Bird nomadism
One of the most striking features of bird migration is its regularity. Most populations of birds migrate on approximately the same dates, in the same directions, and for similar distances each year, with many individuals returning year-after-year to the same breeding and wintering localities (such a remarkable feat!). However, to have consistency, one needs predictability. Some bird species exploit habitats or food supplies that are highly variable in distribution and abundance from year-to-year. These so-called irruptive migrants show great flexibility in their movement patterns, leaving their breeding areas in varying proportions and at variable dates from year-to-year, and concentrating wherever resources are plentiful at that time. A major group of these feathered nomads are the boreal finches, which delight southern birders during their mass exodus in times of poor cone crops in their immense northern forest home.
At Cabot Head, we have noted the first inkling of a potentially strong flight year for Pine Siskins: large flocks of several dozens and up to 100 birds have been seen for a few days, notably on September 20 and 21. It is possible that these fast flying, scrappy and chattering little balls of energy will visit a bird feeder near you this winter. Read more about the upcoming winter’s finch forecast at https://finchnetwork.org/winter-finch-forecast-2023-2024
On September 19, the season total of banded Red-eyed Vireo stood at 294. The following three days of banding inched the total upward to 299… and then, there was no unbanded REVI captured for two days, breaking a continuous streak of 39 days of captures (including in that total of days the four days with no banding at all) and leaving us fearful. Argh! The ridiculous tyranny of a round number: were we to reach 300? Luckily, one REVI, with beautiful blue legs unadorned by any human-made jewellery, was finally captured early in the day on September 25, the official 300th Red-eyed Vireo of the fall 2023 season! The 18-year-old record of 239 REVI has certainly been smashed to pieces. Who knows how long that new record will survive? Besides fall 2005, in the other 20 fall seasons, only six have totals above 100 REVI, with 131 birds in fall 2020 being the highest. The current record is thus exceptional and might stay in the record book for a long time. No vireos were captured or even observed on the day after the historic 300th: we are on the waning days of migration of this species at Cabot Head, although a few stragglers can occur in early October.
On September 22, a nice contingent of nine species of warblers were observed and/or banded. Here is the full list for our numerous warbler lovers (knowing full well that we won’t see most of them again until next May: a long wait for any lover): Orange-crowned, Tennessee, Magnolia, Cape May, Yellow-rumped, Palm, Bay-breasted Warblers, American Redstart, and Common Yellowthroat. This list has drastically shrunk in the last few days, with often only two or three species commonly detected now, Yellow-rumped Warbler being the most abundant.
American Pipits were seen during the last week most of the days, calling their name while flying (don’t you like it when birds sing their names? So much easier to identify them by sound) or walking the rocks on the beach with their characteristic gait.
The weather this week has been mostly sunny and warm, maybe even too warm: good weather is likely very good for migrating birds but not so much for expecting birders and banders. It seems that birds can simply keep on going and do not need to shelter and refuel as much, bringing down numbers caught. The weekly total is quite below average despite barely any mist net hours lost.
The forecast of the same warm weather for the next seven days was not welcomed with glee and joy by the staff here at Cabot Head: but it may be nice not to have to start bundling up and reaching into drawers for mitts and gloves. But being busy extracting and banding birds is why we are here. Bring them on!