Thursday, July 28, 2011

Northern Harrier

Only my second sighting of an adult male Northern Harrier, this raptor approached me from behind, just to my left, as I started my walk around Fernhill Lake last Saturday. I was lucky that I happened to look back and saw it coming before it had passed me, so I was able to get some decent pictures of it.
I see female and young Northern Harriers fairly regularly, but few males. This topic was brought up on the Portland Area Birds Google Group back in January. Group owner Greg Gillson had this to say:

"Here's what I found on a web search....

Males breed with more than one female and the sex ratio is not even, according to multiple studies. There were 1.8 females for every 1 male on average in one frequently-quoted study.
There was a similar nesting success, something like 1.8 young fledging per nest on average.
So, females and juveniles ("brown" harriers) outnumber males in early winter by about 3.25 to 1. There was about a 60% mortality rate of first-year birds.
Complicating the apparent ratio, males may not winter in the same locations as female and juveniles. Males are smaller than females and may migrate farther south in winter. Age/sex groups do not migrate at the same time. Adults precede juveniles back to the breeding territory and males precede females."

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