Ants as Bird Fuel
Common Nighthawk
Credit: Tom Vezo
Every year as the hot and humid days of summer ease into the dry warm days of early fall, the nighthawks appear. In the eastern U.S. at that point in the evening when the setting sun lights up the landscape, there appears in the sky dozens sometimes even hundreds of large silent, dark, knife-winged birds. They fly quickly and erratically with sudden twists and turns. When one comes close enough you may see the white patch in the wing.
Common Nighthawks have virtually completely disappeared as nesters across the eastern U.S. and these migrants that pass through in Augusts and early September must certainly be coming from the Boreal. Although I cannot prove it, I suspect that the timing of the southward migration may be tied to an annual seasonally abundant food source – flying ants. At this time of year on dry warm days, ant colonies send out their drones and queens for their pioneering attempts to found new ant colonies. The number of flying ants must be mind boggling across the northeast U.S. through August and September. I can’t really imagine how abundant they must be but you see them everywhere. The last summer day we went swimming in our favorite lake, the water’s surface was covered with millions of them – the fish were going crazy with the feast – that had been blown into the water on their mating flight. These millions of ants could be the perfect food source for those nighthawks to use to fatten-up and power their long journey to South America where they seemingly disappear into the wilds of the Boreal’s sister, the Amazon Basin.
Flying Ant
Credit: Jeff Wells
Here’s a video I found on YouTube of a Common Nighthawk darting around the sky in a similar fashion. You can tell how quick the bird is twisting and turning based on the camera-holder’s difficulty in keeping it in the frame!
October 27th, 2009 at 1:43 pm
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November 2nd, 2009 at 8:27 pm
Hello All,
I’ve made similar observations for the past few years at Long Point, Ontario. I would however be reluctant to suggest that CONI’s are entirely dependent on this food source during migration. The migration window for CONI’s can be quite broad emcompassing times well before and after ant dispersals. I’m also wondering if we’re just observing more CONI’s during these ‘ant-nights’ as the nighthawks will probably be more apt to foraging earlier on these evenings when we’re more likely to observe them. There is likely a suite of factors influencing the timing of CONI migration. A sidenote is that Ring-billed Gulls also love the ants.
Stu
November 3rd, 2009 at 6:15 pm
Yes, I’ve noticed Ring-bills really focusing in on the ants in late summer and ealy fall. They have that characteristic awkward stall-out flapping as they try to snatch the flying ants. There have to be lots of things that affect the timing of their migration of course just as there are in species like Red Knots and other shorebirds that seem to rely so heavily on the timing of an abundance of horseshoe crab eggs. I wonder how much energy a bird can get from flying ants and whether the ants have metabolically difficult compounds in them as well?
Jeff
August 18th, 2010 at 9:20 pm
Down here on the mid coast of Maine we see the Laughing gulls and some Bonaparte’s loving the ants, too. Big flocks of both types of birds gather to munch and are pretty impressive to watch.