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Wild Neighbors: Coots, Hawks and Gulls: A Day in the Food Chain

By Joe Eaton
Tuesday March 06, 2007

I’ve been birding in California long enough that new species are hard to come by. Every couple of years, something exotic may blow in from Siberia, but I’ve met just about all the natives and regular visitors. There are still surprises, though. Familiar birds—birds you think you know reasonably well—keep doing unexpected things. 

A week or so ago I went to the Flyway Festival at Mare Island, a sort of birder’s expo featuring conservation exhibitors, book and optics vendors, and field trips. I hooked up with a trip to an area that was new for me, the American Canyon Wetlands: tidal marsh with freshwater inflows abutting a new development. We saw a fair number of hawks, ducks, and saltmarsh songbirds, but nothing extraordinary for most of the morning. 

Then, as I was distracted by a male yellowthroat that kept popping in and out of the gumplant near the water’s edge, there was a commotion among a nearby flock of coots. Although the coots didn’t take wing, the whole flotilla was moving out into deeper water. What had cause the exodus was a hawk—a female northern harrier, we realized once someone had trained a scope on it—standing in the shallows, its feet planted on a submerged coot. 

In the right habitat—open grasslands, wet or dry—harriers can be common, especially in winter when local birds are augmented by migrants from the north. In more than 40 years of observation, I had never seen a harrier take a coot. I couldn’t recall even having read about it.  

Harriers are consummate rodent-hunters: their owl-like facial feathers allow them to target mice and voles by sound alone. They’ll sometimes pick up a vole’s nest, shake it to dislodge the occupant, and snag it as it drops. The books say rodents make up the bulk of a harrier’s diet, with a few songbirds thrown in.  

Clearly, though, there were exceptions—and I later found references to harriers drowning waterfowl. They’ve been known to kill birds as large as ducks, bitterns, grouse, and pheasants, with females taking on larger prey than males.  

The harrier stood there. There was no sign of struggle in the water. Once a peregrine falcon swooped over her, and she flinched. Then a western gull swam up to inspect. The gull dwarfed the hawk, but she held her ground, glaring over the shoulder at the larger bird. She didn’t seem to be trying to lift off with her prey, and we speculated as to whether she could get airborne with a pound and a half (according to the Sibley guide) of dead weight. A reporter from the Napa Register, who happened to be on hand, interviewed the witnesses. 

The harrier must have decided she couldn’t, and she took off. The gull moved in. The coot, not quite dead, gave one last spasmodic thrash as the gull towed it to a mudbar. That was it, though. The gull began working at the carcass; lacking a raptorial beak, it didn’t seem to be making a lot of headway. “This guy needs a can opener,” someone said.  

And then a new player arrived. An adult red-tailed hawk touched down and claimed possession of the coot. The gull, prudently, moved away—but not too far. Now the redtail had to deal with the aerodynamic issues. It stood there on the coot as if working things out. It was at about this point that we noticed that the tide was coming in. The water was up around the hawk’s thighs. It didn’t take off, and it wouldn’t give up the coot. And I thought, there has to be a metaphor here.  

Eventually, the redtail, like the harrier before it, gave up. Back came the gull. As the group of birders dispersed, it was working away at the coot again, sending a drift of black feathers into the water. Just another day in the food chain, and a salutary reminder that there can be a lot more to bird behavior than you’d ever guess from the field guides.  

 

 

A female northern harrier; males are gray and white. Photograph by Ned Kroeger.