Abstract
Whereas numerous studies on large carnivores have focused on analyzing spatial patterns and habitat use, the temporal dimension of their activity has been relatively little investigated, ...making this a topic of growing interest, especially in human-dominated landscapes. Relict and isolated Apennine brown bears (
Ursus arctos marsicanus
) have been living in a human-modified landscape since millennia, but no information is available on their activity patterns. By means of GPS telemetry (26,880 GPS locations collected from 18 adult Apennine brown bears) we investigated their circadian rhythms, using hourly movement rates as an index of bear activity. Based on a Bayesian modeling approach, circadian activity of Apennine brown bears was described by a bimodal curve, with peaks of activity around sunrise and sunset. We revealed seasonal effects, with bears exhibiting higher movement rates throughout the mating season, but no relevant influence of sex. In addition, bears increased their movement rate at distances < 100–500 m to roads and settlements exclusively during spring and late summer, suggesting a trade-off between foraging opportunities and risk avoidance. The absence of a marked nocturnality in Apennine brown bears suggests a relatively low degree of habitat encroachment and disturbance by humans. Yet, the occurrence of crepuscular activity patterns and the responses in proximity of anthropogenic landscape features likely indicate a coadaptation by bears to human presence through a shift in their temporal niche. Further studies should aim to unveil fitness implications of such modifications in activity patterns.
Abstract
Apennine brown bears (
Ursus arctos marsicanus
) survive in an isolated and critically endangered population, and their food habits have been studied using traditional scat analysis. To ...complement current dietary knowledge, we applied Stable Isotope Analysis (SIA) to non-invasively collected bear hairs that had been individually recognized through multilocus genotyping. We analysed carbon (δ
13
C) and nitrogen (δ
15
N) stable isotopes of hair sections and bear key foods in a Bayesian mixing models framework to reconstruct the assimilated diet on a seasonal basis and to assess gender and management status effects. In total, we analysed 34 different seasonal bear key foods and 35 hair samples belonging to 27 different bears (16 females and 11 males) collected during a population survey in 2014. Most bears showed wide δ
15
N and δ
13
C ranges and individual differences in seasonal isotopic patterns. Vegetable matter (herbs, fleshy fruits and hard mast) represented the major component of the assimilated diet across the dietary seasons, whereas vegetable crops were rarely and C4 plants (i.e., corn) never consumed. We confirmed an overall low consumption of large mammals by Apennine bears consistently between sexes, with highest values in spring followed by early summer but null in the other seasons. We also confirmed that consumption of fleshy fruits peaked in late summer, when wild predominated over cultivated fleshy fruits, even though the latter tended to be consumed in higher proportion in autumn. Male bears had higher δ
15
N values than females in spring and autumn. Our findings also hint at additional differences in the assimilated diet between sexes, with females likely consuming more herbs during spring, ants during early summer, and hard mast during fall compared to males. In addition, although effect sizes were small and credibility intervals overlapped considerably, management bears on average were 0.9‰ lower in δ
13
C and 2.9‰ higher in δ
15
N compared to non-management bears, with differences in isotopic values between the two bear categories peaking in autumn. While non-management bears consumed more herbs, wild fleshy fruits, and hard mast, management bears tended to consume higher proportions of cultivated fruits, ants, and large mammals, possibly including livestock. Although multi-year sampling and larger sample sizes are needed to support our findings, our application confirms that SIA can effectively integrate previous knowledge and be efficiently conducted using samples non-invasively collected during population surveys.
In ecologically pristine ecosystems, top-down effects of apex predators play a fundamental role in shaping trophic cascades and structuring ecosystems, but in human-modified landscapes anthropogenic ...effects may markedly alter the ecological role of predators. In particular, human-provisioned food subsidies represent a serious concern for the conservation of apex predators, even though little empirical attention has been given to this aspect in assessing conservation outcomes. To assess the extent to which anthropogenic food subsidies affected feeding ecology of a protected wolf (Canis lupus) population in a human-modified landscape, we integrated scat-analysis (n = 1141 from 4 packs; Jan 2005–Mar 2009) and winter field inspections of Global Positioning System telemetry re-locations (n = 595 clusters and 96 single locations from 5 wolves in 5 packs and 3 floaters; 2008–2011) of wolves living in a historical national park of central Italy hosting both wild prey and livestock at high densities. We revealed that livestock dominated the wolf diet (mean biomass = 63.3 ± 14.2% SD), secondarily supplemented by wild prey (36.7 ± 5.3%, mostly wild boar Sus scrofa, roe deer Capreolus capreolus, and red deer Cervus elaphus). During winter, we revealed a higher propensity of wolves to scavenge (72.5%; n = 91 feeding events) rather than killing prey, and feeding behavior was affected by prey type (i.e., domestic vs wild ungulates) as the large majority of scavenged carrions (75.8%) were livestock carcasses abandoned on the ground that died for causes different from predation. Feeding behavior of wolves was not affected by social affiliation (i.e., pack members vs solitary wolves), indicating that pack members, even if aided by cooperative hunting, were equally likely than solitary wolves to scavenge rather than killing prey; yet, 27.5% of winter feeding events involved predation, exclusively targeted to wild prey. Our findings indicate that large livestock carrion subsidies may strongly depress predatory behavior in wolves, despite the occurrence of an abundant wild prey community, and have relevant ecological, evolutionary and management implications. Reliance on human-provided livestock carrion subsidies likely alters the ecological role of wolves by reducing their top-down cascading effects on the ecosystem, and this has relevant implications for the conservation of wolves and other apex predators in national parks. Accordingly, we call for more strict regulations to govern livestock management and practices and argue that, at least in national parks, conservation goals of apex predators need to explicitly consider their ecological role.
•Wild and domestic ungulates were comparably consumed by wolves.•Scavenging by wolves was more likely on domestic compared to wild ungulates.•Scavenging predominated both in solitary wolves and pack members.•Large availability of livestock carcasses diverged wolves from predating wild prey.•Conservation of wolves in national parks needs to address their ecological role.
As wolves in Europe are expanding in range, their impact on economic activities through predation on livestock is increasing. In this context, the effectiveness of damage compensation programs is ...being debated and requires adequate assessment. With this aim, we performed a survey of wolf depredation on livestock in Italy during the years 2010 − 2014, comparing regions of historical and more recent wolf occurrence. We collected data on livestock depredations, prevalent husbandry practices and the main features of compensation schemes. We investigated the effect of several ecological and management-related variables on the extent of wolf impact. On average, 3274 (± 195.2 SD) wolf depredation events were compensated across Italy each year, comprising 7809 (± 1278.9 SD) livestock heads, and corresponding to € 1,450,814 (± € 184,762 SD) annual compensation costs. Regions recently recolonized by wolves reported lower and decreasing levels of impact compared to those with historical wolf presence. Half of all depredations occurred in 121 municipalities (9.7% of the total), which emerged as hotspots of impact and economic cost for the system. The proportion of farms with chronically recurring damage increased by 80% in the southern Apennines, where wolves never disappeared, whereas it declined by 100% in the Alps, due to effective prevention measures implemented following wolf recolonization in the mid-1990s. Long-term human-wolf coexistence does not necessarily correspond to lower damage levels and effective conflict management, casting doubts on the effectiveness and sustainability of compensation programs, if applied without reference to a context of adaptive management.
Understanding the rich social lives of animals benefits international conservation efforts
Animal culture, defined as “information or behavior—shared within a community—which is acquired from ...conspecifics through some form of social learning” (
1
), can have important consequences for the survival and reproduction of individuals, social groups, and potentially, entire populations (
1
,
2
). Yet, until recently, conservation strategies and policies have focused primarily on broad demographic responses and the preservation of genetically defined, evolutionarily significant units. A burgeoning body of evidence on cultural transmission and other aspects of sociality (
3
) is now affording critical insights into what should be conserved (going beyond the protection of genetic diversity, to consider adaptive aspects of phenotypic variation), and why specific conservation programs succeed (e.g., through facilitating the resilience of cultural diversity) while others fail (e.g., by neglecting key repositories of socially transmitted knowledge). Here, we highlight how international legal instruments, such as the Convention on the Conservation of Migratory Species of Wild Animals (CMS), can facilitate smart, targeted conservation of a wide range of taxa, by explicitly considering aspects of their sociality and cultures.
Survival and divergence in a small group Benazzo, Andrea; Trucchi, Emiliano; Cahill, James A. ...
Proceedings of the National Academy of Sciences - PNAS,
11/2017, Letnik:
114, Številka:
45
Journal Article
Recenzirano
Odprti dostop
About 100 km east of Rome, in the central Apennine Mountains, a critically endangered population of ∼50 brown bears live in complete isolation. Mating outside this population is prevented by several ...100 km of bear-free territories. We exploited this natural experiment to better understand the gene and genomic consequences of surviving at extremely small population size. We found that brown bear populations in Europe lost connectivity since Neolithic times, when farming communities expanded and forest burning was used for land clearance. In central Italy, this resulted in a 40-fold population decline. The overall genomic impact of this decline included the complete loss of variation in the mitochondrial genome and along long stretches of the nuclear genome. Several private and deleterious amino acid changes were fixed by random drift; predicted effects include energy deficit, muscle weakness, anomalies in cranial and skeletal development, and reduced aggressiveness. Despite this extreme loss of diversity, Apennine bear genomes show nonrandom peaks of high variation, possibly maintained by balancing selection, at genomic regions significantly enriched for genes associated with immune and olfactory systems. Challenging the paradigm of increased extinction risk in small populations, we suggest that random fixation of deleterious alleles (i) can be an important driver of divergence in isolation, (ii) can be tolerated when balancing selection prevents random loss of variation at important genes, and (iii) is followed by or results directly in favorable behavioral changes.
Representing a form of anthropogenic hybridization, wolf–dog interbreeding may potentially compromise the ecological and evolutionary traits of local wolf populations and corrode social tolerance ...towards wolves. However, estimates of the extent of wolf–dog hybridization in wolf populations are scarce, especially at a multi-pack scale and in human-dominated landscapes. Using non-invasive (
n
= 215) and invasive (
n
= 25) samples of wolf-like canids collected in the Province of Grosseto (central Italy, 2012–2014), we assessed the extent of wolf–dog hybridization based on multi-locus genotypes (16 and 49 loci for non-invasive and invasive samples, respectively) and Bayesian clustering techniques. Based on a total of 72 genotypes, the minimum proportion of admixed individuals in our sample was 30.6%, comprising 8 out of the 13 surveyed packs; however, by correcting for the proportion of admixed individuals undetected using the 16-loci compared with the 49-loci marker set (26.7%), we suspect the rate of recent admixture could be closer to 50%. While we did not detect any F1 hybrid, four admixed individuals had a non-negligible probability of being first-generation backcrosses, one of which likely derived from a backcross of a F1 hybrid into the dog population. Complementary genetic markers (i.e., Y-haplotype and K-locus) or anomalous morphological traits further indicated widespread occurrence of admixed individuals of older generations of backcross. This high level of admixture raises serious wolf conservation concerns and exemplifies the expected dynamics of wolf–dog hybridization if left unmanaged in human-dominated landscapes. The implications of our findings need to be urgently upscaled for the implementation of management interventions that cannot be procrastinated any longer at the regional and national scale.
The assessment of animal body condition has important practical and management implications for endangered wildlife populations. The nutritional condition of a population can be evaluated in a ...non-invasive way using photogrammetry techniques, avoiding direct manipulation. This study evaluates the utility of using body condition scoring (BCS) based on the visual assessment of subcutaneous fat and muscle from the body contour as a non-invasive method to quantify body condition in free ranging bears from camera trap photographs. Photographs of Apennine brown bears (
Ursus arctos marsicanus
), taken between 2007 and 2009 in the Abruzzo, Lazio and Molise National Park (PNALM, Italy), were used to evaluate the potential of this technique. BCS assessment was performed on 754 photographs representing 71 independent observations. Forty-eight of these photographs were selected to also score quantitative body ratios using a standardised measure of torso height. BCS varied seasonally, as expected by food availability and brown bear nutritional physiology, and it was also positively correlated to all three body ratios. Our findings indicate that BCS assessment is a good proxy for body condition, and that camera trap data can be effectively used to assess and monitor the nutritional condition of bear populations, such as the critically endangered one in central Italy.
Anthropogenic and biotic disturbances have the potential to interact, generating cumulative impacts on animal movement or, alternatively, counterbalancing or masking each other. Despite their ...importance, those interactions have not been investigated thoroughly. Our study aimed to fill this knowledge gap by assessing the combined effects of a human activity-that is, military exercises-and a biotic disturbance-that is, insect harassment-on movement rates of free-ranging semidomesticated reindeer (Rangifer tarandus tarandus). From 2010 to 2012, we analyzed location data from fifty-one Global Positioning System (GPS)-collared female reindeer in the largest European military test range, situated in northern Sweden. In the presence of both military exercises and mosquito harassment, reindeer reacted by increasing their movement rates but not as much as when mosquito harassment occurred alone. Conversely, reindeer reduced their movement rates during military exercises performed with aircraft. Moreover, the effect of military exercises performed with vehicles was evident only when combined with mosquito harassment. These results stress the value of evaluating the effects of the interaction between biotic disturbances and human activities, especially in northern ecosystems, because of the predicted climate warming and the growing interest toward natural resource extraction and other forms of land use.
The low cost and rapidity of microsatellite analysis have led to the development of several markers for many species. Because in non-invasive genetics it is recommended to genotype individuals using ...few loci, generally a subset of markers is selected. The choice of different marker panels by different research groups studying the same population can cause problems and bias in data analysis. A priority issue in conservation genetics is the comparability of data produced by different labs with different methods. Here, we compared data from previous and ongoing studies to identify a panel of microsatellite loci efficient for the long-term monitoring of Apennine brown bears (Ursus arctos marsicanus), aiming at reducing genotyping uncertainty and allowing reliable individual identifications overtimes.
We examined all microsatellite markers used up to now and identified 19 candidate loci. We evaluated the efficacy of 13 of the most commonly used loci analyzing 194 DNA samples belonging to 113 distinct bears selected from the Italian national biobank. We compared data from 4 different marker subsets on the basis of genotyping errors, allelic patterns, observed and expected heterozygosity, discriminatory powers, number of mismatching pairs, and probability of identity. The optimal marker set was selected evaluating the low molecular weight, the high discriminatory power, and the low occurrence of genotyping errors of each primer. We calibrated allele calls and verified matches among genotypes obtained in previous studies using the complete set of 13 STRs (Short Tandem Repeats), analyzing six invasive DNA samples from distinct individuals. Differences in allele-sizing between labs were consistent, showing a substantial overlap of the individual genotyping.
The proposed marker set comprises 11 Ursus specific markers with the addition of cxx20, the canid-locus less prone to genotyping errors, in order to prevent underestimation (maximizing the discriminatory power) and overestimation (minimizing the genotyping errors) of the number of Apennine brown bears. The selected markers allow saving time and costs with the amplification in multiplex of all loci thanks to the same annealing temperature. Our work optimizes the available resources by identifying a shared panel and a uniform methodology capable of improving comparisons between past and future studies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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