Watch out: it’s a fall-out!! (of the bird kind)
After a long wait, the weather finally improved on May 4 for a few days, and the birds, they were a-coming! As the cliche goes, the dam has broken and birds were taking advantage of the good conditions to flood North. From May 4 to 8, there were daily new arrivals, and we were busy banding; with a total of 329 birds during this period.
The long-distance migrants started to finally arrive! It began with the FOY Black-and-white Warbler and Barn Swallow on May 4. But the trickle became a gush the following day (to keep the cliche going!): five new species of warblers were detected during the monitoring period: Nashville, Black-throated Green and Blackburnian Warblers, Ovenbird, and Northern Waterthrush. And one male Yellow Warbler was seen in the afternoon too. It felt good to warmly welcome back our summer visitors (admittedly, a strange welcome in some ways, as they got tangled in a mist nets and ended up with a tiny aluminum bracelet around their leg). On May 5, we banded the then season record high of 138 birds of 18 species.
The good times kept rolling over the following days. On May 6, the FOY joy was: a male Scarlet Tanager, briefly flying by in front of us; a Vesper Sparrow hiding in a bush at the tip; a Warbling Vireo, quickly spotted by a visitor from McGill Bird Observatory; a Least Flycatcher, heard – once – and observed very briefly; and Cape May Warbler. In the afternoon, after the monitoring period had ended – but not our desire to see additional newly arrived birds – we observed the beautiful Northern Parula (several individuals) and one male Black-throated Blue Warbler. It made for a respectable 11 species of warblers detected that day!
Diversity was not as high for the following two days, and the numbers captured were in free fall as well, especially on May 8, when an East wind picked up; a harbinger of bad weather. After an amazing streak of five days of good weather, sun and blue sky (but not quite warmth: let’s not be too greedy here), the rain came back with a vengeance! It poured all day on May 9, stopping all migration in its tracks and confining the brave crew at BPBO huddled by the wood stove.
May 10 dawned under an overcast sky, fog patches, and a strong West wind; conditions I typically do not think as being conducive for migration. And, indeed, for the first half of the morning, there were a few birds around, with some catches, but nothing major. Suddenly, it all changed: birds were everywhere, falling down from the sky and filling the nets more quickly than we could extract them. Why this massive fall-out happened, I am not sure, but it was massive! A “fall-out” is the result of severe weather preventing birds from continuing their migratory flight and causing them to drop down on the ground to rest, take shelter, and feed. Such events can impact large numbers of birds of many species at the same time, notably after crossing large bodies of water, like the Gulf of Mexico, or it might be more subtle and not as easily detected, affecting only a few species. It is possible that the fog and West wind that day at Cabot Head compelled birds to drop down to the ground. The result, for us, was a mad rush to get the dozens of birds quickly and safely out of the nets and to band them as efficiently and gently as possible. After many hours of non-stop extracting and banding, we finally closed all the nets and tallied our efforts.
We banded 261 birds of 20 species on that day; the highest one-day total for the season and the second-highest one-day total ever. And almost all of the captures were in the second half, that is, in about three hours of banding! A few specific one-day records were also pulverized: 36 Nashville Warblers were banded, while the previous record was 33 birds on May 13, 2002; 49 Yellow-rumped Warblers got banded, slightly more than the 45 of May 21, 2002; an astounding 16 Cape May Warblers were banded, compared to the previous high of 5 birds on May 24, 2005; finally, an unbelievable 98 Palm Warblers were banded, smashing the previous record of 30 birds on May 14, 2002. That total of Palm Warbler is actually higher than the total of the whole season for all previous Springs, except two!! In one day, we thus banded more Palm Warblers than we usually band over the course of a typical entire Spring season.
It was an exhilarating, but also exhausting, day! These days really exemplify the true magnitude of bird migration: we are very often only seeing the tiniest tip of the iceberg (to keep on using as many cliches as possible) when we observe birds during migration.
Most of the FOY on that whirlwind of a day were birds caught in the nets: we did not have much time to leisurely observe and otherwise enjoy the show. One American Redstart was thus banded: the first arrival of this species has almost always been between May 8 and 10 and, this year, it again followed the « tradition ». We also heard the first Rose-breasted Grosbeak of the season.
The warbler tally for May 10 was 14 species, with an additional one, Chestnut-sided Warbler seen in the afternoon. It was certainly an exciting day!
There were still quite a few birds the following day, with 41 banded and a good diversity. But no new species. On that Sunday, May 12, overcast skies and cold weather have returned, with more rain in the forecast. It is all quiet in the Cabot Head front: we are catching our breaths, waiting for the next pulse of bird life!