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There’s exciting news in the Corrales Bosque Preserve although not all critters will be thrilled. An active Swainson’s Hawk nest has been documented here, possibly for the first time ever, according to Hawks Aloft Director Gail Garber.
On May 1, she told Corrales Comment about occupants of a Great Horned Owl nest, Cooper’s Hawks and visiting osprey, “but the most exciting thing just happened today: a large nest we have been watching for years now has a Swainson’s Hawk.
“That is the first documented Swainson’s Hawk that we’ve found in the Corrales Bosque. I’m super-excited about this.†It was spotted by Joan Hashimoto, a long-time Hawks Aloft collaborator. It is much larger than the more common Cooper’s Hawk.
The large raptor has taken over a long-vacant, deteriorating nest at the top of a tree close to the levee. In weeks before, Garber and Hashimoto had noticed that new sticks had been added to the old nest, so they were expecting a new occupant.
It’s at the top of a tall cottonwood where it likely will be invisible from the ground once the tree is fully leafed out, Garber said. She had suspected larger hawks might be visiting the preserve here, but could never determine which. “The reason, I think, is that the nests are so well hidden in the tops of the trees.â€
This year, the new hawk was spotted in the improved nest before the cottonwoods had fully leafed out. Garber said the Swainson’s Hawk spends part of the year in Argentina, some 6,000 miles away, migrating round trip every year. Among raptors, Swainson’s are among the last to arrive in New Mexico in the spring, Garber added.
“During the spring, they feed their young the same things the other raptors feed theirs. They eat lizards, snakes and other birds and small mammals and things like that. But when the grasshoppers bloom in the summer, they switch their diet to almost exclusively grasshoppers. So their nests are generally adjacent to open fields because that’s where they would find the insects they would normally eat. In the fall, when the grasshoppers die, they migrate back to Argentina, leaving here by September.
“The ones we spotted today will have 32 days from now tor their eggs to hatch and the young will be fledging in mid-July, and by September, they’ll be gone. And the young go before the parents.†As exciting as that discovery is for Corrales birdwatchers, they were a-flutter earlier when a Great Horned Owl nest near the Corrales Riverside Drain (“Clear Ditchâ€) produced newly-hatched chicks in early May.
“Eggs in the nest have hatched and the young owls are starting to come out of the nest,†Sarah Sadler reported May 4. “It has been quite the community event. I’ve been calling them the ‘royal owlets because their births were so highly anticipated. Best times to see them are about 7 to 8 p.m. before sunset. Best time to see the people seeing the nest are pretty much all day.â€
Sadler said the nest is along the Sandoval Lateral irrigation ditch that parallels the Riverside Drain, south of Dixon Road. Garber had anticipated this past winter would be a “really good one for birds†as a result of prolonged flooding in the bosque. “We were expecting a bumper crop of berries on the Russian Olives and New Mexico Olive. But really that didn’t happen.
“Consequently bird number across the bosque were very, very low,†she said, cautioning that her observation is anecdotal, not based on statistical bird counts.
She and Hashimoto regularly survey the preserve for raptors from Dixon Road south to Alameda Bridge since 2004. But it’s hard to produce comparable numbers because conditions in the bosque change considerably from year to year, she explained. “Last yeat, of course, the bosque was largely flooded in that area, so we couldn’t even get to some of the areas very well.
“This year, we’re out there looking for raptors, and Cooper’s  Hawks are just now starting to sit on their nests. That’s the most common raptor that we have in the bosque here.†Great Horned Owl chicks can scramble out of their nest within a few weeks of hatching. Using claws on their feet, they can climb into trees and shrubs to hide, Garber explained.
When grown, the owls “can eat everything, including people’s cats.They don’t see Fluffy as anything other than food. They also eat skunks… they have a very poorly developed sense of smell.â€