Effects of density and weather on survival of bighorn sheep lambs (Ovis canadensis)

Portier, Christine; Festa-Bianchet, Marco; Gaillard, Jean Michel; Jorgenson, Jon T.; Yoccoz, Nigel G.

doi:10.1017/s0952836998007043

Cited by 91 publications

(131 citation statements)

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“…Norwegian herding system because most of the Finnish herds receive supplementary food in winter . Furthermore, densitydependence in juvenile survival may be difficult to detect when survival is also affected by density-independent factors (Portier et al 1998).…”

Section: Discussionmentioning

confidence: 99%

Reproductive Rate and Calf Body Mass in a North-Boreal Reindeer Herd: Effects of NAO and Snow Conditions

Aikio

Kojola²

2014

Annales Zoologici Fennici

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Aikio, P. & Kojola, I. 2014: Reproductive rate and calf body mass in a north-boreal reindeer herd: effects of NAO and snow conditions. -Ann. Zool. Fennici 51: 507-514.Population demographics of northern ungulates are influenced by density and weather conditions. For caribou and reindeer (Rangifer tarandus) that dig in the snow for winter food, snow accumulation and duration of the snow layer are suggested to be influential. Indices based on large-scale alterations of atmospheric pressure such as the North Atlantic Oscillation (NAO) are connected to climate change and may predict ecological processes better than does local weather. Some empirical evidence of the effects of climate variation is available for Arctic and alpine populations but practically none for sedentary, boreal reindeer. We examined the effects of population density, winter and spring NAO, snow accumulation, and the timing of snowmelt on reproductive success (here the calf/female ratio) and on mean summer body mass of calves in a north-boreal, free-ranging herd of semi-domesticated reindeer in northeastern Finland. In this herd, day of snowmelt explained variation in the calf/female ratio and in the midsummer body mass of calves, more so than NAO, winter snow depth and population density.

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Section: Discussionmentioning

confidence: 99%

Reproductive Rate and Calf Body Mass in a North-Boreal Reindeer Herd: Effects of NAO and Snow Conditions

Aikio

Kojola²

2014

Annales Zoologici Fennici

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“…Owen-Smith 1990; Gaillard et al 1997;Portier et al 1998), but rarely on summer drought (Saether et al 1996). Moreover, few studies have analysed the influence of the timing of rainfall upon juvenile survival within a given cohort.…”

Section: Discussionmentioning

confidence: 99%

The effects of a severe drought on mouflon lamb survival

Garel

Loison

Gaillard

et al. 2004

Proc. R. Soc. Lond. B

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The mouflon population of Caroux-Espinouse, southern France, inhabits a highly seasonal area with dry summers. We monitored summer lamb survival during a severe drought in 2003, from early June to late August. The survival of 35 radio-tagged lambs over nine two-week periods was strongly affected by the timing of rainfall. Survival depended on the amount of rainfall recorded at a given 14 day period and in the previous 14-21 day period. Survival was not influenced by the exceptionally high mean daily temperature recorded during some periods. Male lamb survival (0.68) tended to be less than female survival (0.81), although not signif icantly, possibly because of a low sample size. The high lamb mortality (25.7%) recorded during a four-month period is much higher than previous estimates of f irst-year mortality (less than 10%). We recommend accounting for climatic variation in summer when studying the population dynamics of ungulates.

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“…As the resighting probability is nearly one [6], survival estimates are very accurate. The main survival selective event for lambs occurred during winter [7]. We used 21 years of data from 1988 to 1992 and 1996 to 2011, when DNA samples were collected and paternity assigned.…”

Section: Materials and Methods (A) Animals And Populationmentioning

confidence: 99%

Sexually antagonistic association between paternal phenotype and offspring viability reinforces total selection on a sexually selected trait

et al. 2014

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The evolution of conspicuous sexually selected traits, such as horns or antlers, has fascinated biologists for more than a century. Elaborate traits can only evolve if they substantially increase reproduction, because they probably incur survival costs to the bearer. Total selection on these traits, however, includes sexual selection on sires and viability selection on offspring and can be influenced by changes in each of these components. Non-random associations between paternal phenotype and offspring viability may thus affect total selection on sexually selected traits. Long-term data on wild bighorn sheep ( Ovis canadensis ) provide the first evidence in nature that association between paternal phenotype and lamb viability strengthens total selection on horn size of adult rams, a sexually selected trait. The association of paternal horn length and offspring viability was sexually antagonistic: long-horned males sired sons with high viability but daughters of low viability. These results shed new light on the evolutionary dynamics of an iconic sexually selected trait and have important implications for sustainable wildlife management.

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Effects of density and weather on survival of bighorn sheep lambs (Ovis canadensis)

Cited by 91 publications

References 0 publications

Reproductive Rate and Calf Body Mass in a North-Boreal Reindeer Herd: Effects of NAO and Snow Conditions

Reproductive Rate and Calf Body Mass in a North-Boreal Reindeer Herd: Effects of NAO and Snow Conditions

The effects of a severe drought on mouflon lamb survival

Sexually antagonistic association between paternal phenotype and offspring viability reinforces total selection on a sexually selected trait

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