Gulls' return signifies the first days of spring

Posted: Friday, April 09, 2010

On a recent Friday afternoon, we were viewing the NEXRAD radar images from the Kenai station on the National Weather Service Web page. My co-worker and I noticed some peculiar bands crossing Prince William Sound between Middleton Island and Whittier. At the time we were just a little intrigued and I told him they looked suspicious. It looked like we might be watching the first waves of waterfowl making their way to Alaska. I have looked at these signatures before and there is a lot of quality work being done around the country, especially in the Gulf of Mexico, where researchers have used radar to track large movements of song birds making landfall in the gulf-states like Louisiana and Texas. In most of those cases the birds travel at night, so you typically see them make landfall just before first light and then just after sunset you see a large exodus on the radar on an otherwise perfectly clear night.

Photo By Todd Eskelin, Kenai National Wildlife Refuge
Photo By Todd Eskelin, Kenai National Wildlife Refuge
This myriad of gulls was observed at Kenai River Flats April 28, 2008.

We were just speculating, but in this case it was daytime travel so our first thought was waterfowl. Now I cannot confirm it, but on Saturday morning when my co-worker was out birding the Kenai Flats with his family there was a surprising new addition to the bird assemblage that was not there a week earlier. Seemingly overnight, the number of glaucous-winged and herring gulls went from several hundred to well over 6,000.

I mention both of these species because here on the Kenai Peninsula we have a real problem separating the two species. Many of you are saying to yourself, "what a bonehead." Herring gulls have black wingtips and glaucous-winged gulls do not. But here on the Kenai Peninsula these two species readily hybridize and if you carefully inspect any congregation of large gulls on the Kenai you will see a myriad of hybrids between the two.

Herring gulls have large dark wingtips and light colored eyes. Glaucous-winged have no dark in the wingtips and dark eyes. Gulls on the Kenai have every combination you can imagine. You will see gulls with large black wingtips, but they have dark eyes. You will also see the other extreme with almost no black in the wingtips indicating glaucous-winged, but the lighter eyes more typical of a herring.

It is so confusing that back in the 70s researchers investigated the gulls at Skilak Lake to try and determine what type they were. They compared them to other museum specimens and found that after handling and examining a couple hundred gulls they were unable to find a specimen that was 100 percent pure of either species. Not only were they all hybrids, there were no pure species remaining at the colony and they were continuing to breed and back cross in genetic terms.

So where does that leave us when talking about Kenai Peninsula gulls? The largest glaucous-winged gull colony in the world is documented on Middleton Island with 12,500 birds.

There have been times when we have estimated the Kenai Flats gull population to be in the 35,000 to 40,000 range. That is certainly an unofficial count, but I think it is fair to say that Kenai can boast the largest glaucous-winged X herring hybrid gull colony in the world. The best part if the story is the fact that the gulls have returned, the rest of the birds are on there way, and I have many other birdies dancing around in my head waiting for the grass to show itself.

Todd Eskelin is a Biological Technician at the Kenai National Wildlife Refuge. He specializes in birds and has conducted research on songbirds in many areas of the state.

Previous Refuge Notebook articles can be viewed on the Refuge Web site, http://kenai.fws.gov/. You can check on local birds or report your bird sighting on the Kenai National Wildlife Refuge Birding Hotline at 907-262-2300.



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