TREE SWALLOW (Iridoprocne bicolor) 



Tree swallows have glossy green-black backs and white underparts. Be- 

 cause of the abundance of aerial insects, on which they feed, they are 

 generally widely distributed throughout both parks. However, they nest 

 primarily in tree cavities of the aspen, in company with mountain blue- 

 birds, flickers, house wrens, and dusky flycatchers. In their incessant pur- 

 suit of insects, tree swallows glide in wide, flat circles, darting this way and 

 that in pursuit of their insect prey. Tree swallows are the first of their kind 

 to arrive in spring. Following pair formation, the pair selects a hole in a 

 tree and the female lays from four to six white eggs. The violet-green 

 swallow, which is also common in both parks, resembles the tree swallow, 

 but displays prominent white rump patches. 



free Swallow 



Willard E Dilley 



Barn Swall^ 



Bruce Pitcher 



BARN SWALLOW (Hirundo rustica) 



A handsome swallow with a blue-black back, cinnamon-buff underparts, 

 and a deeply forked tail, the barn swallow is the epitome of grace and ease 

 of flight. The barn swallow flies close to the ground in an undulating flight 

 pattern. While in flight this species often utters its musical, twittering 

 song. In Yellowstone and Grand Teton the barn swallow breeds in open 

 meadows and marshlands. In general coloration the barn swallow re- 

 sembles the cliff swallow, but the squarish tail and buffy forehead patch 

 and underparts readily distinguish the latter species. The nest of the barn 

 swallow is a mud cup lined with feathers. It is most often placed under a 

 bridge or upon the side of a cliff. 



43 



