Significance of Brooding to the Energy Demands of Alaskan Rock Ptarmigan Chicks

Theberge, John B.; West, George C.

doi:10.14430/arctic2908

Cited by 40 publications

(22 citation statements)

References 11 publications

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“…4). Young tetraonid chicks must be periodically brooded by hens during their first ten days, particularly in rainy weather (Theberge and West 1973;Erikstad and Spidsø 1982). Despite the fact that Rock Ptarmigan chicks reach homeothermy faster than chicks of other ptarmigan species (Pedersen and Steen 1979;Holder and Montgomerie 1993), they may suffer high mortality during extreme weather events (Gardarsson 1988;Scherini et al 2003;Kobayashi and Nakamura 2013).…”

Section: Discussionmentioning

confidence: 99%

No short-term effects of climate change on the breeding of Rock Ptarmigan in the French Alps and Pyrenees

Novoa

Astruc

Desmet³

et al. 2016

J Ornithol

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In the last decades, the effects of climate warming have been particularly marked in high mountain areas. High-altitude species adapted to cold temperatures are consensually held to be particularly vulnerable to climate warming. Among these species at risk, alpine birds like the Rock Ptarmigan (Lagopus muta) are expected to exhibit a strong negative response, particularly at the southern margins of their ranges in the northern hemisphere. In this study, conducted from 1998 to 2011, we investigated whether variations in the local climate affected the breeding biology of Rock Ptarmigan in the French Alps and Pyrenees. The median hatching date did not significantly advance in either massif, suggesting that Rock Ptarmigan did not breed earlier during this period. The date of snowmelt and spring temperatures influenced the onset of breeding but not consistently in both sites. In the Alps, the median hatching date was significantly correlated with the date of snowmelt, but this correlation was less clear in the Pyrenees. Unlike woodland grouse which inhabit lower elevations, the onset of breeding in Rock Ptarmigan may be related to both date of snowmelt and spring temperatures. Reproductive success varied greatly over the years and among sites. On average, the number of young per adult in the Pyrenean population was greater than that recorded in the two populations in the Alps. A significant positive trend of reproductive success over the period of 2000-2009 was detected in the Pyrenees but not in the Alps. The model that best explained annual variation in reproductive success included the additive effects of site, date of total snowmelt and rainfall after hatching. The estimates from this model showed that for all sites, reproductive success was much lower when snowmelt was late, and rainfall after hatching was high. We did not detect any altitudinal changes in locations of either breeding females or nests, suggesting that the breeding habitat of the species has not shifted upward from 1998 to 2011. To conclude, although the Rock Ptarmigan is generally considered a potential sentinel species for indicating temperature-induced changes in alpine avifauna, our study did not show a short-term effect of climate change on the breeding biology of the southern populations of this species.

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Section: Discussionmentioning

confidence: 99%

No short-term effects of climate change on the breeding of Rock Ptarmigan in the French Alps and Pyrenees

Novoa

Astruc

Desmet³

et al. 2016

J Ornithol

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“…The ptarmigan chicks hatch with an effective down plumage and are able to travel large distances even on their first day, and they have a substantial thermogenic capacity, which is based primarily on shivering in their breast muscle (Aulie and Steen, 1976). Even so, the chicks have to return to the mother for brooding when their body temperature approaches 35°C (Theberge and West, 1973); they apparently use their thermogenic capacity only to restrict their cooling rate so that the duration of their feeding excursions becomes less dependent on ambient temperature (Jørgensen and Blix, 1988).…”

Section: Precocial Youngmentioning

confidence: 99%

Adaptations to polar life in mammals and birds

Blix

2016

Journal of Experimental Biology

141

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This Review presents a broad overview of adaptations of truly Arctic and Antarctic mammals and birds to the challenges of polar life. The polar environment may be characterized by grisly cold, scarcity of food and darkness in winter, and lush conditions and continuous light in summer. Resident animals cope with these changes by behavioural, physical and physiological means. These include responses aimed at reducing exposure, such as 'balling up', huddling and shelter building; seasonal changes in insulation by fur, plumage and blubber; and circulatory adjustments aimed at preservation of core temperature, to which end the periphery and extremities are cooled to increase insulation. Newborn altricial animals have profound tolerance to hypothermia, but depend on parental care for warmth, whereas precocial mammals are well insulated and respond to cold with non-shivering thermogenesis in brown adipose tissue, and precocial birds shiver to produce heat. Most polar animals prepare themselves for shortness of food during winter by the deposition of large amounts of fat in times of plenty during autumn. These deposits are governed by a sliding set-point for body fatness throughout winter so that they last until the sun reappears in spring. Polar animals are, like most others, primarily active during the light part of the day, but when the sun never sets in summer and darkness prevails during winter, high-latitude animals become intermittently active around the clock, allowing opportunistic feeding at all times. The importance of understanding the needs of the individuals of a species to understand the responses of populations in times of climate change is emphasized.

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“…Young chicks forage by themselves, but as they are not yet homeothermic they lose body heat while foraging and must be brooded by their parents at regular intervals to be rewarmed. On the arctic tundra, where many shorebird species breed, the weather is often adverse, and this results in reduced time for the chicks to forage (Theberge and West 1973, Boggs et al 1977, Beintema and Visser 1989. The way in which food availability and ambient temperatures together affect foraging time ultimately determines the northern limits of the breeding distribution.…”

Section: Introductionmentioning

confidence: 99%

Time Budgets and Body Temperatures of American Golden-Plover Chicks in Relation to Ambient Temperature

Krijgsveld¹,

Reneerkens²,

McNett³

et al. 2003

Condor

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Abstract. We studied time budgets of precocial chicks of American Golden-Plovers (Pluvialis dominica) on the tundra near Churchill, Manitoba, Canada, to assess how time budgets are influenced by environmental and body temperatures. Foraging time per day increased with increasing ambient temperatures and levels of solar radiation, as well as with age. This increase was due to an increase in the length of foraging bouts (i.e., the period of time in between two brooding bouts). The length of brooding bouts averaged 12 min, independent of ambient conditions or age. Body temperatures were lower under colder environmental conditions and increased as the chicks grew older. Based on measurements of cooling rates of penned chicks, we determined that at the end of a foraging bout, body temperature never fell below 35.5ЊC, which is high for a precocial chick. We suggest that in Churchill, American Golden-Plover chicks are not limited in their foraging time by ambient conditions, and they can collect sufficient food in the short periods of foraging that are available to them to sustain normal growth. By minimizing foraging bout length in favor of parental brooding, chicks may increase their digestive efficiency as well as save energy that would otherwise be expended on thermoregulation and locomotion.

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Significance of Brooding to the Energy Demands of Alaskan Rock Ptarmigan Chicks

Cited by 40 publications

References 11 publications

No short-term effects of climate change on the breeding of Rock Ptarmigan in the French Alps and Pyrenees

No short-term effects of climate change on the breeding of Rock Ptarmigan in the French Alps and Pyrenees

Adaptations to polar life in mammals and birds

Time Budgets and Body Temperatures of American Golden-Plover Chicks in Relation to Ambient Temperature

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