Fall migration monitoring in the middle of summer!
August 15, marked the first day of the 2020 fall migration monitoring season and “yours truly” opened up all the 15 mist nets as per the regular CMMN protocol. For more information about the protocol that binds us, see; https://www.birdscanada.org/bird-science/canadian-migration-monitoring-network-cmmn/
On that first day, it took nearly 30 minutes to open the nets, a time that is slowly whittled down by a few minutes each day as practice, practice, practice makes perfect.
This fall, a decision was made to run a normal fall monitoring protocol, as normal as can be: we are accepting volunteers, although only one at a time, as per COVID-19 compliance, with no overlap between volunteers. For the first couple of weeks, it appears that I will be on my own. However, it still more summer than fall and migration has not fully started in earnest.
So, why start so early with the fall migration monitoring protocol, you may ask? A good question, indeed! In fact, there are already some fall migrants on the move and in order to have the best monitoring results possible, it is essential to encompass the whole period of migration, from the first early birds to the last stragglers. For example, a Greater Yellowlegs was heard calling on August 16, already moving south from its boreal summer haunts.
Other species are not so easily separated between birds on the move and locals still enjoying their summer. For example, American Redstart, the “poster bird” of a local species, is very abundant on the Bruce Peninsula. In fact, the American Redstart is the signature bird of the local Huron Fringe Birding Festival, named one of the Top 100 birding festivals in North America. (see https://friendsofmacgregor.org/page/huron-fringe-birding-festival). All American Redstarts will eventually start their migration to warmer climes but it is difficult to know who is who – when an unmarked bird is captured in one of our nets if it is a local bird or one coming from away.
Bird banding days in mid-August are usually relatively quiet. However, on August 18, with cooler temperatures at night and in the early morning and a strong, constant North wind throughout the day, there was a notable movement of many birds, resulting in 30 birds of 14 species being captured and banded, including nine species of warblers. Most of the captured birds were young from this breeding year, so called Hatch-Year birds, and many were from species that breed on the Bruce Peninsula as well as further north. However, one Philadelphia Vireo was captured: it is a species most associated with the boreal forest, with very small numbers breeding on the northern Bruce Peninsula and Manitoulin island. It is possibly that this Philadelphia Vireo was our first “real” songbird migrant
Another “true” songbird migrant in the mist net, was the young Tennessee Warbler captured on August 19. Like the Philadelphia Vireo, is a boreal forest specialist (despite some summer records on the Bruce and Manitoulin), that enjoys good times during spruce budworm outbreaks.
Finally, on August 20th, short periods of rain and strong South winds forced us to close the nets after only one hour of opening. However, there were small flocks of birds passing through Cabot Head from time to time, with a great diversity, notably of warblers, with 10 species detected with my eyes and my binoculars. The most notable were Bay-breasted and Blackburnian Warblers, the former another spruce budworm boreal specialist. A Common Loon was also seen flying quickly towards the southern horizon.
Migration has indeed started at the Cabot Head Nature Reserve, albeit in subtle and discrete ways. It is as if the birds are telling us to keep enjoying summer, its warm and the days are still relatively long, but soon, with our ears down to the ground, and our eyes to the skies – we will be listening and observing for the slow change of temperature, length of day and weather events.
BPBO Station Scientist