Observations on the Breeding Biology of Wilson's Phalarope (steganopus Tricolor) in Central Alberta

SINCE the publication of Bent's "Life histories of North American shore birds" (1927), only minor references to Wilson's Phalarope have appeared in the periodical literature.Books on the avifaunas of certain states published since then have generally added only distributional information, though Roberts (1932) and Gabrielson and Jewett (1940) give glimpses of its life history and Randali's contribution (1961) on this bird does somewhat more than this.The study reported here was carried out in the Edmonton district of Alberta, Canada, in the breeding seasons of 1962 to 1964, inclusive, but includes some observations made in the spring of 1963 near Missoula, April ] H6a•, Breeding Biology o] Wilson's Phalarope 221 1967 / wing and phalaropes securing the aquatic larval forms of many of the same prey species.(Lovenskiold [1964: 208] writing of the Red Phalarope in Spitzbergen states that when breeding it often seeks the protection of Arctic Terns ISterna paradisaea], nesting in the middle of or near their breeding colonies, though he also cites circumstantial evidence that terns in one case punctured phalarope eggs.Black Tern colonies are much looser than those of the Arctic Tern so that protection, while it may well be a factor in the Common Tern-Wilson's Phalarope association noted, is probably only a minor factor in the Black Tern-phalarope association.The fact is that Black Terns nest on almost every sizeable slough in the Edmonton district, including those which phalaropes also use.To my mind this argues for common ecological factors such as food and type of cover.)The breeding habitats are shallow sloughs with a marginal vegetation of grasses and short sedges or portions of lake shore with this type of vegetation.Waters in which a belt of tall cattails or sedges leaves no open grassy margins are not used as breeding areas though the birds may appear on them during the spring migration.(Some features of the breeding colony shown later in Figure 4 may appear to contradict this, but in the "collective feeding" areas shown on this figure the water was very shallow and a number of small weed grown islets were present.)In dry years the smaller, shallow sloughs may dry out in the spring and become useless for phalaropes.Thus, in the dry summer of 1964, many breeding sites used in previous years held no phalaropes.There was, however, no noticeable reduction in the breeding population of the district, because th'ere was more breeding on the shores of larger and deeper sloughs and lakes than previously.The smaller breeding sloughs are often very close to farms and they may be near highways with heavy traffic.In the farming country the nests sites are in hay meadows or pasture, 50 to 100 yards from the water's edge, or occasionally on islets in lakes, much nearer to open water, among rough grass.The birds breed in small colonies of from two to eight pairs.OBSERVATIONS DUl•NG THE BREEDING SEASON Arrival in spring.--Randall(1961: 205), whose experience relates mainly to Alberta, gives the end of April as the time of arrival for western Canada.For the Edmonton district, however, early to mid-May is the period in which most first sightings fall.This is evident from the following first records: (from the diaries of the late W. Rowan)

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