Invasion of the bohemian waxwings at Henrys Fork near Ashton
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As I approached the Vernon Bridge spanning the Henrys Fork of the Snake River west of Ashton, I noticed hundreds of birds picking off insects flying over the river. With temperatures in the 40s, the insects were hatching and the nomadic bohemian waxwings were enjoying them. There were a few American robins and cedar waxwings joining the large flocks of bohemians eating dried berries along the shore.
I followed the country roads to the Chester Dam, seeing bohemians at every stop. Most of them were gorging on the dried hawthorn and chokecherries that they could find along the river. On the way to the Chester Dam, the road runs between the river and a canal, which has warm seeps trickling into it. It appeared that thousands of waxwings covered the berry producing bushes and even into the few huge cottonwoods with flocks continually joining them.
The road to the Chester Dam was covered with soft snow because of the warm temperatures, so I decided to walk the mile to it. As I walked, I watched and photographed waxwings as they would fly from their perches to the warm seeps. It was almost like a two-way river as the birds went back and forth from their food to the trees and then to the canal where they would bathe and get a drink. It was exciting to watch.
The berries are very high in sugar but low in other nutrients, so the birds need to eat a lot of them to get their health food, but they need to consume a lot of water to digest the dried fruit. They eat so much, but they never seem to get full. It is a fast digestive process with a lot of food flowing in and a lot of fertilizer flowing out. You do not want to stand under them while they are perched in large numbers high in trees.
The fruit they eat is also responsible for the color of the “wax” tips and the color of the barring of their wings. The colors on the wings and tails come from carotenoid pigment found in the berries they eat. Young Bohemians have white bars on their wings and only two or three wax tips on some of their wing feathers. As they grow older, the white bars turn yellow and more feathers obtain the red wax tips. The vivid colors on the males increase with age and make them more appealing to the female Bohemians.
Their name, “Bohemian,” comes from their behavior — not from where they come from. They breed in Alaska and northern Canada and are vagabonds during their non-breeding season, living what appears to be an unconventional and seemingly carefree lifestyle. They do not maintain breeding areas, but they usually only have one partner for each nesting season. They are guided by their stomach. They migrate to the find the best sources of food.
The thousands of birds I watched this week were involved in what is termed an “irruption” where great numbers of birds of a species migrate where food is abundant, consume it and move on. This winter, a lack of food in lower Canada has forced the Bohemians to travel as far as south as Utah and Arizona, which have also had irruptions this winter.
As I watched them this week, it appeared that they first fed mostly on dried chokecherries along the Henrys Fork. When those berries were gone, the birds turned to the hawthorn berries, followed by the lowly wild rose hips. By Thursday, it appeared most of the Bohemians had left the Ashton to Chester area, but they may be back; nobody knows. They left a few leftovers for the local American robins and the Cedar waxwings to finish up. If you know of an area that contains groves of berry loaded trees, watch for the Bohemians to come and strip them bare. They are beautiful and fun to watch.
By the way, there are only three species of waxwings worldwide – the Bohemians, the Cedar waxwings (which nest in southeastern Idaho) and the Japanese waxwing in eastern Asia.
