Juvenile Myrtle Warbler
Fall migration has officially begun! While we are still wrapping up our MAPS (Monitoring Avian Productivity and Survivorship) Breeding Bird program, the birds are already departing the boreal forest. Where the forest was once alive with beautiful bird songs, we now hear the sharp chips of foraging birds and the begging calls of juvenile birds looking for food from their dedicated parents. While some late breeders may still have young in the nest, many of these young birds are already gearing up for their first migration.
Our Fall Migration Monitoring Program started up on July 12th and it has been very busy young warblers actively migrating already. As insects get less abundant in the boreal forest, warblers are some of the first species to depart. Warbler species top the banding leaderboard so far including the Myrtle warbler (Yellow-rumped warbler) followed closely by Black and White warblers, Tennessee warblers, Yellow warblers and Ovenbirds. One of the most abundant warblers in North America and the top bird banded at the LSLBO, the Myrtle warbler is easily identified by the bright yellow patches on their rump and flanks as well as distinctive white spots on their tails. This resourceful warbler species is usually one of the first warblers to arrive in the spring and the last one that we will see in the fall. While other warbler species juveniles tend to stick close to home for a while after they leave the nest with their parents caring for them, juvenile myrtle warblers are adventurers. As soon as they fledge, they will begin to migrate in waves past our station even before they have fully finished molting their juvenile plumage and getting their distinctive yellow rumps. Their “Leave Early” strategy isn’t really driven by the fact that they have a long way to travel this fall. Myrtle warblers are the only warbler able to digest the waxes in bayberries and Wax myrtles (hence their name) which enables them to overwinter much farther north than other insectivorous warblers who need to travel to the tropics of Central and South America.
Juvenile Tennessee Warbler
Another reason that we are capturing so many juvenile birds at the start of fall migration as these young birds will depart the breeding grounds before their parents. Once a young bird is strong enough, it will instinctively begin to travel south without ever having done so before. Their parents will head off later once they have recovered from a busy breeding season. Over half of these juvenile birds won’t survive their first migration as they are simply less experienced migrators. The good news is that if they survive their first migration, the odds of making it the next time are much higher, and they can have a fairly long lifespan.
To experience fall migration at the LSLBO, you can join us for our Public Bird Observatory Tours every Wednesdays and Saturdays from 9 to 11 am until the end of August. For more information, you can call the Boreal Centre at 780-849-8240
By Patti Campsall. Executive Director
