Migration is still on!

It is said that in North America there are migratory birds on the move in any month of the year with an ever so faint lull in June and December. Arctic breeding shorebirds for example, may start their southward migration as early as July, while Golden Eagles in Northern Québec may wait until November to leisurely fly to the Appalachians for the winter. 

The past week at Cabot Head definitely experienced large movements of birds, mostly reflected in numbers of birds banded (daily totals ranging from 61 to 90; two days with no banding because of bad weather). The ever-abundant American Redstart was the most frequently species banded with lots of females (both adult and young) and young males. Some of them will likely stay at Cabot Head but others will go on, as indicated by their fat reserves. Diversity of warblers was very good during the week with daily totals of 17 species achieved a few times. We were notably treated by a little influx of Blackburnian Warblers on the 24th with a daily total of 8 birds banded, including 5 caught in the same net at once. To put that number in perspective, that was more in one day than in the whole season of 15 spring seasons of the last 20 years. 

The busiest day of the week was May 29, a Sunday, when apparently birds don’t rest and relax. 90 birds of 22 species were banded that day with another 10 of 4 species recaptured. Once again, while the dominant species was American Redstart with 29 birds banded and 7 recaptured, there were also a lot of Flycatchers in the nets. We banded the first Eastern Wood-Pewee, a species more often heard and occasionally seen than captured. Spring totals vary between one and three birds. A total of 7 Yellow-bellied Flycatchers were also banded, a species which always migrates relatively late in spring and is among the earliest to fly back south. That daily total has been achieved 3 times in the past, with records of 8 and 9 birds banded in a day on May 29, 2015 and May 29, 2012, respectively. Finally, there were 6 Traill’s and 3 Least Flycatchers banded on that busy Sunday. The FOY Gray-cheeked Thrush was captured on May 28 and the SOY (Second of the Year) was on May 30 detected through banding as well.

On May 30th, while the rapidly increasing wind forced us to close most of the nets and cut short a productive banding morning, we observed an extremely clean cut young Bald Eagle. Its plumage looked extraordinarily fresh, with not a nick or wear in the wing feathers. It actually appeared like a newly fledged Bald Eagle: beside the freshness of plumage, it had the slightly bulging secondaries compared to primaries (an attribute of young raptors) as well as the colour pattern of a young. How could that be when the local breeding pair of Bald Eagle is still sitting on the nest with maybe barely hatched young or even eggs? Bald Eagles have a broad breeding range covering most of North America (north of Mexico). Eagles in Florida are among the earliest to breed, laying eggs from December to early January. Through telemetry and band recoveries, it has been shown that young eagles can disperse north, as far as central Quebec and Ontario. Could this Bald Eagle come from Florida? The timing would just work if its parents started in the early days of December: Incubation lasts about 35 days, with nestlings in Florida fledging at about 11 weeks and remaining with their parents for another 4 to 11 weeks. If that bird had an independent streak, it could have left in late April or early May, although that would mean covering well over 2,000km as the eagle flies to reach Cabot Head in a month. Florida young eagles are known to disperse northward but Ms. Google is not giving me a lot of precise information on the topic: a 2008 paper in the Wilson Journal of Ornithology presents results on 52 recently fledged Bald Eagles tagged with satellite transmitters during 1997-2001 on the Gulf Coast of Florida (near Tampa Bay). They began their first migration from April to June with a median date of May 24 with average distances achieved dependent on routes followed (coastal vs. mountain). Birds following the Appalachians Mountains migrated further, with an average of 2,112km. One eagle spent the summer 4,146 km north of Florida in coastal Labrador while another one traveled only 340 km and spent the summer in the middle of South Carolina. Unfortunately, the paper doesn’t give any details on rate of migration and distances covered by day. Nonetheless, I feel confident that the Bald Eagle observed was a recently fledged bird, all the more when I could watch it perched in a tree with two other immature Bald Eagles. So, being a bird from Florida seems to be in the realm of possibilities.