ARCTIC Breeding Biology of Red-throated Loons in the Canadian Beaufort Sea Region

• Main Author: D. Lynne Dickson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1991
• Subjects: Arctic; Mer de Beaufort; Toker Point; Tuktoyaktuk; Tuktoyaktuk Peninsula; Yukon; Beaufort Sea
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1032.2767; http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/download/1315/1340/

plots were established with a total area of 276 k m 2 and over 200 pairs of loons on territory each breeding season. Loon densities ranged from 0.6 pairs*km-2 on the Yukon coast to 1.8 paiwkm-2 at Toker Point on the Tuktoyaktuk Peninsula. An average of 73 % of the pairs on territory nested each year. Productivity averaged 0.63 youngmesting pair-’. The median date of egg laying ranged from 19 to 24 June in four years, but was 3 July in a year when spring thaw was late. The chicks fledged a mean of 47 d after hatch (n = lo), the first clutch chicks leaving the nesting pond in late August to mid-September. In all but one year, the mortality rate was higher for eggs than chicks, with egg losses peaking in the second half of incubation. Most (82%) chick losses occurred within three weeks of hatch (n = 61). Just 13 % of the ponds were occupied in all five years of the study, while 39 % were used in only one year. At two of the study plots, ponds with pairs that successfully reared at least one chick had a greater tendency to be occupied the following year than did ponds with unsuccessful pairs. At the other three plots, reuse of ponds was independent of breeding success the previous year. Key words: red-throated loon (Cavia srellaru), breeding biology, Beaufort Sea &SUMh. On a &di6 la reproduction.du huart 1 gorge rousse dans la partie canadienne de la mer de Beaufort de 1985 1 1989. A chacune des #riodes de reproduction, on a observt plus de 200 couples de huarts territoriaux &partis dans cinq zones exp6rimentales couvrant une superficie totale de 276 k m 2. La densit6 des huarts a vari6 de 0.6 couple par k m 2 sur la c8te du Yukon 1 1.8 couple par k m 2 1 Toker Point sur la phinsule de Tuktoyaktuk. Le nombre moyen annuel de couples nicheurs territoriaux s’est 6lev6 1 73%. La productivit6 moyenne a 6t6 de 0.63 oisillon par