Invasive exotic aoudad (Ammotragus lervia) as a major threat to native Iberian ibex (Capra pyrenaica): a habitat suitability model approach

The introduction of alien species to new environments is one of the main threats to the conservation of biodiversity. One particularly problematic example is that of wild ungulates which are increasingly being established in regions outside their natural distribution range due to human hunting interests. Unfortunately, we know little of the effects these large herbivores may have on the host ecosystems. This study deals with a first comparative analysis of the habitat requirements of two ungulate species that may be facing competition for resources in the south of Europe: the native Iberian ibex (Capra pyrenaica) and the exotic aoudad (Ammotragus lervia). The aoudad is a North African caprid introduced in 1970 as a game species in south‐eastern Spain. It has adapted well, and populations have been freely expanding since then. Ecological Niche Factor Analysis is used to describe the realized niche of both species where their distribution ranges merge. Both species occupy marginal areas of rugged terrain in the region. Marginality is higher for the Iberian ibex, which also presents a higher tolerance of secondary environmental gradients than the aoudad. Highly suitable areas for each species are secondarily suitable for the other. Reclassified and cross‐tabulated habitat suitability maps showing the areas of potential spatial coexistence and differences in ecological traits between both species are provided. The results obtained do not allow inferring resource competition between these species. However, current aoudad expansion could result in it invading the favoured habitats of the ibex. Inadequate hunting policy and monitoring, and increasing climatic resemblance of the study region to the native aoudad areas, due to a strong desertification process, are facilitating a high rate of expansion. We strongly recommend to eradicate or, at least, monitor these exotic populations, and promote active conservation practices, if one wants to preserve the unique natural resources present in this European region.     

Perspectives on the Iberian wolf in Portugal: population trends and conservation threats

The Iberian wolf (Canis lupus signatus), an endemic subspecies of the Iberian Peninsula, is endangered in Portugal. Contrary to the rest of Europe, the distribution of this subspecies has been declining in Portugal throughout the twentieth century to the present day. Knowledge of the Iberian wolf in Portugal is limited and this lack of detailed scientific knowledge makes it difficult to evaluate conservation priorities. To fill this gap, we summarize existing knowledge regarding trends and potential threats and provide a perspective on Iberian wolf population trends in Portugal, identifying potential factors modulating such trends. Priorities for research and existing monitoring gaps are presented. Declines are primarily associated with a scarcity of wild prey with consequent livestock predation, and illegal persecution primarily in retaliation for predation on livestock. If these limiting causal factors continue operating, Iberian wolf survival in Portugal is jeopardized. Wolf conservation will benefit from a long-term project including public awareness, scientific research and conservation and management solutions to protect this endangered subspecies. Future research should focus on the mechanisms regulating population size, territory occupancy and interactions with prey species, both domestic and wild.     

Effectiveness of a large reserve network in protecting freshwater biodiversity: a test for the Iberian Peninsula

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Habitat management as a generalized tool to boost European rabbit Oryctolagus cuniculus populations in the Iberian Peninsula: a cost‐effectiveness analysis

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European rabbit population trends and associated factors: a review of the situation in the Iberian Peninsula

• 1 European rabbits are considered a keystone species in the Iberian Peninsula. Their populations have sharply declined over the past century, mainly due to habitat loss and the arrival of two viral diseases: myxomatosis in the 1950s and rabbit haemorrhagic disease (RHD) at the end of the 1980s. For the conservation of the Iberian Mediterranean ecosystem, it is important to determine whether rabbit populations are recovering two decades after the RHD outbreak, and to identify the factors associated with population recovery.
• 2 Here, we review the current knowledge on recent rabbit population trends in the Iberian Peninsula and the factors associated with these trends.
• 3 Although most rabbit populations are still declining in the Iberian Peninsula, a few seem to have recovered. In general, positive trends have been recorded in species‐friendly habitats characterized by non‐fragmented landscapes, interspersed patches of Mediterranean scrubland, good pastures and/or crops, soft soils that are suitable for warren construction and a Mediterranean climate with relatively high rainfall. Additionally, rabbits seem to be recovering better in areas where management practices (e.g. low hunting pressure, habitat management and predator control) are applied to increase their numbers.
• 4 From these findings, it is possible to identify five broad objectives for rabbit conservation in the Iberian Peninsula. First, it is clearly necessary to establish a long‐term programme for monitoring rabbit abundance and trends on a large scale. Second, the conservation and restoration of open Mediterranean scrubland should be a priority for stabilizing and maintaining existing healthy rabbit populations. Third, despite the lack of experimental evidence, management activities aimed at increasing the quantity and quality of both refuge and food should continue to be implemented. Fourth, legislation on the timing of the hunting season should be revisited following recommendations made by scientists. Finally, experimental approaches are required to investigate whether the control of generalist predators is a successful strategy to allow rabbit populations to recover.

     

Historical,human, and environmental drivers of genetic diversity in the red swamp crayfish (Procambarus clarkii) invading the Iberian Peninsula

1. Patterns of genetic diversity in invasive populations can be modulated by a range of factors acting at different stages of the invasion process, including the genetic composition of the source population(s), the introduction history (e.g. propagule pressure), the environmental suitability of recipient areas, and the features of secondary introductions.
2. The North American red swamp crayfish, Procambarus clarkii, is one of the most widely introduced freshwater species worldwide. It was legally introduced into Spain twice, near the city of Badajoz in 1973 and in the Guadalquivir marshes in 1974. Thereafter the species rapidly colonised almost the entire Iberian Peninsula.
3. We used seven nuclear microsatellites to describe the genetic diversity and structure of 28 locations distributed across the Iberian Peninsula and to explain the expansion process of the red swamp crayfish. Additionally, we analysed the relationship between environmental suitability and genetic diversity of the studied locations.
4. The red swamp crayfish had a clear spatial genetic structure in the Iberian Peninsula, probably determined by the two independent introduction events in the 1970s, which produced two main clusters separated spatially, one of which was dominant in Portugal and the other in Spain.
5. The human-mediated dispersal process seemed to have involved invasion hubs, hosting highly genetically diverse areas and acting as sources for subsequent introductions. Genetic diversity also tended to be higher in more suitable environments across the Iberian Peninsula .
6. Our results showed that the complex and human-mediated expansion of the red swamp crayfish in the Iberian Peninsula has involved several long- and short-distance movements and that both ecological and anthropogenic factors have shaped the genetic diversity patterns resulting from this invasion process. Early detection of potential invasion hubs may help to halt multiple short-distance translocations and thus the rapid expansion of highly prolific invasive species over non-native areas.

     

European rabbit research in the Iberian Peninsula: state of the art and future perspectives

The European rabbit (Oryctolagus cuniculus) is a high-profile prey, native from the Iberian Peninsula, the only region in the world where the two rabbit subspecies (O. cuniculus algirus and O. cuniculus cuniculus) currently co-exist in natural conditions. In this area, this important prey represents a keystone species and ecosystem engineer of Mediterranean landscapes, being also the most harvested and one of the most managed small-game species. Additionally, the species can create damage to crops in some parts of the Iberian Peninsula where it is regarded as an agricultural pest. The scientific interest towards the species is becoming increasingly apparent most likely as a repercussion of declining population trends over the last decades. The latter has been the result of the impact of habitat deterioration, viral diseases, unsustainable hunting, and predation. In this paper, I present a review of the scientific literature currently available on the European rabbit in the Iberian Peninsula. I discuss knowledge gaps and highlight priority research guidelines to suppress them, in an attempt to provide a general perspective to target research efforts more effectively. This analysis is particularly relevant due to the current vulnerability of rabbit populations in Iberia and to the recent news of cuts in scientific funding in most Mediterranean countries.     

Sharing detection heterogeneity information among species in community models of occupancy and abundance can strengthen inference

1. The estimation of abundance and distribution and factors governing patterns in these parameters is central to the field of ecology. The continued development of hierarchical models that best utilize available information to inform these processes is a key goal of quantitative ecologists. However, much remains to be learned about simultaneously modeling true abundance, presence, and trajectories of ecological communities.
2. Simultaneous modeling of the population dynamics of multiple species provides an interesting mechanism to examine patterns in community processes and, as we emphasize herein, to improve species‐specific estimates by leveraging detection information among species. Here, we demonstrate a simple but effective approach to share information about observation parameters among species in hierarchical community abundance and occupancy models, where we use shared random effects among species to account for spatiotemporal heterogeneity in detection probability.
3. We demonstrate the efficacy of our modeling approach using simulated abundance data, where we recover well our simulated parameters using N‐mixture models. Our approach substantially increases precision in estimates of abundance compared with models that do not share detection information among species. We then expand this model and apply it to repeated detection/non‐detection data collected on six species of tits (Paridae) breeding at 119 1 km² sampling sites across a P. montanus hybrid zone in northern Switzerland (2004–2020). We find strong impacts of forest cover and elevation on population persistence and colonization in all species. We also demonstrate evidence for interspecific competition on population persistence and colonization probabilities, where the presence of marsh tits reduces population persistence and colonization probability of sympatric willow tits, potentially decreasing gene flow among willow tit subspecies.
4. While conceptually simple, our results have important implications for the future modeling of population abundance, colonization, persistence, and trajectories in community frameworks. We suggest potential extensions of our modeling in this paper and discuss how leveraging data from multiple species can improve model performance and sharpen ecological inference.

     

阿尔金山自然保护区基于野牦牛、藏野驴、藏羚羊适宜栖息地的生态容量估测

阿尔金山国家级自然保护区保护了以野牦牛(Bos mutus)、藏野驴(Equus kiang)、藏羚羊(Pantholops hodgsoni)为代表的青藏高原特有野生动物及其栖息地,但是近年来野生动物数量的快速增长引发了栖息地退化的问题,科学量化阿尔金山自然保护区各类栖息地对野牦牛、藏羚羊、藏野驴的生态容量,并提出相应的野生动物管理措施,是实现保护区可持续管理的根本途径。本文应用遥感技术和地面调查相结合的方法,系统分析了保护区内野牦牛、藏野驴和藏羚羊的栖息地需求,建立了植物生物量和NDVI的关系模型,结合三类野生动物的食性分析,估测了适宜栖息地(高寒草原、高寒荒漠草原、高寒草甸、高寒荒漠)为三类野生动物提供的可食植物量,推算了适宜栖息地和整个保护区可以承载三类野生动物的生态容量。结果表明:阿尔金山自然保护区内野牦牛、藏野驴和藏羚羊的适宜栖息地面积分别为31866.07、24035.51、24035.51 km~2,三类野生动物的适宜栖息地之间相互重叠,藏野驴和藏羚羊的适宜栖息地基本相同;全保护区内,高寒草原、高寒荒漠草原、高寒荒漠和高寒草甸分别提供了3944.91×10~4、3126.32×10~4、138.19×10~4、564.49×10~4kg可食植物量;结合三类野生动物的栖息地重叠程度及食物需求量分析,得出阿尔金山保护区的最大生态容量为野牦牛7951头/a、藏野驴6907头/a、藏羚羊27094只/a;结合三类野生动物对食物资源的占有率估计,得出阿尔金山三类野生动物的生态容量变幅为野牦牛3976—7156头/a,藏野驴3454—6216头/a、藏羚羊13547—24385只/a。根据阿尔金山自然保护区各类栖息地对三类野生动物的生态容量,提出适当控制藏野驴种群数量、增加藏羚羊种群数量的建议,以促进野生动物种群数量的持续增长和栖息地的有效保护。     

Biometrical analysis reveals major differences between the two subspecies of the European rabbit

The climatic oscillations that have occurred in the last few million years have strongly affected species distribution ranges. Highly divergent genetic lineages arose, some of which correspond to recognized subspecies that currently occupy small geographical areas. Understanding the implications of the genetic differences between these subspecies is crucial for proper conservation of Evolutionarily Significant Units. We use the two European rabbit subspecies, Oryctolagus cuniculus cuniculus and O. c. algirus, in the Iberian Peninsula as a model to investigate the repercussions at the biometric level of their largely recognized genetic differentiation. To accomplish this we analysed the ear and hind foot length, and the body mass of 999 adult rabbits from 27 locations across the distribution range of both subspecies in their native range, the Iberian Peninsula. Our results show biometric differences between the two subspecies, also explained by geographical location and sex, O. c. algirus being lighter and having shorter ear and hind foot lengths. We examine these findings under an evolutionary framework, and discuss their implications for current conservation efforts. Future research should focus on the ecological implications of these biometric differences, namely potential different habitat use and anti‐predatory strategies in the species' native range.     

Wildcat population density in NE Portugal: A regional stronghold for a nationally threatened felid

Population density data on depleted and endangered wildlife species are essential to assure their effective management and, ultimately, conservation. The European wildcat is an elusive and threatened species inhabiting the Iberian Peninsula, with fragmented populations and living in low densities. We fitted spatial capture–recapture models on camera-trap data, to provide the first estimate of wildcat density for Portugal and assess the most influential drivers determining it. The study was implemented in Montesinho Natural Park (NE Portugal), where we identified nine individuals, over a total effort of 3,477 trap-nights. The mean density estimate was 0.032 ± 0.012 wildcat/km², and density tended to increase with distance to humanized areas, often linked to lower human disturbance and domestic cat presence, with forest and herbaceous vegetation cover and with European rabbit abundance. Although, this density estimate is within the range of values estimated for protected areas elsewhere in the Iberian Peninsula, our estimates are low at the European level. When put in context, our results highlight that European wildcats may be living in low population densities across the Iberian Mediterranean biogeographic region. No phenotypic domestic or hybrid cats were detected, suggesting potentially low admixture rates between the two species, although genetic sampling would be required to corroborate this assertion. We provide evidence that Montesinho Natural Park may be a suitable area to host a healthy wildcat population, and thus be an important protected area in this species' conservation context.     

Hybridisation in European ungulates: an overview of the current status,causes, and consequences

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Habitat and Harvesting Practices Influence Horn Growth of Male Ibex

Size-selective harvesting of wild ungulates can trigger a range of ecological and evolutionary consequences. It remains unclear how environmental conditions, including changes in habitat, climate, and local weather conditions, dilute or strengthen the effects of trophy hunting. We analyzed horn length measurements of 2,815 male ibex (Capra pyrenaica) that were harvested from 1995 to 2017 in Els Ports de Tortosa i Beseit National Hunting Reserve in northeastern Spain. We used linear mixed models to determine the magnitude of inter-individual horn growth variability and partial least square path models to evaluate long-term effects of environmental change, population size, and hunting strategy on horn growth. Age-specific horn length significantly decreased over the study period, and nearly a quarter (23%) of its annual variation was attributed to individual heterogeneity among males. The encroachment of pine (Pinus spp.) forests had a negative effect on annual horn growth, possibly through nutritional impoverishment. The harvesting of trophy and selective individuals (e.g., small-horned males) from the entire population increased horn growth, probably because it reduced the competition for resources and prevented breeding of these smaller males. Local weather conditions and population size did not influence horn growth. Our study demonstrates how habitat changes are altering the horn growth of male ibex. We suggest that habitat interventions, such the thinning of pine forests, can contribute to securing the sustainability of trophy hunting. Even in situations where size-selective harvesting is not causing a detectable phenotypic response, management actions leading to the expansion of preferred land cover types, such as grass-rich open areas, can have a positive effect on ungulate fitness. Forest encroachment on open meadows and heterogeneous grasslands is pervasive throughout Mediterranean ecosystems. Therefore, our management recommendations can be extended to the landscape level, which will have the potential to mitigate the side effects of habitat deterioration on the phenotypic traits of wild ibex. © 2020 The Wildlife Society.     

A potential habitat network for the Eurasian lynx Lynx lynx in Scotland

• 1 The severe and early destruction and fragmentation of woodland habitats due to human activities is thought to have been a leading factor in the extirpation from Britain of several large, forest‐dependent mammal species, such as the Eurasian lynx Lynx lynx. However, during the 20th century, Scotland in particular has experienced rapid, large‐scale reafforestation. In order to assess if this reafforestation has been sufficient to permit the potential restoration of extirpated forest mammal species with large spatial requirements, a Geographical Information System (GIS) analysis of potential habitat of one species, the Eurasian lynx, was performed for the Scottish mainland.
• 2 A rule‐based analysis, incorporating data and expert opinion from Switzerland, an environmentally similar area where lynx now occur, was used to identify patches of suitable lynx habitat in Scotland. A connectivity analysis was used to investigate whether and how these patches are connected to form larger interconnected networks of potential lynx habitat that would allow lynx to sufficiently interact with one another to form a single interbreeding population.
• 3 Scotland has over 20 000 km² of suitable lynx habitat split into two main networks of interconnected patches: the Highlands (c. 15 000 km²) and the Southern Uplands (c. 5000 km²). A further 800 km² of potential habitat, contiguous with the Southern Uplands lynx habitat network, lies across the border in England. Although connectivity between the Highlands and Southern Uplands networks is currently weak, the implementation of measures to mitigate the barrier effects of busy roads in central Scotland could facilitate the movement of lynx between the two areas.
• 4 Based on the availability of prey resources, Scotland could support around 400 adult and subadult lynx in the Highlands and around 50 in the Southern Uplands. A Scottish population of this size would be the fourth largest lynx population in Europe considering current population estimates.

     

Density-dependent habitat selection and partitioning between two sympatric ungulates

Theory on density-dependent habitat selection predicts that as population density of a species increases, use of higher quality (primary) habitat by individuals declines while use of lower quality (secondary) habitat rises. Habitat partitioning is often considered the primary mechanism for coexistence between similar species, but how this process evolves with changes in population density remains to be empirically tested for free-ranging ungulates. We used resource-selection functions to quantify density effects on landscape-scale habitat selection of two sympatric species of ungulates [moose (Alces alces) and elk (Cervus canadensis manitobensis)] in Riding Mountain National Park, Manitoba, Canada (2000–2011). The density of elk was actively reduced from 1.2 to 0.4 elk km^?2 through increased hunting effort during the period of study, while moose density decreased without additional human influence from 1.6–0.7 moose km^?2. Patterns of habitat selection during winter by both species changed in accordance to expectations from density-dependent habitat-selection theory. At low intraspecific density, moose and elk did not partition habitat, as both species selected strongly for mixed forest (primary habitat providing both food and cover), but did so in different areas segregated across an elevational gradient. As intraspecific density increased, selection for primary habitat by both species decreased, while selection for secondary, lower quality habitat such as agricultural fields (for elk) and built-up areas (for moose) increased. We show that habitat-selection strategies during winter for moose and elk, and subsequent effects on habitat partitioning, depend heavily on the position in state space (density) of both species.     

Development of resistance to sarcoptic mange in ibex

Sarcoptic mange affects mammal host species worldwide and, particularly, wild Caprinae throughout much of Eurasia. In the Iberian Peninsula, several outbreaks of sarcoptic mange in Iberian ibex (Capra pyrenaica) have been reported since the 1980s. Using data from a period of long-term monitoring and a seasonal autoregressive integrated moving average (SARIMA)-generalized autoregressive conditional heteroscedasticity (GARCH) model approach, we performed a time-series analysis of the monthly prevalence of sarcoptic mange in the Iberian ibex population in Sierra Nevada Natural Space in southern Spain. In January 2003–March 2021, we documented a significant negative trend in sarcoptic mange prevalence, albeit with some interannual peaks. These findings can only be explained if a certain level of resistance to sarcoptic mange exists in hosts that, along with other factors, could provoke this reduced prevalence. Prevalence values varied seasonally, with maximum values in spring and minimum values at the end of summer, which may be due to factors linked to climate, host behavior, and endocrine activity. Our model predicts that the prevalence of sarcoptic mange in the Iberian ibex will continue to decrease over the next 2 years. Despite the inherent challenges involved, diagnosing and monitoring of wildlife diseases are integral to obtaining reliable epidemiological data and designing appropriate management strategies.     

Late Pleistocene and Holocene chamois in Italy

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Increasing synergistic effects of habitat destruction and hunting on mammals over three decades in the Gran Chaco

Habitat destruction and overexploitation are the main threats to biodiversity and where they co-occur, their combined impact is often larger than their individual one. Yet, detailed knowledge of the spatial footprints of these threats is lacking, including where they overlap and how they change over time. These knowledge gaps are real barriers for effective conservation planning. Here, we develop a novel approach to reconstruct the individual and combined footprints of both threats over time. We combine satellite-based land-cover change maps, habitat suitability models and hunting pressure models to demonstrate our approach for the community of larger mammals (48 species > 1 kg) across the 1.1 million km² Gran Chaco region, a global deforestation hotspot covering parts of Argentina, Bolivia and Paraguay. This provides three key insights. First, we find that the footprints of habitat destruction and hunting pressure expanded considerably between 1985 and 2015, across ~40% of the entire Chaco – twice the area affected by deforestation. Second, both threats increasingly acted together within the ranges of larger mammals in the Chaco (17% increase on average, ± 20% SD, cumulative increase of co-occurring threats across 465 000 km²), suggesting large synergistic effects. Conversely, core areas of high-quality habitats declined on average by 38%. Third, we identified remaining priority areas for conservation in the northern and central Chaco, many of which are outside the protected area network. We also identify hotspots of high threat impacts in central Paraguay and northern Argentina, providing a spatial template for threat-specific conservation action. Overall, our findings suggest increasing synergistic effects between habitat destruction and hunting pressure in the Chaco, a situation likely common in many tropical deforestation frontiers. Our work highlights how threats can be traced in space and time to understand their individual and combined impact, even in situations where data are sparse.     

河北塞罕坝秋季黑琴鸡种群密度调查

2009年10月对河北塞罕坝地区的黑琴鸡(Lyrurus tetrix)秋季种群密度进行了专项集中调查。结果表明,秋季种群密度为2.20只/km2;与历史资料对比,该地区黑琴鸡种群密度呈明显下降趋势;种群分布发生了变化;繁殖基数、繁殖成功率下降和秋季猎捕是造成黑琴鸡秋季数量下降的主要因素。目前,加强管理、阻止盗猎活动是保护当地黑琴鸡种群的最有效措施。     

Focusing Conservation Efforts for the Critically Endangered Brown-headed Spider Monkey (<Emphasis Type="Italic">Ateles fusciceps</Emphasis>) Using Remote Sensing,Modeling, and Playback Survey Methods

Brown-headed spider monkeys (Ateles fusciceps), endemic to the Choco-Darien forests and lower Andean forests of NW Ecuador, are considered critically endangered. Unfortunately, scientific data regarding the actual status of populations is lacking. We combined satellite image analysis, species-specific habitat assessment, and a field survey technique using playback to focus conservation efforts for this species. First, we identified remaining forest via a LANDSAT mosaic and then applied species-specific criteria to delineate remaining forest with potential to hold populations. By combining this with the historical distribution from ecological niche modeling and predicted hunting intensity we generated a species-specific landscape map. Within our study area, forest capable of sustaining Ateles fusciceps covers 5872 km², of which 2172 km² (40%) is protected. Unprotected forest considered suitable for Ateles fusciceps extends to 3700 km² but within this only 989 km² (23%) is under low hunting pressure and likely to maintain healthy populations of Ateles fusciceps. To overcome problems of sampling at low primate density and in difficult mountain terrain we developed a field survey technique to determine presence and estimate abundance using acoustic sampling. For sites under low hunting pressure density of primates varied with altitude. Densities decreased from 7.49 individuals/km² at 332 masl to 0.9 individuals/km² at 1570 masl. Based on combining data sets in a gap analysis, we recommend conservation action focus on unprotected lowland forest to the south and west of the Cotacachi-Cayapas Ecological Reserve where hunting pressure is low and population densities of Ateles fusciceps are greatest.