By Staff
Over the last several weeks I've noticed the birds gathering into flocks. All summer long the sparrows, goldfinches and house finches came to our feeders in pairs and small family groups.
Now flocks of forty or fifty launch continual assaults on the corn, thistle and sunflower feeders. Large flocks of birds are a fall ritual we're all familiar with. I've been wondering, though, why do birds flock together in the fall?
The first response to that question is because they're getting ready to migrate. Yea, so? They could just as well head south on their own, couldn't they?
In addition, many of the birds that come together like English sparrows, starlings, house and gold finches do''t migrate at all. Upon looking into this, it appears no one really knows.
There are a few plausible theories that may explain given incidences of flocking behavior.
For instance, it's widely accepted that ducks, geese and cranes gather in groups and fly in V formation to reduce wind resistance.
The lead bird "breaks trail," if you will, making it easier for the others. A number of the experienced adults take turns at this duty, switching regularly for breaks.
Also, it's believed the young birds must actually learn the correct migration route from the older lead birds. It makes sense to hold this Orienteering 101 class in a large session by flocking together.
That theory doesn't wash for most other birds, though. Those immense, mixed flocks of blackbirds, grackles, cowbirds and others filling the fall skies don't fly in any type of wind breaking formation.
Some speculate these birds migrate in flocks so they can huddle together for warmth when roosting. Considering the relatively mild temperatures they encounter during migration and the wonderful insulation provided by fluffed feathers I can't give this thought much credence.
In addition, most of these birds migrate at night, feed in the morning and evening and only roost during the warmest part of the day.
And what about birds such as hawks and many of the song bird species that migrate in just loose, haphazard flocks? They don't huddle together shivering on the roost.
Another common theory is birds flock together during migration because it's a more efficient way to find food in unfamiliar territory.
Hundreds or thousands of cooperating eyes are more likely to find food sources than just a few. Perhaps, but they also have to find proportionately more of it so it seems to me that would be an even wash at best.
A more plausible reason is safety in numbers.When you're just one among thousands you're chances of being singled out by that hawk are pretty slim.
If that's the case, though, why don't all birds live in flocks year around?
We still haven't gotten to my feeder raiding sparrows and finches that flock together in the fall but don't migrate. The predominant theory is for finding food.
The flock can split up and go on the prowl. When a significant food source is located the word goes out and the flock comes together to take advantage of it.
Similar, even more remarkable behavior has been noted in less urban birds during the lean winter months. For instance, a dominant pair of chickadees often leads a mixed species, "winter forage flock."
This consists of a half dozen or more family members, perhaps several downy woodpeckers, a few white breasted nuthatches and maybe a brown creeper or two.
All these species have similar diets. Each day this unlikely coterie loosely gathers to search for food, keeping track of each other by calling back and forth. This explains these birds vocalizing during the winter when most other birds are devoutly silent.
My favorite theory for fall flocking, though, is it's simply a social event on the order of the old mountain man rendezvous.
It gives birds of a feather a chance to get together, share news, speculate on the approaching winter weather, strike up new friendships and, most importantly, make arrangements for some whoopy come spring.
What better way to keep the gene pool diverse? Carpe diem.