It looks as though it is quite plausible that the Red Knots were wearing radio tags, although I'd dearly love to get a better look at them.
Barry Truitt is a Chief Conservation Scientist with the Nature Conservancy. He is involved in tagging Red Knots and was kind enough to answer my questions about Red Knots and radio tagging. Here, in part, is his reply to me.
It indeed does appear that at least one of the red knots in your photo is trailing a radio antennae. It is unclear to me that the other bird is trailing a radio antennae as the wire doesn't appear long enough to be an antennae. Like you, it would be hard to imagine two radio tagged birds flying together but stranger things have happened.
Yes indeed we did radio tag red knots (approximately 20) in Virginia this spring as part of a project looking at their migration stopover ecology here. I also believe that other researchers in Delaware might also be radio tagging red knots there. Radio tags are only adequate for close range tracking (5 to 10 kms) and last about 60 days before the battery dies or they fall off the bird so we are not presently following or tracking these birds.
A short time ago, last week actually, I was out at the Marcil Lake outflow with Leah. We had just seen our first Semi-palmated Plover of the year, and I was walking down the road trying to get some photos of it when two shorebirds flew over head.
As they flew by, I fired off a series of shots so I could identify them later. And while looking at the photos to do just that I noticed something unusual. Both birds seem to be trailing something behind them. Now the photos are not that great, as they were a long way off, but what ever is trailing them is visible in every photo.
My first thought on the ID was Red Phalarope, but the general consensus of the good birders I sent the photos to is that they are Red Knot. That is kind of cool in itself, as I've seen Red Knot up here, but always out at the floe edge, never near town. But still I wondered what exactly it is that is trailing the birds.
A couple of thoughts sprang immediately to mind, the first being that they were carrying nesting material. The problem with that theory is that most shorebirds that nest up here don't really build nests. Most of their "nests" are depressions on the ground or the vegetation. Couple that with the fact that they wouldn't really need to bring nesting material if they did use it, as it would be likely be abundant where they were. These birds were traveling.
The, somewhat related, thought that I had was that the birds were carrying grass (or other vegetation) as a mating ritual. Many birds do this, you often see males with vegetation in their beaks while displaying to females. It doesn't take much of a leap to figure out why this evolved, as a way of showing their fitness to the female as a gatherer/builder of nest.
But, I have no idea with shorebirds do this, and certainly I have no idea if Red Knot do. I am, quite simply, stumped.
But last night, I was asking the incomparable Dick Cannings, what he thought, and he came up with a most intriguing and interesting possibility. Dick wondered if they might be antennae from radio tags. It isn't something I even considered, but Red Knot, which are suffering steep declines, have been tagged in tracking studies, and the photo in this article, certainly fits the profile.
One of the difficulties with this theory is that the chances would be extremely high that two tagged birds would be paired up. Misery loves company?
Here are a couple of photos, unless they're magnified, you don't get much of a sense of what's trailing them. If you can see it, what do you think it is?
Saturday we continued to explore outdoors, even though our snowmobile trip out on the land was cut short. Leah had headed to the water lake to fish, so Travis, Hilary and I headed inland to explore. We drove out to Second Bridge, where Lapland Longspurs launched themselves into the air, and floated down filling the sky with song.
As I'd only had the briefest of views of Horned Larks this spring, we turned around to the plateau between First and Second Bridges. Usually it is a pretty reliable spot for larks, but we didn't see any flying, or see any sign, so we parked and walked towards the river gorge.
I wasn't paying attention and was startled when we flushed a sandpiper, I saw the white rump flash and assumed it was White-rumped Sandpiper, but when I photographed it all the field marks said Baird's. They are, to me, difficult birds to separate at times, but when it flushed again I could see for sure it was a White-rumped. If nothing else it served to make me even more confused, were that possible.
There were several sandpipers in the area, at times there were four coursing through the sky, chasing each other. We stopped for some photos and then walked on, at which point I saw a bird scuttling along the ground and as I watched it in my binoculars it settled down in a clump of heather, just below me.
I quickly got the children ready and then we flushed her briefly. There in a little depression were four eggs, which seem impossibly large for a bird that small. Darkly mottled, they would be very hard to see if I hadn't known exactly where to look.
I quickly showed Travis and Hilary, photographed the nest and we backed up. Almost immediately she worked her way back to the nest, and with a pause just inches away, she watched as we continued to move off before settling back on the eggs.
It was an incredible experience for them, and the cap on a pretty good day.