The MAPS (Monitoring Avian Productivity and Survivorship) season is underway and interesting birds are being captured at all three of our sites. The breeding season is in full swing and the majority of birds being captured are showing strong breeding characteristics including brood patches and cloacal protuberances. Some species have already began molting their body and flight feathers in preparation for their migration back south in the fall.
On July 5th we captured our first juvenile birds of the summer at Old Baldy. Clay-colored Sparrows, a Yellow Warbler, and a Black-billed Magpie were the first young birds to be captured at the station. The juvenile magpie was especially feisty and once it started calling two adults came in to make sure we released their young in a timely manner.
There are multiple ways to tell juvenile birds from adults. Fleshy gapes, soft downy juvenile body feathers, and sometimes eye colour such as the blue eyes on the above magpie can all help to distinguish this year’s young. If all else fails skulling is a sure fire way to tell them apart. Young birds only have one layer of skull when they fledge and as they grow, a second layer starts to form at the back of the head and slowly covers the entire skull. This second layer can be seen through the skin of the bird when the feathers are gently moved out of the way. Though we skull every bird, it’s not always needed to help identify a young bird like was the case with this recently fledged Yellow Warbler.
During the MAPS season the vast majority of the bird species captured are quite expected and often birds are captured at the same sites year after year, but every once in a while something unexpected hits the net which is exactly what happened on July 5th at Old Baldy. A male Rose-breasted Grosbeak found its way into net 7! This was the first RBGR of the year for CHIP, a new banding tick for one of the banders, and the first time this species has been banded in the Cypress Hills during the MAPS Season. Later that same day a “Gambel’s” White-crowned Sparrow was also captured and banded which was an interesting and welcomed change from the frequently captured “Eastern” subspecies. This subspecies has only been captured once in the park during MAPS back in 2010 so it too was quite unexpected.
Quiz — What type of bird nest is this?