographic rates, annual adult mortality, juvenile mortality and annual fecundity were reported to be correlated with vole abundance. The best fit (R(2) = 0.82) numerical response of the owl population described a positive effect of food (field voles) and a negative additive effect of owl abundance on r. The numerical response of the barn owl population to food availability was estimated from both census and demographic data, with very similar results. Our analysis shows how the demographic and mechanistic determinants of population growth rate are linked; food availability determines demographic rates, and demographic rates determine population growth rate. The effects of food availability on population growth rate are modified by predator abundance.     

Effect of Sub-Polar Gyre, North Atlantic Oscillation and ambient temperature on size and abundance in the Icelandic Arctic fox

Animals are exposed to environmental factors that influence their life history and body size. Here we used the Arctic fox ( Vulpes lagopus ) as an indicator of the complex links between largescale environmental variables that influence both marine and tundra trophic dynamics to demonstrate how they affect the fox's body size and abundance. The Arctic fox inhabits throughout Iceland, where it preys mainly on birds. We studied the effects of the Sub-Polar Gyre (SPG), winter and summer North Atlantic Oscillation (NAO), mean annual winter and summer temperature, and geographic sector (eastern and western Iceland, which differ in their ecology) on variations in mandible size (6345 specimens) and body mass (2732 specimens) as well as abundance on the Arctic fox in Iceland. We found that (a) SPG index negatively affected male mandible length as well as body mass of both sexes. SPG was also negatively related to fox abundance. (b) Summer NAO had a negative effect on Arctic foxes, that is, cold summers were correlated with shorter mandibles and lower body mass. (c) Winter NAO had a significant negative effect (although weaker than that of summer NAO) on female mandible length, but not on body mass. (d) Summer temperature had a positive effect on female mandible length, but no effect on body mass. However, winter temperature had no effect on either the mandible or body mass. (e) Foxes in the eastern sector had shorter mandibles and were of lighter mass than those in the western sector. We suggest that climate conditions during the growth period of the young affected their final size both directly, by influencing energy metabolism for maintenance, but mainly through their effects on food availability. As far as we are aware, this is the first report that the SPG has an effect on vertebrates, let alone terrestrial ones.     

Predation has a greater impact in less productive environments: variation in roe deer, Capreolus capreolus, population density across Europe

Aim We aimed to describe the large‐scale patterns in population density of roe deer Caprelous capreolus in Europe and to determine the factors shaping variation in their abundance. Location Europe. Methods We collated data on roe deer population density from 72 localities spanning 25° latitude and 48° longitude and analysed them in relation to a range of environmental factors: vegetation productivity (approximated by the fraction of photosynthetically active radiation) and forest cover as proxies for food supply, winter severity, summer drought and presence or absence of large predators (wolf, Canis lupus, and Eurasian lynx, Lynx lynx), hunter harvest and a competitor (red deer, Cervus elaphus). Results Roe deer abundance increased with the overall productivity of vegetation cover and with lower forest cover (sparser forest cover means that a higher proportion of overall plant productivity is allocated to ground vegetation and thus is available to roe deer). The effect of large predators was relatively weak in highly productive environments and in regions with mild climate, but increased markedly in regions with low vegetation productivity and harsh winters. Other potentially limiting factors (hunting, summer drought and competition with red deer) had no significant impact on roe deer abundance. Main conclusions The analyses revealed the combined effect of bottom‐up and top‐down control on roe deer: on a biogeographical scale, population abundance of roe deer has been shaped by food‐related factors and large predators, with additive effects of the two species of predators. The results have implications for management of roe deer populations in Europe. First, an increase in roe deer abundance can be expected as environmental productivity increases due to climate change. Secondly, recovery plans for large carnivores should take environmental productivity and winter severity into account when predicting their impact on prey.     

Soil moisture mediates association between the winter North Atlantic Oscillation and summer growth in the Park Grass Experiment

Several aspects of terrestrial ecosystems are known to be associated with the North Atlantic Oscillation (NAO) through effects of the NAO on winter climate, but recently the winter NAO has also been shown to be correlated with the following summer climate, including drought. Since drought is a major factor determining grassland primary productivity, the hypothesis was tested that the winter NAO is associated with summer herbage growth through soil moisture availability, using data from the Park Grass Experiment at Rothamsted, UK between 1960 and 1999. The herbage growth rate, mean daily rainfall, mean daily potential evapotranspiration (PE) and the mean and maximum potential soil moisture deficit (PSMD) were calculated between the two annual cuts in early summer and autumn for the unlimed, unfertilized plots. Mean and maximum PSMD were more highly correlated than rainfall or PE with herbage growth rate. Regression analysis showed that the natural logarithm of the herbage growth rate approximately halved for a 250 mm increase in maximum PSMD over the range 50-485 mm. The maximum PSMD was moderately correlated with the preceding winter NAO, with a positive winter NAO index associated with greater maximum PSMD. A positive winter NAO index was also associated with low herbage growth rate, accounting for 22% of the interannual variation in the growth rate. It was concluded that the association between the winter NAO and summer herbage growth rate is mediated by the PSMD in summer.     

Lagged effects of North Atlantic Oscillation on spittlebug Philaenus spumarius (Homoptera) abundance and survival

The North Atlantic Oscillation (NAO) is a large‐scale pattern of climate variability that has been shown to have important ecological effects on a wide spectrum of taxa. Studies on terrestrial invertebrates are, however, lacking. We studied climate‐connected causes of changes in population sizes in island populations of the spittlebug Philaenus spumarius (L.) (Homoptera). Three populations living in meadows on small Baltic Sea islands were investigated during the years 1970–2005 in Tvärminne archipelago, southern Finland. A separate analysis was done on the effects of NAO and local climate variables on spittlebug survival in 1969–1978, for which survival data existed for two islands. We studied survival at two stages of the life cycle: growth rate from females to next year's instars (probably mostly related to overwintering egg survival), and survival from third instar stage to adult. The latter is connected to mortality caused by desiccation of plants and spittle masses. Higher winter NAO values were consistently associated with smaller population sizes on all three islands. Local climate variables entering the most parsimonious autoregressive models of population abundance were April and May mean temperature, May precipitation, an index of May humidity, and mean temperature of the coldest month of the previous winter. High winter NAO values had a clear negative effect on late instar survival in 1969–1978. Even May–June humidity and mean temperature of the coldest month were associated with late instar survival. The climate variables studied (including NAO) had no effect on the growth rate from females to next year's instars. NAO probably affected the populations primarily in late spring. Cold and snowy winters contribute to later snow melt and greater spring humidity in the meadows. We show that winter NAO has a considerable lagged effect on April and May temperature; even this second lagged effect contributes to differences in humidity. The lagged effect of the winter NAO to spring temperatures covers a large area in northern Europe and has been relatively stationary for 100 years at least in the Baltic area.     

Cumulative effect of the North Atlantic Oscillation on age‐class abundance of albacore (Thunnus alalunga)

The aim of this study was to look into possible relationships between climate and the inter‐annual variability of albacore (Thunnus alalunga) catch rates by age class observed during a recreational fishery tournament at the spawning grounds of S’Estanyol (Balearic Islands, Spain) in the years 2004–2009. The mean capture per unit effort (CPUE) was significantly higher when the mean of the North Atlantic Oscillation (NAO) experienced by the albacore in winter and spring of its life history (NAO_life) was negative than when the NAO_life was positive. A statistically significant negative relationship was obtained between NAO_life and the probability of a CPUE value for an age class and year being higher than the average CPUE for all the cohorts in that age class. The results suggest that local abundance of albacore in a spawning grounds could be related to environmental factors dependent on the NAO and that there may be a cohort‐age effect. It is hypothesized that factors dependent on the NAO, such as the abundance variation of small pelagic fishes as a response to the NAO variability, could have a cumulative effect over the good biological condition (fitness) of a long‐living fish predator such as the albacore.     

Regime shifts in the breeding of an Atlantic puffin population

Timing of breeding is a key factor determining the reproductive success in bird populations and known to be affected by climate fluctuations. We investigated the long‐term (1978–2002) relationship between climate and hatching date within a population of Atlantic puffin Fratercula arctica at Røst in the Norwegian Sea. The timing of puffin breeding was found to be influenced by the North Atlantic Oscillation winter index (NAO). We isolated two temporal regimes, one where NAO had a significant effect on hatching date (1978–1986 and 1995–2002) and one where these variables were independent (1987–1994). Hatching date could be modelled using, in addition to NAO, hatching date and food abundance in the preceding breeding season (possibly proxies of parental effort). The models remained significant for regime 1 but not for regime 2. NAO differed between the two regimes suggesting that the shifts were induced by climate change, possibly via its effect on the availability of prey in the preceding year. The novelty of our study is the identification of temporal regimes in the effects of climate within one population.     

中国翼手目地理分布的环境因子影响分析

利用地理信息系统提取了中国翼手目90个物种已知地理分布点的环境因子数据,并利用主成分分析和逐步回归分析研究了这些环境因子对中国翼手目动物地理分布和种数密度分布的影响程度。结果表明,按其影响程度大小,影响中国翼手目动物地理分布的连续型环境因子依次为年平均气温、大于零度日数、一月份平均气温、无霜期日数、年降雨量、年平均相对湿度、七月份平均气温、海拔高度和年日照时数,其中年日照时数和海拔高度为负影响;影响翼手目种数密度分布的决定环境因子是年降雨量,但年平均气温也有明显作用。作者认为,气候因子影响翼手目动物地理分布的机制是限制性因子的作用,主要受冬眠和活动及摄食时间长短的限制,而种数密度分布则决定于环境资源的丰富度,即主要受到由降雨量决定的食物种类多少的影响。另外,对类别环境因子的研究表明：植被类型对翼手目的种数分布没有明显影响;具有多洞穴特点的喀斯特和火山熔岩地貌具有较多的翼手目种类,但红层地貌由于分布于南方和分散分布的特点而具有最高的翼手目种数密度[动物学报51(3)：413—422,2005]。     

Resource partitioning between large herbivores in Hustai National Park, Mongolia

Re-introduced Przewalski horses in Hustai National Park, Mongolia could suffer from food competition with other herbivore species through food resource depletion. Diet composition of the Przewalski horse (Equus ferus przewalskii), red deer (Cervus elaphus) and four livestock species (sheep, goat, cattle and horse) were studied, using micro histological analysis of faecal samples in the summer of 2005 and winter of 2006 – 2007. We expected that herbivores become less selective in food choice in winter regarding to summer, resulting in a larger diet breadth, a larger similarity in diet and a larger dietary overlap in winter, potentially triggering exploitative competition by depletion of shared resources. Vegetation biomass decreased during winter, and the different herbivores species in HNP changed their diet from summer to winter. As expected diet breadth, diet similarity and dietary overlap were significantly larger in winter in comparison to summer. The existence of competition by resource depletion between the different species cannot be ruled out. Vegetation biomass was probably not a limiting factor according to the correlation between annual rainfall and herbivore species biomass, however the forage quality may be limiting, triggering competition.     

Linking climate change to population cycles of hares and lynx

The classic 10‐year population cycle of snowshoe hares (Lepus americanus, Erxleben 1777) and Canada lynx (Lynx canadensis, Kerr 1792) in the boreal forests of North America has drawn much attention from both population and community ecologists worldwide; however, the ecological mechanisms driving the 10‐year cyclic dynamic pattern are not fully revealed yet. In this study, by the use of historic fur harvest data, we constructed a series of generalized additive models to study the effects of density dependence, predation, and climate (both global climate indices of North Atlantic Oscillation index (NAO), Southern Oscillation index (SOI) and northern hemispheric temperature (NHT) and local weather data including temperature, rainfall, and snow). We identified several key pathways from global and local climate to lynx with various time lags: rainfall shows a negative, and snow shows a positive effect on lynx; NHT and NAO negatively affect lynx through their positive effect on rainfall and negative effect on snow; SOI positively affects lynx through its negative effect on rainfall. Direct or delayed density dependency effects, the prey effect of hare on lynx and a 2‐year delayed negative effect of lynx on hare (defined as asymmetric predation) were found. The simulated population dynamics is well fitted to the observed long‐term fluctuations of hare and lynx populations. Through simulation, we find density dependency and asymmetric predation, only producing damped oscillation, are necessary but not sufficient factors in causing the observed 10‐year cycles; while extrinsic climate factors are important in producing and modifying the sustained cycles. Two recent population declines of lynx (1940–1955 and after 1980) were likely caused by ongoing climate warming indirectly. Our results provide an alternative explanation to the mechanism of the 10‐year cycles, and there is a need for further investigation on links between disappearance of population cycles and global warming in hare–lynx system.     

Density of Wild Prey Modulates Lynx Kill Rates on Free-Ranging Domestic Sheep

Understanding the factors shaping the dynamics of carnivore–livestock conflicts is vital to facilitate large carnivore conservation in multi-use landscapes. We investigated how the density of their main wild prey, roe deer Capreolus capreolus, modulates individual Eurasian lynx Lynx lynx kill rates on free-ranging domestic sheep Ovis aries across a range of sheep and roe deer densities. Lynx kill rates on free-ranging domestic sheep were collected in south-eastern Norway from 1995 to 2011 along a gradient of different livestock and wild prey densities using VHF and GPS telemetry. We used zero-inflated negative binomial (ZINB) models including lynx sex, sheep density and an index of roe deer density as explanatory variables to model observed kill rates on sheep, and ranked the models based on their AICc values. The model including the effects of lynx sex and sheep density in the zero-inflation model and the effect of lynx sex and roe deer density in the negative binomial part received most support. Irrespective of sheep density and sex, we found the lowest sheep kill rates in areas with high densities of roe deer. As roe deer density decreased, males killed sheep at higher rates, and this pattern held for both high and low sheep densities. Similarly, females killed sheep at higher rates in areas with high densities of sheep and low densities of roe deer. However, when sheep densities were low females rarely killed sheep irrespective of roe deer density. Our quantification of depredation rates can be the first step towards establishing fairer compensation systems based on more accurate and area specific estimation of losses. This study demonstrates how we can use ecological theory to predict where losses of sheep will be greatest, and can be used to identify areas where mitigation measures are most likely to be needed.     

Long-term responses in arctic ungulate dynamics to changes in climatic and trophic processes

 Following predictions from climatic general circulation models, the effects of perturbations in global climate are expected to be most pronounced in the Northern Hemisphere. Elaborating on a recently developed plant–herbivore–climate model, we explore statistically how different winter climate regimes and density-dependent processes during the past century have affected population dynamics of two arctic ungulate species. Our analyses were performed on the dynamics of six muskox and six caribou populations. In muskoxen, variation in winter climate, mediated through the North Atlantic Oscillation (NAO), explained up to 24% of the variation in interannual abundance, whereas in caribou up to 16% was explained by the NAO. Muskoxen responded negatively following warm and snowy winters, whereas caribou responded negatively to dry winters. Direct and delayed density dependence was recorded in most populations and explained up to 32% and 90% of variations in abundance of muskoxen and caribou, respectively. Received: November 19, 2001 / Accepted: May 28, 2002     

Winter North Atlantic Oscillation, temperature and ischaemic heart disease mortality in three English counties

As cold weather is an ischaemic heart disease (IHD) risk factor, year-to-year variations of the level of IHD mortality may be partly determined by inter-annual variations in winter climate. This paper investigates whether there is any association between the level of IHD mortality for three English counties and the winter North Atlantic Oscillation (NAO), which exerts a fundamental control on the nature of the winter climate over Western Europe. Correlation and regression analysis was used to explore the nature of the association between IHD mortality and a climate index (CI) that represents the interaction between the NAO and temperature across England for the winters 1974–1975 to 1989–1999. Statistically significant inverse associations between the CI and the level of IHD mortality were found. Generally, high levels of winter IHD mortality are associated with a negative CI, which represents winters with a strong negative phase of the NAO and anomalously low temperatures across England. Moreover, the nature of the CI in the early stages of winter appears to exert a fundamental control on the general level of winter IHD mortality. Because winter climate is able to explain a good proportion of the inter-annual variability of winter mortality, long-lead forecasting of winter IHD mortality appears to be a possibility. The integration of climate-based health forecasts into decision support tools for advanced general winter emergency service and capacity planning could form the basis of an effective adaptive strategy for coping with the health effects of harsh winters.     

Large-scale climatic fluctuation and population dynamics of moose and white-tailed deer

1. Mech et al . (1987) documented cumulative, negative effects of previous winters' snow on rates of population increase in moose ( Alces alces ) and white-tailed deer ( Odocoileus virginianus ), but noted no effect of predation by wolves ( Canis lupus ). Those results were contested by Messier (1991), who analysed smoothed versions of the original abundance data and reported no effect of snow accumulation on population dynamics of either species, but strong effects of wolf predation and food competition.
2. McRoberts, Mech & Peterson (1995) contended that the conclusions reached by Messier (1991) were an artefact of the use of smoothed data. In a subsequent re-analysis of the smoothed data, Messier (1995) argued that the lack of an effect of snow after one year precluded the potential for a cumulative effect beyond one year.
3. We re-analysed original and smoothed data on dynamics of moose and white-tailed deer densities using the same methods as Mech et al . (1987) and Messier (1991), but we used a measure of global climatic fluctuation, the North Atlantic Oscillation (NAO) index. The NAO is the atmospheric process determining most interannual variation in snowfall and winter temperatures in northern latitudes, and its phases drive decadal trends in wintertime precipitation.
4. We observed that rates of increase of moose and white-tailed deer in both the original and smoothed data were influenced by global climatic fluctuation at 2- and 3-year lags, as well as by delayed density-dependent feedback and wolf predation.     

Diet of Eurasian lynx, Lynx lynx, in the boreal forest of southeastern Norway: the relative importance of livestock and hares at low roe deer density

The year-round food habits of lynx were studied using radio-telemetry and snow-tracking in the boreal forest of southeastern Norway. The main objectives of the study were to clarify the importance of domestic sheep and small prey species in the diet of lynx in an area with a very low density of roe deer. During the period 1995–1999, we found 193 scats and 358 kills made by lynx. Our results indicate that roe deer were the most common prey species (contributing to 83 and 34% of the biomass consumed in winter and summer, respectively), although a wide range of other species were also found, including mountain hares, tetranoids, red foxes, domestic sheep, wild reindeer, and even moose. Most of the diet was obtained by predation, although we did document several cases of scavenging. Roe deer were more important in the diet in winter than in summer, perhaps because they were easier to locate in winter as they clustered around feeding sites. In summer, domestic sheep and small prey increased in importance. Despite the very low density of roe deer in this study area, lynx seemed to still specialise on them, although domestic sheep did constitute a significant amount to their diet, especially for males and yearlings. However, the contribution of sheep to summer diet was far from that expected if their relative density was considered.     

Main determinants of rodent population fluctuations in managed Central European temperate lowland forests

Whilst studies have shown that climatic (North Atlantic Oscillation (NAO)) and biotic (acorn production) factors influence rodent populations, mechanisms driving temporal and spatial fluctuation of rodent populations are understudied. This study evaluates relationships between the influence of environmental factors (biotic and abiotic) and phenotypic characteristics across two rodent feeding guilds (granivorous and non-granivorous species) represented by four species of rodents in Central Europe. We hypothesise that the relationship between acorn density and population growth rate are indirectly affected by climatic factors (winter NAO) and that these effects differ amongst herbivorous and granivorous species. In addition, we also tested whether effects of weather and competition on individual phenotype characteristic vary amongst mast and non-mast years. Rodent populations were estimated by catching individuals in snap traps during the growing season (from March to November) over a period of 9 years at three sites. The results of the generalised linear model provide evidence that acorn production best explained the population fluctuations. We therefore conclude that the between-year population fluctuations in rodent abundance were governed by density dependence and initiated primarily by acorn mast years. Auto-regressive models also revealed direct density dependence in combination with the direct effects of mast years. Therefore, strong intraspecific competition for food is likely in years following mast years. Our results also showed that abundance of non-granivorous species is mainly influenced by local weather conditions which could regulate food quality and abundance. On the other hand, population dynamics of granivorous species are caused directly by acorn density and indirectly by climatic condition influencing acorn production.     

Disentangling demographic effects of red deer on chamois population dynamics

Investigating the impact of ecological factors on sex‐ and age‐specific vital rates is essential to understand animal population dynamics and detect the potential for interactions between sympatric species. We used block count data and autoregressive linear models to investigate variation in birth rate, kid survival, female survival, and male survival in a population of Alpine chamois Rupicapra rupicapra rupicapra monitored over 27 years within the Stelvio National Park, Central Italian Alps, as function of climatic variables, density dependence, and interspecific competition with red deer Cervus elaphus. We also used path analysis to assess the indirect effect of deer abundance on chamois growth rate mediated by each demographic parameter. Based on previous findings, we predicted that birth rate at [t] would negatively relate to red deer abundance at year [t − 1]; survival rates between [t] and [t + 1] would negatively relate to red deer abundance at year [t − 1] and to the interactive effect of winter precipitation at [t + 1] and chamois density at [t]. Our results showed that birth rate was positively related to spring–summer precipitation in the previous year, but this effect was hampered by increasing red deer abundance. Kid and female survival rates were negatively related to the combined effect of chamois abundance and winter precipitation. Male and female survival rates were negatively related to lagged red deer abundance. The path analysis supported a negative indirect effect of red deer abundance on chamois growth rate mediated by birth rate and female survival. Our results suggest that chamois population dynamics was largely explained by the synergistic effect of density dependence and winter harshness, as well as by interspecific competition with red deer, whose effects were seemingly stronger on the kid–female segment of the population.