Observations of the Loon in the Cariboo Parklands, British Columbia

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Plates 4, 5 THE Cariboo Parklands is a section of the interior plateau of British Columbia noted for the number and variety of its watered areas that together comprise the most productive waterfowl nesting grounds in the province. The present paper, a contribution to the life history of the Loon, Gavia immer (Briinnich), is based on observations made in this region during the summers of 1936 to 1943, inclusive, but includes pertinent data acquired elsewhere, chiefly during earlier years. Loons arrive in the Cariboo Parklands shortly after the ice has gone from the larger lakes, which usually takes place in late April. Farther south on Okanagan Lake, at this time, it is common to see loons in flocks sometimes containing as many as 40 individuals, and such flocks have been recorded as early as April 10 and as late as May 3. Whether these represent pre-nuptial associations or gatherings of sexually immature, non-breeding birds has not been determined. No such flocks have been observed on the Cariboo lakes. The loons that arrive there first would seem to be sexually mature, since very soon after arrival they become established on the territories they will occupy during the summer. The population seeIns to be nearly stationary. The same small lakes are occupied each year by single pairs while lakes, that to all appearances afford the same facilities of nesting sites and food, are avoided. Each year, also, the larger lakes, all of which support loon populations, have approximately the same number of occupied territories. The use of certain small lakes as breeding grounds and the avoidance of others cannot be correlated with the presence or absence of as is commonly believed. Reference to the table on page 39 will make this clear. In this table, means Kamloops trout, Salmo gairdneri kamloops, or Salmonidae; other fishes means the so-called coarse and includes no species of Salmonidae nor any commercially valuable species. It will be seen that twelve loon populations totalling 53 adults occupied lakes in which trout, or trout together with fishes, was an element in the food potential; that ten populations totalling 26 adults occupied lakes in which species than trout represented