Genotyping validates photo‐identification by the head scale pattern in a large population of the European adder (<i>Vipera berus</i>)

Bauwens, Dirk; Claus, Katja; Mergeay, Joachim

doi:10.1002/ece3.3917

Cited by 22 publications

(33 citation statements)

References 26 publications

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“…Snakes were located by sight while walking slowly and erratically through the terrain, captured by hand, and released immediately after handling. A digital photograph of the upper side of the head allows individual identification of adders, on the basis of the number, shape, and arrangement of the head scales (Bauwens, Claus, & Mergeay, ). At every encounter, we also recorded date, time, exact location (GPS coordinates), sex, SVL (to the nearest 5 mm), body mass (to the nearest 1 g), and indications of recent food intake (midbody swelling, excretion of feces).…”

Section: Methodsmentioning

confidence: 99%

Seasonal variation of mortality, detectability, and body condition in a population of the adder (Vipera berus)

Bauwens

Claus

2019

Ecology and Evolution

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We analyzed seasonal variation in mortality rates in adult males and females of the European adder (Vipera berus), using data collected during a 13‐year capture–recapture study (2005–2017) in a large population. We concurrently obtained quantitative information on the seasonal variation in the detectability and body condition of adders. Our results show strong seasonality in body condition, encounter, and capture rates of adult adders, and these patterns differ markedly between sexes and between breeding and nonbreeding females. Seasonal variation in mortality rates was however virtually nonexistent in males and moderately low in both breeding and nonbreeding females. In addition, we found no evidence for among‐year differences in the seasonal mortality schedules of males and females. During periods of intensive basking, both males and pregnant females are highly visible for humans, but are not subject to strong natural mortality. This low susceptibility to predation is presumably induced by various factors, including the limitation of overt exposure to short periods of time and specific microhabitats, the dorsal coloration pattern that provides cryptic protection and possibly also an aposematic warning signal, and presumed seasonal differences in the foraging behavior and food requirements of natural predators. Our data provide some evidence that female adders, but not males, are relatively vulnerable to predation during the seasonal migrations between the hibernation and feeding habitats. Mortality in the females was not much elevated during their breeding years, but was notably highest in the spring of the ensuing nonbreeding year. After giving birth, reproductive females are extremely emaciated and have a weakened general condition. They then run the risk of dying from starvation either before, during, or after hibernation. The higher mortality after giving birth, that is sustained over a period of ca. 9 months, should be considered as an indirect and delayed survival cost of reproduction.

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Section: Methodsmentioning

confidence: 99%

Seasonal variation of mortality, detectability, and body condition in a population of the adder (Vipera berus)

Bauwens

Claus

2019

Ecology and Evolution

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“…Interpretation of results. We compared our results for F-statistics and allele richness from UKAGP study populations with summary statistics from two published studies of adder populations in mainland Europe [44,77], and from a site containing a very large (n >500) population of lowland adders in northern Belgium ( [78], Mergeay & Bauwens unpublished data). Direct statistical comparison was precluded by only partially overlapping microsatellite panels between the studies (2/8 loci of our study were in common with Ursenbacher et al [44,77]; 3/8 loci in common with Bauwens et al [78]).…”

Section: Plos Onementioning

confidence: 99%

“…Although exceeding the MTAC peak count threshold, the springtime counts for the UKAGP populations in the "large" category were still relatively low, with a maximum of 27. In the absence of a very large well-characterised UK population for comparison, we analysed 50 genotypes from the Belgian site [78], focusing primarily on indices of relatedness and inbreeding. This 1570 ha site ("Groot Schietveld", N 51˚20-22'-E 4˚32-37'), has been used as a military exercise zone since 1893, and is separated from neighbouring adder populations by a minimum of 18km of unsuitable agricultural habitat.…”

Section: Plos Onementioning

confidence: 99%

Genetic and demographic vulnerability of adder populations: Results of a genetic study in mainland Britain

Ball

Hand²,

Willman

et al. 2020

PLoS ONE

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Genetic factors are often overlooked in conservation planning, despite their importance in small isolated populations. We used mitochondrial and microsatellite markers to investigate population genetics of the adder (Vipera berus) in southern Britain, where numbers are declining. We found no evidence for loss of heterozygosity in any of the populations studied. Genetic diversity was comparable across sites, in line with published levels for mainland Europe. However, further analysis revealed a striking level of relatedness. Genetic networks constructed from inferred first degree relationships suggested a high proportion of individuals to be related at a level equivalent to that of half-siblings, with rare inferred full-sib dyads. These patterns of relatedness can be attributed to the high philopatry and low vagility of adders, which creates high local relatedness, in combination with the polyandrous breeding system in the adder, which may offset the risk of inbreeding in closed populations. We suggest that reliance on standard genetic indicators of inbreeding and diversity may underestimate demographic and genetic factors that make adder populations vulnerable to extirpation. We stress the importance of an integrated genetic and demographic approach in the conservation of adders, and other taxa of similar ecology.

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“…80% of forests are situated in Wallonia; Jacob et al, 2007); an isolated and large population persists in northern Belgium in a military zone (Bauwens, Claus & Mergeay, 2018). Remaining habitats favorable for snakes are patchy and concentrated in the south regions (e.g.…”

Section: Study Sitesmentioning

confidence: 99%

“…Remaining habitats favorable for snakes are patchy and concentrated in the south regions (e.g. 80% of forests are situated in Wallonia; Jacob et al, 2007); an isolated and large population persists in northern Belgium in a military zone (Bauwens, Claus & Mergeay, 2018). From 2000, patches of suitable habitats were intensively prospected in southern Belgium in a landscape that broadly covers 300 000 hectares (49.85°N and 50.2°N, 4.6°E and 5.3°E, humid temperate climate, 70-500 m ASL, Fig.…”

Section: Study Sitesmentioning

confidence: 99%

Catastrophic impact of wild boars: insufficient hunting pressure pushes snakes to the brink

Graitson¹,

Barbraud

Bonnet

2018

Animal Conservation

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Climatic changes, habitat loss and invasive species are important threats for many animal populations. Here, we report rapid declines and extinctions of adder populations monitored during 12 years in Belgium where none of the above causes was involved. This study provides the first large-scale data showing that wild boars represent a major risk for snakes, pushing populations to extinction. Drastic population declines were observed in the sites impacted by wild boars (N = 14), while in other sites spared by wild boars populations remained stable (N = 9). Wild boars are highly fertile and their main predators have been extirpated from Western Europe; yet, recreational hunting kept populations in check during decades. Hunting pressure is currently insufficient to control the rapid expansion of wild boars, demographic outbreaks are increasingly frequent. Wild boars are omnivorous; they can destroy snakes directly and indirectly through the depletion of snake's preys and via the destruction of key microhabitats. Snakes exhibit limited dispersal capacities; they cannot escape local perturbations and thus are highly vulnerable. Because wild boars have a very eclectic diet, are prolific breeders and are able to devastate a range of habitats their negative impact under relaxed hunting pressure applies to a huge variety of organisms, including reptiles. Policies to limit wild boar populations are urgently needed. Recommendations to target reproductive females and piglets should be generalized and applied.

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Genotyping validates photo‐identification by the head scale pattern in a large population of the European adder (Vipera berus)

Cited by 22 publications

References 26 publications

Seasonal variation of mortality, detectability, and body condition in a population of the adder (Vipera berus)

Seasonal variation of mortality, detectability, and body condition in a population of the adder (Vipera berus)

Genetic and demographic vulnerability of adder populations: Results of a genetic study in mainland Britain

Catastrophic impact of wild boars: insufficient hunting pressure pushes snakes to the brink

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