SOUTH-BOUND BANK AND TREE SWALLOWS

     While watching wildlife at Lake Onalaska through a live camera and our computer screen, I noticed mixed flocks of bank swallows and tree swallows perched on the twigs of trees on an alluvial island in the lake.  They were all post-breeding birds gathering together early in August, prior to their migrations south ahead of the coming winter.  And because these swallow species are attracted to larger bodies of fresh water to catch and eat flying insects, the swallows' coming together at Lake Onalaska before drifting south is natural and inevitable.  

     The swallows were all aflutter on their roost between feeding forays after flying insects.  Those birds preened their feathers, socialized and rested and digested while on those trees.

     Lake Onalaska is a large backwater off the Mississippi River in Wisconsin.  It is a good wildlife habitat the year around, but especially in summer.

     That congregation of bank swallows and tree swallows, resting in trees with their youngsters at Onalaska, had raised those young ones earlier that summer.  When I saw them, they were resting from migrating and catching flying insects in mid-air to bolster their fat reserves and stamina for the almost daily flight south to where flying insects are available when winter prevails in the north.  Every day they must alternate drifting farther south, ingesting flying insects, and resting, as they were at Lake Onalaska.  They are always busy.

     Each petite bank swallow is brown on top, white below and has a brown band across its chest.  Each beautiful tree swallow is, more or less, metallic-blue on top and white below.      

     Both these kinds of swallows rear offspring near larger bodies of water across much of North America.  But they do so in different niches.  The swallows find flying insects in abundance around water in summer.  One might think these swallow species would compete for food when raising chicks, and they do a bit.  But bank swallows nest in widely scattered colonies in banks of soil or sand while tree swallows hatch young singly in tree cavities and bird boxes.  Nest sites determine whether these swallow species compete for food or not.

     Each pair of bank swallows uses its tiny nails and beaks to dig out a shaft about two to three feet deep into a soil or sand bank along a waterway or road.  Many banks have scores of bank swallow tunnels in them.  And each pair creates a nursery of dried grass at the end of that burrow.

     The graceful, swift, swooping flight of scores of swallows chasing flying insects is amazing, and entertaining.  They speed and weave among each other, with never a collision.  And all the while in August and September, they drift south to warmer climes where flying insects are available while winter prevails in the north.    

     All swallows are attractive, and elegant masters of flight.  And they are entertaining in the air at all times.  

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