2019 marked the 20th year of bird banding at Chico Basin Ranch. In the early years, banding occurred during the spring season only, with fall banding starting in 2008. There are some striking differences between spring and fall migration in terms of species composition, plumage patterns within species, and overall numbers. Banding stations that operate both spring and fall really help us illuminate and quantify those differences. For example, we tend to see greater numbers of birds overall during the fall. Why, you may ask? Well, most of those birds that migrated north in the spring have fledged young and are heading south with an influx of young birds in the population. Usually well over half of the birds we band in the fall are young birds on their first southward migration, and this year was no exception with young birds accounting for about 60% of all captures.

Fall this year was unusually warm, with temperatures in the high 80s and 90s extending through all of September. This seemed to delay migration activity in birds, as we had lower numbers overall this September at Chico and indeed across other Colorado banding stations as well. While the numbers were a bit down this fall, we did have some surprising birds, including two species that were new records for the banding station! We banded our first Red-headed Woodpecker (a young one lacking the distinctive red head) as well as our first Canyon Wren, a species fairly common in the foothills of Colorado but very unusual to find in the plains. The Canyon Wren was a new species not just for the banding station but for the entire ranch as well!

This fall season our nets opened on Sep 2nd and ran through Oct 4th (closed on Sundays). We banded a total of 734 birds of 53 species this fall (see Table 1 below for a breakdown by species). This is a fair bit lower than our fall season average of about 1100 birds, though still more than we banded in the spring (585 birds of 50 species). It’s difficult to attribute this to any one thing in particular, but the unusually warm weather did have us closing nets early on most days.

Our most commonly banded bird was the Wilson’s Warbler, accounting for 222 of our newly banded birds this fall. Without fail, this has been our most commonly banded bird every fall. One of the biggest differences between spring and fall seasons is the apparent flip-flop of Swainson’s Thrushes and Wilson’s Warblers; the thrushes dominate every spring with just a handful of Wilson’s Warblers, while in fall it’s quite the opposite. Our highlights for rare captures were definitely the Canyon Wren and Red-headed Woopecker, but we did have a few other rarities as well. A Western Palm Warbler towards the end of the season was just the 2nd fall banding record, while a Virginia’s Warbler was our 4th fall record. We also banded a hybrid Bullock’s x Baltimore Oriole, a hybrid that’s probably under-reported on Colorado’s eastern plains as the females (which this individual was) can be quite difficult to pick out.

Surprisingly, we did not have any recaptures from previous seasons or from other banding stations. We typically don’t have many, usually just 3-5 returning birds, but this was our first fall season to not have any recaptures (although several other seasons had just 1).

Thank you to all the visiting birders and educational groups that help make the banding station possible! We also owe a big thank you to lead bander Robert Snowden and our team of volunteers that helped him this fall. To find out about volunteer opportunities at the banding station, please contact colin.woolley@birdconservancy.org.

Table 1: Species breakdown of newly banded birds during Fall of 2019. The average of previous full seasons is also presented for comparison.