Hi Evan
These would almost certainly be Welcome Swallows.
As well as being excellent flyers at altitude, these birds are excellent at
employing "ground effect" with their rapid low level flights across playing
fields. Of interest to note is that they are clearly more actively snapping up
insects when the sun is behind them. With the sun behind them, their shadow runs
along the ground before them. I have frequently noted this and have
concluded that, like the Willie Wagtail*, they may well actively employ
their shadow as a means of disturbing
insects into motion before them.
Swifts may swoop low now and again, but
definitely favour significantly greater altitudes than 10cm above playing
field surfaces.
*Willie Wagtails use the shadows cast by their
wings and tails to disturb potential prey into flight, which they then snap up.
(I've noted this in my own studies for Uni as well as in another paper or
two by other researchers. I can provide if you're interested.) If you've
ever run across a field in the company of Willie Wagtails in the morning or
afternoon, when your shadow is a little longer, they will freqently work
alongside your shadow, right on its edge. I have even noticed "Willies"
following the front line of the shadow cast by my car along the curb and eagerly
snapping up prey which the shadow disturbed. . . Fanstastic stuff!
Ricki Coughlan Lyrebird
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