1.11.16

Sky Dancing

Like its northern counterpart, this southern member of the circus genus - the Cinereous Harrier - fills the classic harrier niche over the grasslands and steppes of the Southern Cone, with a disjunct population in the northern Andes.

For the couple of years I worked out of El Calafate I spent many days (either alone or finding birds for clients) at the small Laguna Nimez nature reserve sandwiched between the town and the vast glacial Lago Argentino.

Here, I got to know one pair of harriers very well, watching their courtship and the eventual rearing of a young harrier.

During the courtship period the birds were very territorial, with both male and female occasionally dive-bombing the heads of any humans that crossed their territory. A bird bearing down on you is fun when it's an arctic tern, but kind of scary when it's a large harrier.  One of my clients even lost a hat.


Getting ready to strafe someone's head - talons out, eyes fixed. 

A big part of harrier courtship is the swapping of gifts - usually a prey item, like a small passerine.

Here you can just see the 'gift' - a small passerine, which I never figured out to species - in the talons of the harrier as she comes over to investigate my presence:




The gift exchange involves some spectacular aerobatics, as one bird twists upside down to make the catch. In weeks of watching, I never saw a drop. Interestingly over the days I watched them, they seemed to retain the same 'gift' as it was passed between the pair, and always carried it in the same talon! Presumably at some point it was 'refreshed' to avoid the risk of parasites.







Here two females court in the air above the marshland. I never figured out why same sex courtship was so prevalent in this location. Worldwide, harriers are pretty notorious for their polygyny (and occasional accounts of polyandry have been recorded in northern hemisphere harriers), as are many marshland species of other avian families, but I never found much documentation of same-sex courtship within harriers, polygynous or otherwise.

Moreover, Simmons, in his Harrier monograph, suggests that polygyny is rare in southern hemisphere taxa:





The female sits in  a senecio bush - about as tall a vantage point as it's possible 
to gain in this xerophytic steppeland.



Most harriers share the owl-like facial disk and the cinereous is no exception. Presumably its parabolic function is a similar adaptation to aural hunting that owls have expressed even further.




The female brings in nesting material 





Hunting involves a technique that is well known in both northern and hen harriers, the tapping of the grass with the wingtips, to flush prey. Here the female exhibits the classic drop-like-a-rock technique.





The sadly defunct quarterly 'coffee table' magazine, Bird Art & Photography, ran some of my harrier shots, (alongside some much better Condor shots of my brother's)...

The position of cinereous harrier in the monophyletic harrier clade also reveals a lot about our own northern harrier.

One reason the NACC should accept the split between hen harrier and northern harrier is that based on mtDNA evidence (although not enough base pairs were tested according to some of the NACC committee) the cinereous harrier is sister to the northern harrier, and closer to it than the purportedly 'conspecific' hen harrier of the western palearctic.

Even the BOU recognised this split earlier in 2016 - which I was very happy about as my upland farm in the UK's Peak National Park is one of the only sites in the UK where the heavily persecuted hen harrier can still be seen!


A male harrier shows his displeasure at the chimango caracara flying through his territory



The harriers carry on courting as the sun sets over Patagonia. 

No comments:

Post a Comment

About Me

My photo
NYC, Buxton, Buenos Aires
I work in NYC and own a wildlife and wilderness agency specializing in the southern cone of South America. I still do some guiding down there, especially looking for Fuegian and Patagonian avifauna. I'm particularly interested in the wintering ecology of neotropical migrants, and in avian biogeography in general. You can follow me at - @domhall And find me at - AventuraArgentina.com