Talon Grappling Kites!

As I was driving to U.C. Davis yesterday evening, I saw two White-tailed Kites chasing each other above an open field just south of campus.  As I watched, they came together, grappled with each other briefly, and then locked talons and started to drop and spin.  This behavior, also called cartwheeling, is pretty famous in birds of prey.  Eagles are especially well known for talon grappling and dropping and spinning from impressive heights and only letting go just above the ground or tree tops, if then (some injuries and even fatalities have been reported).  Somewhat surprisingly, after looking into what is known about this spectacular behavior, I found very little.  The most interesting information I did find was that most interpretations of this behavior seem to wrong!  This behavior has usually been though to be associated with courtship rituals; however, Simmons and Mendelsohn (1993; see below for complete citation) reviewed accounts of this behavior from around the world that included detailed behavioral observations and found that 82% of them were actually aggressive interactions. Courtships that included this behavior have only been recorded in three species of eagle and one species of vulture and represent only 11% of accounts.  To an even lesser extent, cartwheeling may be used in play behaviors as well.

Personally, I have seen this behavior performed by Golden Eagles, Red-tailed Hawks, and Swainson’s Hawks, but this was the first time I have seen White-tailed Kites perform it.  With their bright, high contrast plumage of white, black and grey they were really quite spectacular!

Simmons, R.E. and Mendelsohn, J.M. 1993. A critical review of cartwheeling flights of raptors. Ostrich 64: 13-24

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Nesting Raptors

The birds of prey, here in Davis, are in full nest-building mode.  Yesterday I followed an adult, light morph Swainson’s Hawk that was carrying a stick and so found my first Swainson’s Hawk nest of the year being built near the top of a redwood tree on campus.  This is the exact spot where a pair nested last year and is also where I saw my first Swainson’s Hawk this year.  I have no idea if this is the same pair that held this territory last year, but it does seem likely.

Additionally, today I saw a White-tailed Kite in some grasses on the ground.  As I watched, it took off with a bundle of dead grass in its beak.  I was able to follow this bird to my first White-tailed Kite nest of the year.  This nest is in the very top of a Valley Oak out near my lab.  The tree is along a ditch that acts as a riparian corridor, although there is no water on the surface, through the otherwise agricultural land that fills the surrounding area.

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