The ecological consequences of climate change have been recognized in numerous species, with perhaps phenology being the most well‐documented change. Phenological changes may have negative consequences when organisms within different trophic levels respond to environmental changes at different rates, potentially leading to phenological mismatches between predators and their prey. This may be especially apparent in the Arctic, which has been affected more by climate change than other regions, resulting in earlier, warmer, and longer summers. During a 7‐year study near Utqiaġvik (formerly Barrow), Alaska, we estimated phenological mismatch in relation to food availability and chick growth in a community of Arctic‐breeding shorebirds experiencing advancement of environmental conditions (i.e., snowmelt). Our results indicate that Arctic‐breeding shorebirds have experienced increased phenological mismatch with earlier snowmelt conditions. However, the degree of phenological mismatch was not a good predictor of food availability, as weather conditions after snowmelt made invertebrate availability highly unpredictable. As a result, the food available to shorebird chicks that were 2–10 days old was highly variable among years (ranging from 6.2 to 28.8 mg trap−1 day−1 among years in eight species), and was often inadequate for average growth (only 20%–54% of Dunlin and Pectoral Sandpiper broods on average had adequate food across a 4‐year period). Although weather conditions vary among years, shorebirds that nested earlier in relation to snowmelt generally had more food available during brood rearing, and thus, greater chick growth rates. Despite the strong selective pressure to nest early, advancement of nesting is likely limited by the amount of plasticity in the start and progression of migration. Therefore, long‐term climatic changes resulting in earlier snowmelt have the potential to greatly affect shorebird populations, especially if shorebirds are unable to advance nest initiation sufficiently to keep pace with seasonal advancement of their invertebrate prey.

No abstract

1982.Vegetative structure, concealment, and success at nests of two races of spruce grouse. Can. J. Zool. 60: 670-675.Vegetative structure, concealment, and success were compared at nests of two races of spruce grouse: Canachites canadensis canace (N = 37) in New Brunswick (1976-1980) and C . c . franklinii (N = 67) in Alberta (1970)(1971)(1972)(1973)(1974)(1975). Nests of both races were similar in design and were often located near the bole of trees or near the perimeter of tree or shrub clumps. Female spruce grouse, particularly in New Brunswick, nest in an array of stand types, densities, and ages. Hens may use certain structural cues when choosing areas to nest since canopy closure, density and percent ground cover, and density of trees at nest sites were different from what was generally available. Concealment and success at nests of canace were significantly greater than atfranklinii nests. We attribute these differences partially to the absence of a uniform dense layer of dwarf shrub ground vegetation in Alberta. Nests of adults of both races were better concealed than nests of yearlings and well-concealed nests usually were successful. REDMOND, G. W., D. M. KEPPIE et P. W. HERZOG. 1982. Vegetative structure, concealment, and success at nests of two races of spruce grouse. Can. J. Zool. 60: 670-675. La composition de la vigktation, le camouflage du nid et le succks de la nidation ont Ct C compares chez deux races de tCtras des savanes, Canachites canudensis canuce (N = 37) au Nouveau-Brunswick (1976-1980) et C . c . franklinii (N = 67) en Alberta (1970)(1971)(1972)(1973)(1974)(1975). Les nids sont semblables chez les deux races et sont souvent situCs prks du tronc d'un arbre ou prks de la p6riphCrie de bosquets d'arbres ou d'arbustes. Les tetras femelles, particulikren~ent au Nouveau-Brunswick, construisent leur nid dans une variCtC de types, de densitCs et d'tiges de boisCs. La femelle utilise peut-&re certains indices lors du choix d'un site, puisque la couverture, le pourcentage et la densit6 des couvre-sol et la densite des arbres aux sites de nidation diffkrent de ce qui est gCnCralement disponible. Le camouflage du nid et le succks de la nidation sont significativement meilleurs chez C . c . canace que chez C . c . franklinii. Ces diffkrences sont probablement attribuables en partie h l'absence d'une couche uniforme et dense de vCgCtation arbustive naine en Alberta. Chez les deux races, les nids des adultes sont mieux camoufles que ceux des oiseaux de l'annCe et un bon camouflage assure ordinairement le succks de la nidation.[Traduit par le journal]

No abstract

The hehavior af female Franklin's grouse (Cantic'hile.! conndensisfronkllnii) in response to a playhack of female aggressive calls was recorded in southwe~tem Alberta during the spnng of 1474 and late winter. spring. summer, and autumn of 1975. Resident adults initially responded with aggres5ive calling during late winter and continued to tall in TespOnSE to the recording throughout bpring. Only those overwintered yearlings that were cstabiishing spring territories within their winter nngcs respontltd by calling in early May. The onset of aggressive calling hy rehiden1 yearlings coincided wlth the spring dispersal or those yearlings that were either not responding overtly or were fleeingfrom the site from which the sound waq emanating. Dispening yearl~nps unly called aggres~ivcly after spring dispersal when they had established territorie5.f he highest level of aggressive callingmcurrcd when females were evenly spaced on territories ant1 included the penal5 of rnnting and laying. Aggressive hehavior thus appears to be a manifestation of fernate territoriality with a result~ng uniform spacing during spring. It also appear5 lii be a mechanlcm for adjljusllng the densily of remales jn a local breeding population.