Dataset Information

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

ABSTRACT: 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.

SUBMITTER: Bauwens D

PROVIDER: S-EPMC6540836 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Seasonal variation of mortality, detectability, and body condition in a population of the adder (<i>Vipera berus</i>).

Bauwens Dirk D Claus Katja K

Ecology and evolution 20190415 10

We analyzed seasonal variation in mortality rates in adult males and females of the European adder (<i>Vipera berus</i>), 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 ...[more]

PMID: 31161001

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Project description:Female adders (Vipera berus) are "capital breeders" that exhibit delayed maturity and intermittent reproductive frequency. We studied the attainment of sexual maturity, the initiation of annual breeding in mature females, the energy and mortality costs associated with breeding, the length of the reproductive cycle and female lifetime reproductive frequency. We use longitudinal data obtained during an 18-year (2000-2017) mark-recapture study in a large population of adders in northern Belgium. A minority (15%) of the females gave birth to their first litter when they attained the actual age of 3 years, upon surpassing a minimum snout-vent-length of 38 cm. However, most females reproduced for the first time when they were 4 years or older. In mature females, breeding in a given year depends to a large extent on their body condition at the onset of the active season, indicating that a threshold level of energy reserves is necessary to start a reproductive cycle. During breeding years females stop growing, lose about one-third of their initial body mass and are very emaciated after parturition. The decrease in relative body mass was most notable initially in the largest and fattiest females. During the non-breeding years, females forage intensely to rebuild their fat reserves; their abilities to do so will strongly affect whether and when they engage in subsequent reproductive bouts. We used a multistate mark-recapture analytical method to simultaneously estimate the capture and survival rates of breeding and non-breeding females, a necessary procedure to obtain accurate estimates of survival probabilities. The analysis indicated much higher capture rates during the breeding years, but did not reveal a substantial effect of reproductive state on annual survival rates. Although some females were observed to breed in successive years, the reproductive cycle was most often biennial or triennial. However, most females (ca. 70%) that attained sexual maturity reproduced only once during their lifetime, while a minority of the females (ca. 5%) were observed to breed on 3-5 annual occasions. On average, females produced only ca. 1.3 litters during their reproductive lifetime. The short reproductive lifetime is a consequence not only of mortality directly related to the reproductive activities, but also of mortality associated with recovering from the weakened post-parturient body condition during the long intervals (1-2 years) between reproductive bouts.

Project description:BackgroundAcute kidney injury (AKI) is associated with high morbidity and mortality in dogs, but diagnosis may be impaired due the insensitivity of routine renal function biomarkers to detect earlier or milder forms of injury. Snake envenomation is one of several causes of AKI in dogs and humans. Dogs are commonly envenomated by the European adder (Vipera berus) between April and October each year, but few studies exist examining serial serum creatinine (sCr) and symmetric dimethylarginine (SDMA) measurements and AKI biomarkers in these dogs. Novel urinary biomarkers could improve clinical outcome by allowing earlier diagnosis of and intervention in AKI. The aim of this study was to assess the presence of AKI in dogs envenomated by V. berus at 12, 24 and 36 h after bite, as well as 14 days later, using sCr, SDMA and a panel of urinary AKI biomarkers normalised to urine creatinine (uCr), compared to a group of healthy control dogs.ResultsThirty-five envenomated dogs and 35 control dogs were included. Serum creatinine did not exceed the upper reference limit at any time point in any dog after envenomation. Serum SDMA did not exceed 0.89 μmol/L in any dog. Compared to controls, urinary albumin/uCr, neutrophil gelatinase-associated lipocalin/uCr and monocyte chemotactic protein-1/uCr were significantly elevated 12 h (P < 0.0001, P < 0.0001, P = 0.01), 24 h (P < 0.001, P < 0.001, P = 0.002) and 36 h (P < 0.001, P < 0.001, P = 0.0008) after bite. Osteopontin/uCr was higher 24 and 36 h after bite (P < 0.0001), kidney injury molecule-1/uCr, interleukin-8/uCr and γ- glutamyl transferase/uCr were significantly higher 36 h after bite (P = 0.003, P = 0.0005, P = 0.001). Urinary cystatin C/uCr was not significantly different to controls at any timepoint. Biomarker/uCr ratios were not significantly different 14 days after envenomation compared to controls.ConclusionUrinary biomarker/Cr ratios are indicative of mild transient, non-azotaemic AKI in dogs envenomated by V. berus.

Dataset Information

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

Publications

Seasonal variation of mortality, detectability, and body condition in a population of the adder (<i>Vipera berus</i>).

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