Now that we seem to have put the bulk of winter behind us, we can all look toward spring with welcome expectation. Hip pocket indicators abound, hinting of seasonal change. Some seek the first robin, others might use the first thunderstorm as the sign. A tulip poking up certainly works, as does the first pass through the field with the plow.
For birders, the arrival of snow geese gets the blood pulsing and western meadowlarks singing on fence posts is welcome music to the ears. But nothing quite excites the senses as much as the arrival of a group of neotropical migrants known as warblers. I might get some disagreements from the local aficionados but I would argue there is no other group whose migration is more looked forward to each spring. There really are no other families of North American birds which exhibit such a palette full of brilliant colors combined with exceptionally varied singing abilities.
The first has already made an appearance. Right on schedule, yellow-rumped warblers (Dendroica coronata) began trickling into the state over two weeks ago. The yellow-rumped warbler (affectionately known as "butterbutt") is the guaranteed first arrival of the clan. It's a little bird with a white throat, yellow sides and rump, black mask and flank streaking, and a charcoal gray back.
(Note: Older field guides won't mention this bird. That's because the myrtle and Audubon's warblers were combined several years into the superspecies we know today as yellow-rumped warbler.)
Most of the birds which spend all or part of the year in North Dakota depart during the fall months as everyone knows. Many of these migrants are merely spending the winter in the southern states thereby avoiding the harsh conditions of the Northern Plains. Most warblers go even farther, heading to the Caribbean, or Central and South America. But a handful of hardy warblers don't go that far, merely exiting northern nesting grounds for the southern U.S. The yellow-rump is one of these.
By choosing to winter farther north, this bird needed some dietary adjustments. Somewhere along the line the yellow-rump adapted to become the only warbler capable of digesting the waxes found on some fruit, a handy tool if you aren't heading to the tropics.
It's a conifer specialist during the breeding season, where it can be found from Alaska east to the Canadian Maritimes. In North Dakota this small insect-eater has been documented nesting only in the extreme northern edges of the state, namely the Pembina gorge area and the Turtle Mountains.
During migration, however, the bird is virtually anywhere there are trees of any kind and in great numbers. I heard my first yellow-rumped warbler on the 17th of this month. And it was in the usual place - fairly high up in a tree on smaller branches.
A person can just about set a watch by the coincident occurrence of blooming trees and yellow-rumps' arrivals. I'm sure this relationship has evolutionary roots borne of eons of trial and error. As soon as our trees begin to burst their flower buds (American elms and cottonwoods have been flowering for quite a while) the yellow-rumps are here.
It only makes sense. If you are a critter dependent upon insects for your very survival, it behooves you to time your arrival with the very first plant growth. Without green plants, there are no bugs.
In the next four weeks or so we can expect up to 25 species of warblers to pass through the Red River Valley. From ground-hugging ovenbirds which walk like tiny chickens, to the brilliant orange of Blackburnian warblers singing from the treetops, warblers will have left tropical locations for breeding locations all over northern North America. Most will be showing off tropical colors. I suspect it's this vibrant feathering which so excites the bird lovers. And now that the vanguards - the yellow-rumps - have shown up, anticipation is building for the rest.