Feature Articles

Post-Spring Migration Colony-site Prospecting by Roseate Terns (Sterna dougallii)

Jeffrey A. Spendelow and Adam J. Eichenwald

We recorded banded Roseate Terns (Sterna dougallii) and unbanded individuals mated to banded individuals in May and the first third of June in 2001 and 2002 to quantify post-spring migration prospecting by this species at Falkner island, Connecticut.  In 2001, more than one quarters: 34/125 (27.2%) of those observed by 19 May and 38/150 (25.3%) of those observed by 25 May did not remain at this colony site and went elsewhere to attempt breeding.  In 2002, fewer terns were observed by 19 May, but an even higher percentage: 11/28 (39.3%) of those seen by 19 may and 58/151 (38.4%) of those seen by 25 May did not stay and nest.  Our results demonstrate that a substantial proportion of the earliest arriving individuals at this site are prospecting and gathering information about local conditions before making a decision about going elsewhere to nest.

 

Status, Condition, and Movement Patterns of Red-breasted Nutchatches in Anchorage, Alaska, 1990-1995

Michael R. North

I studied the migration, body condition, and age and sex demographics of Red-breasted Nuthatch (Sitta Canadensis) populations in Anchorage, Alaska from 1990-1995.  Red-breasted Nuthatches are a recent addition to the avifauna of much of Alaska.  Presumably, habitat change and climate change are ameliorating conditions near the northern range limits for this species.  The sampled population (n= 94) included 73.5% migrants and 20.2% winter residents and winter visitors and was dominated by males (64.9%).  Winter residents showed a high degree of site fidelity between years.  Fall migration occurred from mid-Jul to mid-Sep and peaked from 22 Aug – 3 Sep.  Over-wintering birds returning from previous years arrived before the onset of peak migration.  Mean body mass was 11.16 g (n= 164) before midday and 11.52 g (n= 178) after midday.  Mean body mass for all individuals at all times of day did not vary much by month (range= 11.1 g in Sep to 11.9 g in Apr).  Migrants and wintering birds gained mass at a rate of 0.07 ± 0.02-0.03 g/hr from dawn to dusk.  Maximum fat accumulation occurred Dec-Feb, and minimums occurred Apr – Jun.  Peak body molt (ventral tract) occurred in Jul, with heavy molt persisting into Aug and moderate molt persisting into Oct.  Heavy and moderate capital tract molt occurred 20 Aug – 3 Oct.  Apparently, most adult rectrix and remige molt occurred on the breeding grounds before fall migration commenced.  Mean adult wing and tail length are larger in Anchorage than elsewhere in North America.  The data suggest Red-breasted Nuthatches migrating through Anchorage were produced locally, rather than from irruptions from Canada or elsewhere in Alaska.