The Selective Importance of Heat Stress in Gull Nest Location

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology. Abstract. A brief but intense heat wave on 9 June 1979 caused catastrophic chick mortality in a population of Western Gulls on Santa Barbara Island, California, USA. Mortality ranged from 0 to 90%o in different areas of the colony. Mortality was not a function of the amount of vegetation cover available to chicks, nor did chick age or size affect the probability of mortality during the heat wave. In the absence of a heat wave, chick mortality due to heat stress is rare in this population.Microclimate analysis in 1980 showed that the area of high chick heat stress mortality in 1979 was characterized by higher ground and air temperatures and lower wind velocities than the area of low mortality. Taxidermic thin metal chick models had a higher integrated thermal load, or operative environmental temperature, in the area of previous high mortality.The persistent nesting by gulls in areas of high potential chick mortality cannot be explained by habitat shortage or by the competitive inferiority of those birds. Enhanced access to food resources may explain the persistence of one area, but not of several others. Analysis of long-term weather records for the southern Channel Islands region showed that heat waves during the breeding season are rare: of nine possible heat waves in 62 yr of data, five have occurred since 1973. The present nesting distribution of gulls on the island has probably not evolved in a regime of frequent heat waves, but rather in response to a long period of highly equable climatic conditions.

Effects of vegetation on nest microclimate and breeding performance of lesser black-backed gulls (Larus fuscus)

“…High temperature and strong wind at the nest site can stress the incubating birds and increase their energetic demands (Bartholomew and Dawson 1979;With and Webb 1993;Wiebe and Martin 1998). Heat and wind levels can also negatively influence the performance of the chicks and even cause chick mortality (Salzman 1982). We did not detect any effect of vegetation on nocturnal minimum nest temperature.…”

Shade seeking by Common Grackle (Quiscalus quiscula) nestlings at the scale of the nanoclimate

“…Solar radiation imposes significant thermal stress on young birds by exacerbating the effects of ambient temperature (e.g. Bartholomew and Dawson, 1954;Morton and Carey, 1971;Lustick et al, 1979;Tomback and Murphy, 1981;Salzman, 1982;Webb and King, 1983;Murphy, 1985). Exposure to solar radiation at even moderate temperatures can elevate body temperatures sufficiently to elicit heat stress behaviour, including panting, postural adjustments and shade-seeking.…”

How Kentish plovers, Charadrius alexandrinus , cope with heat stress during incubation

“…If the high temperatures experienced by incubating shorebirds overwhelm their thermoregulatory capabilities, placing nests in thermally stressful sites may constrain nest attendance, which may then affect nesting success (Grant 1982;Zerba and Morton 1983;Jehl and Mahoney 1987;Wiebe and Martin 1998). Indeed, very high temperatures, although infrequent, may cause massive nest failures in some groundnesting species (Salzman 1982).…”