Why the plumage at Henrys Lake may be more numerous than the fish this weekend

While the female Mountain Bluebird sat on its nest in a nest box placed on the west side of Henrys Lake, the male kept a vigil eye out for marauding Tree swallows. After chasing away a pair, he became bored, hungry or thirsty and flew off to the nearest watering hole.

It did not take long before the swallows were back, peering inside while the female bluebird hollered at them. When they did not leave, she came flying out of the nest hole and chased them off before sitting on the box waiting for her significant other to show up and do his job.

He returned and set up an observation location three posts away from the sitting mom and every time the swallows got guts enough to land on the box, he would attack. After about six unsuccessful attacks, he hit pay dirt, grabbing one of the swallows by the neck. They fell to the ground behind a bush as I tried unsuccessfully to get some shots of the battle.

All I got were some blurry blues of the short battle before the swallow escaped and flew off to find its mate. It joined the other one on a barbed wire, before they flew off looking for a kinder, gentler area. The bluebirds settled down with the male perching on the top of the nest box occasionally peeking in the hole, looking for an “atta-boy” from the Mrs.

The Mountain bluebird, the state bird of Idaho, are cavity nesters but they cannot excavate their own holes in trees so they have to use old woodpecker holes for natural nests. For these nesting cavities, they have to compete with not only swallows but starlings, flying squirrels and saw-whet owls. As with all birds, habitat determines the numbers of birds in an area.

During the 1970s, the estimated population of bluebirds dropped 70 percent due to the use of pesticides on insects, their main food source. Programs for building nest boxes were encouraged and the bluebirds around Henrys Lake have benefitted from members of the Boy Scouts building nests for their Eagle projects.

This spring, some new nest boxes have been added along the road that goes around Henrys Lake, but they were added after the male bluebirds had already staked out their territory. So most of them have set up camp in the older seasoned boxes while several pairs of the swallows are battling over the new ones.

The bright blue plumage of the male Mountain Bluebird makes it one of the most recognizable birds in this area, while the female is less recognizable with its grey breast, head and back mixed with bluish tint on the tail and wings. There is nothing brash or noisy about these beautiful birds as most of their calls are soft — almost a buzzing sound, pleasant to listen to — except when chewing out their forgetful partner.

Watching nest boxes can be very entertaining. Some of the best places to watch the battles and nesting activities of the bluebirds are, of course, Henrys Lake, Sand Creek Wildlife Management Area, and the Bone area east of Idaho Falls. Using your vehicle as a blind, you can park close to the nest box and the birds will ignore you and continue their normal activities.

Over the Memorial Day weekend, you can kill two birds with one stone: go fishing at Henrys Lake or the Sand Creek ponds north of St. Anthony, and during your non-fishing time, park near a bird house and enjoy the show. It may be more successful than the fishing.