The last View of the season from Jenna Dodge:
The start of August marks that time of year when we prepare to say farewell to all our young peregrines around Mount Desert Island as they commence their exodus southward. Along the way, they will join many other raptor species in the sky with the hopes of travelling far away from their breeding and natal grounds to warmer climates for the winter season. The wandering falcon is synonymous with a peregrine; due to the nature of their long-distance migrations, they have been marked with this special epitaph and certainly live up to it. In late summer and early autumn, this species can travel as far south as Central or South America in a relatively short time period and will retrace their journey back to breeding grounds the following spring. There are two main factors that help them achieve this amazing feat: weather and evolutionary adaptations.
A shift in wind direction accompanies the change of season here in the Northeast. As we enter into fall, strong gusts of wind coming from the north will push our falcons toward their southern destinations along the coastline; this jagged North American boundary serves as a route for many raptors and a key landmark to keep them on course. In addition to this, as the sun rises throughout the day, temperatures increase, which cause the formation of thermals, columns of warm, rising air, that boost our peregrines’ wings upward and enable many raptor species to enjoy a free ride in the sky. Due to this, all birds of prey will migrate only during the daytime so they can use the full extent of their wings whilst exploiting these thermals.
Wing shape and size are essential during migration and are strong determinants in the type of flight a bird will employ to head southward. The classic falcon outline is a sharp, sickle-shaped wing, which was designed to employ a partial-power gliding flight; they will use powered flight to supplement gliding from thermal to thermal when that is not an option. Furthermore, birds have hollow bones, which make their skeleton very lightweight to improve the efficiency required for an energy-costly flight. Immense reservoirs of fuel, which comes in the form of fat, are needed to complete their many-thousand-mile trek. Prior to and during migration, many bird species will bulk up their fat reserves not only to ensure a triumphant flight but also to keep warm and avoid starvation.
Although many details of migration remain a mystery to us animals chained to the land, the information we have gathered throughout the years is from a combination of banding birds, tracking them with radio telemetry, and observation closely. Due to thermals forming along mountain sides, many migratory birds cross over summits along the East Coast including Cadillac Mountain, which is a prime site to watch the sky heavily spotted with raptors from late summer to early fall. The Precipice opens Tuesday, July 28, and Peregrine Watch will continue throughout this week. Please join us starting August 19 to take part in HawkWatch on top of Cadillac Mountain, and with your help we may contribute to the pool of knowledge surrounding migration.