It’s time to find out just what our gulls have been up to since we attached GPS tags. In our first round of tagging, we sent out five tags on five separate Herring Gulls. The tags we used are useful because they are lightweight, but they don’t transmit the data directly to us. Instead, we have to catch our gulls again.
We started by watching the nest. Both gull parents will help incubate the eggs, trading off throughout the day. The gull not on the nest generally heads out to forage for food. However, we only tagged one gull from each nest, so it’s important that we only set the trap up when the right gull of the pair is taking his or her turn at incubation. Thankfully, the GPS tags are easy to see from a distance.
Once we know the right gull is in the area, we set the gull trap up, just like before. We were hoping they wouldn’t get trap shy and refuse the sit on their eggs when the trap was present. Luckily, our first tagged gull was caught less than an hour after we set up the trap!
The tags were removed by cutting off the small tuft of feathers to which they were taped. Don’t worry – birds regularly replaced their feathers, so the cut ones will fall out and be replaced with new ones.
After downloading the data from the tag, what we found was pretty cool: our first gull’s foraging trips were more than 15 miles long. She stuck to the mainland coast, mostly between St. George and Rockland. Her trips sometimes took her more than four hours!
In the end, we recovered three of the first five tags we sent out, and none of the gulls followed the same paths. One gull went straight up to Warren, ME several times over a few days. That’s a round-trip distance of almost 40 miles. We think he might have been looking for spawning alewives.
The third gull stayed local and barely left the waters around Metinic Island – it looks like she preferred feasting on the spawning polychaete sand worms just offshore.
We also lost two tags – the gulls managed to pull them off, so it looks like we need to come up with a new way to attach the tags. Our next step is to design a harness for the tags that the gulls can’t rip or tear. Hopefully we’ll have more news about our wandering gulls before the season is over.
Metinic also has plenty of terns and guillemots – expect to start hearing about them soon!