Mixed Winter Flocks

Mixed Winter Flocks

 

Many birds behave a bit differently in winter. Finding food in the winter is normally harder for many species, so their food gathering strategy changes in the colder months.  Plus, many birds have migrated to their wintering grounds, to places that often offer a different food source and competition for food is more challenging than on their summer nesting grounds.   

One strategy adopted by many species in winter is to forage for food in mixed groups.  Different species create loose groups that they move around in all day to glean insects, find seed, or whatever each species may eat.  It is often a mixture of birds from similar family groups such as warbler, and with similar size and forage technique, but at times some rather different types add to the mix.    

Small songbirds use this technique frequently in winter.  Bird species such as warblers, vireos, chickadees, titmice, wrens, and goldfinches seem to like each other’s company, and form small to large fast moving forage flocks.  They move from tree to tree together feeding on different foods such as insects, others on seed, and often they have niches in the trees themselves.  Some feed up high while others feed low, and therefore don’t compete as much.  It’s fascinating to see, and hear, these flocks appear out of nowhere, moving almost as one organism. Their call notes of fine chips and chatters seem to act as a way to keep the flock together.        

American Goldfinches can be a part of these flocks, but they often form their own flocks that include Pine Siskins, House Finches, and in some locations Lesser Goldfinches (not on the Upper Texas Coast). They often feed in tree tops for seed, or in grasses and weedy fields on seed.  They love old sunflower fields or unkempt pastures. 

The blackbirds, yes all those different black birds you see in summer, often gather in mixed species flocks all winter long.  They can include Great-tailed Grackles, Common Grackles, Red-winged Blackbird, Brewer’s Blackbirds, Brown-headed Cowbirds, and a few more less frequent species such as Bronzed Cowbirds and Yellow-headed Blackbirds.  Along the Upper Texas Coast you can also find Boat-tailed Grackles in some flocks, but to me they seem to keep more to themselves. These bird species can form huge flocks of thousands of birds, and often forage in agricultural fields and pastures in more rural locations. They move as one when they fly creating huge murmurations, flowing together in elegant, intricate patterns through the sky.  It is a spectacular sight to see!  

Another group of birds that often flock together in winter are ducks.  There are many species that winter along the Texas coast. Some prefer shallow water (dabbling ducks) and some deeper water (diving ducks), therefore they don’t all join together.  You can at times find rafts of ducks with a few, or up to ten or more species, all mixed together and feeding on ponds or lakes.  Same goes for the bays and estuaries along the coast, and for some species on the near shore waters of the gulf.  It’s a beautiful sight with those different colors and plumages all mixed together.

So, the big question is… why?  The simple and number one answer is… safety in numbers.  A predator can only pick off one at a time, so your chances are much better in a large group.  Every time I do a Gulf Coast Bird Observatory survey of birds in the winter, I love seeing the wintering birds doing their daily thing, often in these flocks.  I hope you are enjoying them as well!    

 

Martin Hagne is the Executive Director of the Gulf Coast Bird Observatory. The GCBO is a non-profit organization dedicated to saving the birds and their habitats along the entire Gulf Coast, and beyond into their Central and South America wintering grounds.   

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