For example, VCE researchers study Bicknell’s Thrush. On Stratton Mountain, they banded a male, and renetted the same bird over two dozen times for the next ten years. Birds banded on Stratton have also been recaught in the Domincan Republic where they winter.
At the Wildlife Festival, they netted and banded a male Yellow-rumped Warbler. The bird was healthy. It had enough visible fat reserves, the onlookers were told, to make the rest of its journey, possibly to the Canadian boreal forest. Once it reaches its breeding territory and begins singing for a mate and defending a territory, it will use up those remaining reserves.
I have heard or read that sort of information before, but this time it woke me up. In the last two weeks, I have been watching the returning birds with a new appreciation and a new perspective.
On several occasions three males contested the same alder bush. They dashed about with lightning speed. When the claimant to the alder bush had successfully driven off intruders, he sang his full throated, “Sweet, sweet, sweet, I’m so sweet” - which is the mnemonic used by many birders to describe the song, even though there is nothing at all sweet about the serious conflicts taking place.
These birds had just completed a long and energy-expensive journey from their wintering grounds. Now they engaged in energy-expensive territorial battles in the quest to obtain breeding rights to a female who would critically evaluate the quality of the territory each claimed plus the genetic quality exhibited in his song and his demeanor.
Not to short-change the female: when she arrives and begins her evaluation, she will also have completed a long and energy-expensive journey. She will then expend energy reserves in nest building and in energy-expensive production of eggs. She needs a mate who knows how to find and keep a territory with abundant food to replenish her energy needs and to feed her young.
As a bird watcher watching all of this activity, I am a rather self-indulgent, dilettante. I am there for the fun of it. But the birds pursue a very serious goal - extending their genetic life.
The Yellow Warblers were clearly expending a great deal of energy as they sought to establish and defend a breeding territory.
Birders often try to bring a bird into sight by pishing - “Pisshh, pisshh, pisshh.” Increasingly, modern technology allows birders to carry all bird songs in the field in a small, fit-in-the-pocket electronic gadget. The bird song can be played in the field. A singing Yellow Warbler does not know that it is hearing an electronic device; it thinks another male is intruding on its territory and quickly comes to investigate.
I confess that I pish, and that I sometimes play a recording to attract a bird. I do so less and less. As I come to understand the energy-expensive activity in which the birds are engaged, I realize that I am not helping the bird one bit by arousing or agitating him. It amounts to harassment; it results in a bird spending energy unnecessarily. Reluctantly I come to the conclusion that the use of electronics to attract birds, and probably pishing as well, is in a very gray ethical realm, and may be outright indefensible.
The neotropical migrants - the warblers, vireos, tanagers, thrushes, swallows, flycatchers - can make the expensive journey because they can fill empty habitat niches rich with protein to raise young and quickly rebuild their own reserves.
It will continue to be so, if those bipeds on the ground don’t screw it up.