Two days ago, I did a Yellow-billed Cuckoo survey at one of our Cibola National Wildlife Refuge sites called “Crane Roost.” I had vague/traumatic memories of this site from last year, running away from very small yet annoying mosquitoes. This survey was no different. As soon as you even think about entering the mesquite or cottonwood/willow stands, mosquitoes are buzzing in your ear and finding any inch of bare skin to bite. These little bloodsuckers were not nearly as large as the ones I just had to deal with in Idaho, but they were still a pain! Regardless, the survey went very well! As soon as I played my first call on my first stop, a nearby cuckoo started its “coo” call, and another started in the distance. It is thought that only females make the “coo” call (almost like a dove but more repetitive), but no one knows for sure. I encountered 3 other coo-ing cuckoos throughout the site, all of which were very responsive, which makes them good candidates for capture. On my last survey point, one flew right over to me, and started excessively coo-ing. It was unbanded, and probably un-paired, since it didn’t show any aggression or territoriality. I moved on and found 2 more of my coo-ing birds, and those were unbanded as well. All three birds seemed to have a defined territory, and often called back and forth to each other, probably letting the other know it was still there. While looking for the fourth bird I detected on my survey, my playback call was answered by a contact call (the classic “kuk-kuk-kuk-kuk-kowlp-kowlp-kowlp” cuckoo call). This area overlapped with the territory of a coo-ing bird, so there is potentially a pair in the area. At one point, there was a delayed voice exchange. But after walking all through the thick mesquite, the birds quieted down and never alarm called at me. Cuckoos are a hard nut to crack though, and it is really hard to say what is going on at a site from only one day of observation.
Three days ago, I radio-tracked a bird that has been jumping around one of our sites, named GRE. It was caught near a known nest that was being sat on by DG, another transmittered bird, so there was potential that it was DG’s mate. I sat near the nest in some camo, but of course DG figured out I was there and I had to reposition in the thick willows where he couldn’t see me as I radio-tracked. With my view of the nest obstructed, I wasn’t quite sure what was happening, but it sounded like GRE was very nearby DG’s nest after she had come off her roost about 200 meters away. The birds were doing vocal exchanges, and switching places near the nest quite a bit, so it looked like GRE was probably on the nest. DG is very smart though, and very territorial, so I had to be super sneaky and quiet under my camo; because he knew I was there, he didn’t go very far away.
Eventually when it seemed like DG left the nest area, GRE came back in. It really sounded like GRE was on the nest, so I walked in for a better look since DG seemed to be out of earshot. Sure enough, a bird with a transmitter was sitting on it, and GRE’s signal was coming right from the nest; DG was at least 150 meters away! Within minutes, DG arrived, as if he somehow knew an intruder was near his nest. He started knocking (a cuckoo alarm call), so I backed off and let them figure things out. DG took GRE’s place on the nest (as if to say “I’ll do it you nincompoop!”), and GRE went off foraging. It really looks like DG is the more territorial of the two birds, and spends much more time on the nest than GRE. There is one other nest with unknown ownership, so sitting by it may be the best option to find out if any of our other telemetry birds are sitting on it. Cuckoo telemetry is very tricky. You have to stay far enough away so that you aren’t disturbing the bird, but close enough to understand what is happening. The best thing to do is to find a small open area in good cover (like the short/dense willow!), and stay there as long as possible. As long as you aren’t moving, you can get a good sense of the places your cuckoo is visiting/re-visiting, or sitting for long periods of time. Of course, this is easier said than done, and just when you feel like you get into a great position, your cuckoo books it. If a cuckoo re-visits its roost location a few hours after getting off roost, chances are it is returning to a nest. Or, if it doesn’t seem to be doing much at sunrise, it may be taking over a nest-sitting shift.
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