Seasonal changes in aggressive behavior of female spruce grouse

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.

The fall phase of dispersal in juvenile spruce grouse

“…Downloaded from www.nrcresearchpress.com by McMaster University on 12/22/14 For personal use only. aspects of behaviour, such as movements and dispersion (Herzog and Boag 1978), and timing of migration and dispersal (Herzog and Keppie 1980), and were as follows: winter, 16 October -31 March; and summer, 16 May -15 August. These designations with up to 2 months between them enabled me to avoid confusion between early and late movements, either dispersal or migration, and normal daily movements within summer or winter ranges.…”

“…Wintering areas were delineated when the median locations of three or more adult grouse occurred in a cluster in which the distance between neighbours did not exceed 80 m (mean radius of the winter range of radio-tracked adults; Herzog and Boag 1978). A perimeter was drawn around each cluster enclosing all its median locations as well as a boundary area extending 80 m from the outer medians of the cluster, thus encompassing the area used by peripherally located birds.…”

“…Keppie (1975) found that the fall emigration rate of juvenile males (41 %) was significantly lower than that of females (75%), and suggested that the higher emigration rate of females was probably related to their greater overall fall dispersal distances. Ap-art from documentation of fall movements in juvenile spruce grouse, the cause of the observed variability b,etween sexes, such as with distances moved, has been suggested to be the result of intraspecific interactions and (or) innate behavioural differences (Herzog andBoag 1977, 1978;Alway and Boag 1979;Keppie 1979Keppie , 1980. Although Keppie (1 975) observed juveniles moving with their migrating brood hens, the date of brood breakup in relation to the timing of adult female migration was not examined.…”

Spruce grouse, a non-gregarious and sparsely distributed forest bird, shows synchronous nesting

“…Hannon et al (1982) speculated that adult female blue grouse delay the time that yearlings breed by some behavioral interaction. This hypothesis seems reasonable for spruce grouse because some females are aggressive toward other females prior to nesting (Herzog and Boag 1977;Nugent and Boag 1982). Interaction among females was not measured directly in this study, and results are equivocal.…”

Surplus yearlings and the regulation of breeding density in blue grouse

“…For instance, if a certain proportion of young males, which do not normally hold territory, must become established as subsequent breeders (e.g., as standby birds) and others are excluded, this may limit the number of males in the next breeding population. As well, evidence is accumulating that some form of spacing behaviour may exist among females in polygynous tetraonids (Stirling 1968;Bendell et al 1972;Zwickel 1972Zwickel , 1973Herzog andBoag 1977, 1978;Hannon 1978). If so here is a mechanism for the possible exclusion of surplus females.…”