The sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares

Michael Sheriff, Rudy Boonstra

Research output: Contribution to journalArticle

234 Citations (Scopus)

Abstract

1. Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, or reproduction. These sub-lethal predator effects have been shown to be mediated by physiological stress. We tested the hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction in individual free-ranging female snowshoe hares, Lepus americanus. We measured the cortisol concentration from each dam (using a faecal analysis enzyme immunoassay) and her reproductive output (litter size, offspring birth mass, offspring right hind foot (RHF) length) 30 h after birth. 2. In a natural monitoring study, we monitored hares during the first and second litter from the population peak (2006) to the second year of the decline (2008). We found that faecal cortisol metabolite (FCM) concentration in dams decreased 52% from the first to the second litter. From the first to the second litter, litter size increased 122%, offspring body mass increased 130%, and offspring RHF length increased 112%. Dam FCM concentrations were inversely related to litter size (r2=0.19), to offspring birth mass (r2=0.32), and to offspring RHF length (r2=0.64). 3. In an experimental manipulation, we assigned wild-caught, pregnant hares to a control and a stressed group and held them in pens. Hares in the stressed group were exposed to a dog 1â¿¿2 min every other day before parturition to simulate high predation risk. At parturition, unsuccessfulstressed dams (those that failed to give birth to live young) and stressed dams had 837% and 214%, respectively, higher FCM concentrations than control dams. Of those females that gave birth, litter size was similar between control and stressed dams. However, offspring from stressed dams were 37% lighter and 16% smaller than offspring from control dams. Increasing FCM concentration in dams caused the decline of offspring body mass (r2=0.57) and RHF (r2=0.52). 4. This is the first study in a free-ranging population of mammals to show that elevated, predatorinduced, glucocorticoid concentrations in individual dams caused a decline in their reproductive output measured both by number and quality of offspring. Thus, we provide evidence that any stressor, not just predation, which increases glucocorticoid concentrations will result in a decrease in reproductive output.
Original languageEnglish
Pages (from-to)1249-1258
Number of pages10
JournalJournal of Animal Ecology
Volume78
DOIs
Publication statusPublished - 2009
Externally publishedYes

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Lepus americanus
sublethal effect
sublethal effects
hares
cortisol
litter size
dam
predator
predators
glucocorticoids
litters (young animals)
metabolites
reproductive performance
predation
metabolite
parturition
enzyme immunoassays
litter
predation risk
body condition

Cite this

@article{b3cef55e333d47668a211b772aea8564,
title = "The sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares",
abstract = "1. Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, or reproduction. These sub-lethal predator effects have been shown to be mediated by physiological stress. We tested the hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction in individual free-ranging female snowshoe hares, Lepus americanus. We measured the cortisol concentration from each dam (using a faecal analysis enzyme immunoassay) and her reproductive output (litter size, offspring birth mass, offspring right hind foot (RHF) length) 30 h after birth. 2. In a natural monitoring study, we monitored hares during the first and second litter from the population peak (2006) to the second year of the decline (2008). We found that faecal cortisol metabolite (FCM) concentration in dams decreased 52{\%} from the first to the second litter. From the first to the second litter, litter size increased 122{\%}, offspring body mass increased 130{\%}, and offspring RHF length increased 112{\%}. Dam FCM concentrations were inversely related to litter size (r2=0.19), to offspring birth mass (r2=0.32), and to offspring RHF length (r2=0.64). 3. In an experimental manipulation, we assigned wild-caught, pregnant hares to a control and a stressed group and held them in pens. Hares in the stressed group were exposed to a dog 1{\^a}¿¿2 min every other day before parturition to simulate high predation risk. At parturition, unsuccessfulstressed dams (those that failed to give birth to live young) and stressed dams had 837{\%} and 214{\%}, respectively, higher FCM concentrations than control dams. Of those females that gave birth, litter size was similar between control and stressed dams. However, offspring from stressed dams were 37{\%} lighter and 16{\%} smaller than offspring from control dams. Increasing FCM concentration in dams caused the decline of offspring body mass (r2=0.57) and RHF (r2=0.52). 4. This is the first study in a free-ranging population of mammals to show that elevated, predatorinduced, glucocorticoid concentrations in individual dams caused a decline in their reproductive output measured both by number and quality of offspring. Thus, we provide evidence that any stressor, not just predation, which increases glucocorticoid concentrations will result in a decrease in reproductive output.",
keywords = "10-year snowshoe hare cycle, glucocorticoid metabolites, maternal effects, natural populations, predation risk.",
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language = "English",
volume = "78",
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The sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares. / Sheriff, Michael; Boonstra, Rudy.

In: Journal of Animal Ecology, Vol. 78, 2009, p. 1249-1258.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares

AU - Sheriff, Michael

AU - Boonstra, Rudy

PY - 2009

Y1 - 2009

N2 - 1. Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, or reproduction. These sub-lethal predator effects have been shown to be mediated by physiological stress. We tested the hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction in individual free-ranging female snowshoe hares, Lepus americanus. We measured the cortisol concentration from each dam (using a faecal analysis enzyme immunoassay) and her reproductive output (litter size, offspring birth mass, offspring right hind foot (RHF) length) 30 h after birth. 2. In a natural monitoring study, we monitored hares during the first and second litter from the population peak (2006) to the second year of the decline (2008). We found that faecal cortisol metabolite (FCM) concentration in dams decreased 52% from the first to the second litter. From the first to the second litter, litter size increased 122%, offspring body mass increased 130%, and offspring RHF length increased 112%. Dam FCM concentrations were inversely related to litter size (r2=0.19), to offspring birth mass (r2=0.32), and to offspring RHF length (r2=0.64). 3. In an experimental manipulation, we assigned wild-caught, pregnant hares to a control and a stressed group and held them in pens. Hares in the stressed group were exposed to a dog 1â¿¿2 min every other day before parturition to simulate high predation risk. At parturition, unsuccessfulstressed dams (those that failed to give birth to live young) and stressed dams had 837% and 214%, respectively, higher FCM concentrations than control dams. Of those females that gave birth, litter size was similar between control and stressed dams. However, offspring from stressed dams were 37% lighter and 16% smaller than offspring from control dams. Increasing FCM concentration in dams caused the decline of offspring body mass (r2=0.57) and RHF (r2=0.52). 4. This is the first study in a free-ranging population of mammals to show that elevated, predatorinduced, glucocorticoid concentrations in individual dams caused a decline in their reproductive output measured both by number and quality of offspring. Thus, we provide evidence that any stressor, not just predation, which increases glucocorticoid concentrations will result in a decrease in reproductive output.

AB - 1. Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, or reproduction. These sub-lethal predator effects have been shown to be mediated by physiological stress. We tested the hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction in individual free-ranging female snowshoe hares, Lepus americanus. We measured the cortisol concentration from each dam (using a faecal analysis enzyme immunoassay) and her reproductive output (litter size, offspring birth mass, offspring right hind foot (RHF) length) 30 h after birth. 2. In a natural monitoring study, we monitored hares during the first and second litter from the population peak (2006) to the second year of the decline (2008). We found that faecal cortisol metabolite (FCM) concentration in dams decreased 52% from the first to the second litter. From the first to the second litter, litter size increased 122%, offspring body mass increased 130%, and offspring RHF length increased 112%. Dam FCM concentrations were inversely related to litter size (r2=0.19), to offspring birth mass (r2=0.32), and to offspring RHF length (r2=0.64). 3. In an experimental manipulation, we assigned wild-caught, pregnant hares to a control and a stressed group and held them in pens. Hares in the stressed group were exposed to a dog 1â¿¿2 min every other day before parturition to simulate high predation risk. At parturition, unsuccessfulstressed dams (those that failed to give birth to live young) and stressed dams had 837% and 214%, respectively, higher FCM concentrations than control dams. Of those females that gave birth, litter size was similar between control and stressed dams. However, offspring from stressed dams were 37% lighter and 16% smaller than offspring from control dams. Increasing FCM concentration in dams caused the decline of offspring body mass (r2=0.57) and RHF (r2=0.52). 4. This is the first study in a free-ranging population of mammals to show that elevated, predatorinduced, glucocorticoid concentrations in individual dams caused a decline in their reproductive output measured both by number and quality of offspring. Thus, we provide evidence that any stressor, not just predation, which increases glucocorticoid concentrations will result in a decrease in reproductive output.

KW - 10-year snowshoe hare cycle

KW - glucocorticoid metabolites

KW - maternal effects

KW - natural populations

KW - predation risk.

U2 - 10.1111/j.1365-2656.2009.01552.x

DO - 10.1111/j.1365-2656.2009.01552.x

M3 - Article

VL - 78

SP - 1249

EP - 1258

JO - Journal of Animal Ecology

JF - Journal of Animal Ecology

SN - 0021-8790

ER -