With kestrel research this year we’ve made a concerted effort to capture and identify or band all adult kestrels. We also needed to visit newly hatched boxes to determine the day of hatching. Determining the day of hatching determines the banding and tagging window. This requires going into the field a couple times a week to visit all the active boxes, which means my free days are typically busier than the days I work.
On this particular day a few weeks ago, we were joined by two by two turtlers (people who work with turtles; verb is to turtle.) for a day of kestreling (to specifically seek out kestrels).
Catching adults involves the use of a modified butterfly net. A chosen individual (think shortest straw or Hunger Games style selection process) assembles the net and proceeds on the quest to sneak up to the box and slip the net over while the remainder of the team sits in the car and bets on your success. When you are successful, the entry hole is successfully blocked, allowing the team to drive up, scale a ladder, and remove any inhabitants.
On this particular day, I began learning how to remove the kestrels from the butterfly net which is a delicate process because kestrels have claws of death and they are none too pleased with you.
We determine whether the birds are returns from a previous year, new to the area, or banded by someone else. We measure wing and tail feather length and weigh the birds before release. In the event that it is a new bird, we also band and tag the bird.
With the checks at this age, we simply weight them. Their weight allows us to determine hatch date. At this time kestrels gain weight at a uniform rate so you can backtrack to figure out when hatching occurred. Then you return during the banding window to band and tag the chicks.
Here are the chicks we’ve pulled from one of the last boxes of the day. You can see how small and scrawny they are.
They’re pretty docile. They have no idea what is going on. There’s a bit of whimpering and murmuring, but nothing like the older chicks or the adults! Once the measurements are complete, we return them to the boxes. At this particular box there were 4 chicks that were hatched and 1 egg.
I climbed back up to return the four to the nest and this is what I discovered:
In the moments we had them down for weighing, the last egg hatched! This is a kestrel hatched moments ago!