Today featured a bit more diversity and the first Prothonotary warbler of the season, an adult female. We surprisingly only catch about a half dozen of these each fall, despite the fact that they breed on the Florida peninsula not too far from here. They generally move through the area early, in late August through about the middle of September.
We use multiple techniques for ageing and sexing birds in the hand. For example, we could tell the Prothonotary warbler was a female by plumage characteristics such as the amount of white in the tail and the green on the head blending with the back. The color of the flight feathers indicated an adult, and we also use a process called skulling to age birds. Young of the year have ‘windows’ in the top of their skulls because the bone has not completely filled in yet, similar to the soft spot human babies have when they are very young. The skull gradually fills in within the first 6 months or so of a bird’s life.
| SPECIES | NEW | RETURN | RECAP |
| Northern parula | 1 | – | 1 |
| Prothonotary warbler | 1 | – | – |
| Black & white warbler | 3 | – | – |
| Worm-eating warbler | 1 | – | – |
| Northern waterthrush | 1 | – | – |
| Ovenbird | 4 | – | – |
| Swainson’s warbler | – | – | 1 |
| # BIRDS CAPTURED | # SPECIES | # NETS | NET HOURS | CAPTURE RATE (BIRDS/100NH) | |
| DAILY TOTAL | 11 | 6 | 23 | 114 | 9.65 |
| SEASON TOTAL | 76 | 12 | 23 | 743 | 10.23 |
Nice! Can you post a photo of a bird with the ‘window’ in its head?
That is nearly impossible to photograph on a living bird. I can show the diagram of the skull windows in an upcoming post.