In the past few years, scientists have discovered a fascinating wrinkle about sexual dimorphism in harriers. It used to be thought that there were many more harrier females than males. (One article I read said the ratio was 17:1 in some parts of the world.) Everyone figured this worked for the species because harriers are the only hawk-like bird known to practice polygyny (one male mates with several females). – But recently brown harriers have been found that have look like females (although a bit smaller on average) but are males. More research is being done, but the thought now is that there have always been more harrier males than previously recognized – that some mimic females in coloration, perhaps allowing them to sneak into other males’ territories without being attacked so they can mate with the Gray Ghosts’ females.
One of the coolest things about bird research is that it keeps uncovering more and more questions! In this case: Do female harriers accept the odd-colored males? If so, why - when coloration is such an important “turn-on” in so many bird species? Are there other bird species that humans sort into male and female based on color but that nature has sorted less clearly? (Human beings love neat categories, but nature really doesn’t.)
On Nov 11, 2013, at 9:44 PM, Ian Almer Worley wrote:
> Hi Eric,
> Are you saying that "gray-ghosts" can be either male or female?
>> Hello VT Birders:
>> In response/support to Jane's statement about seeing more adult male
>> Northern Harriers in winter:
>> In general, mature males in good health (the breeders) tend to drift south
>> from their breeding territories as little as possible and return to them
>> quickly in late winter/spring to secure it once again.
>> Given that VT sits at the northern edge of the wintering range for Northern
>> Harriers, we end up seeing a higher percentage of "gray ghosts" roughly
>> We observe this with Northern Harriers because they are sexual dimorphic.
>> This holds true for other species, like Red-tailed Hawks, but there is no
>> way to sex them so it goes unnoticed. Even if you are banding a Red-tailed
>> Hawk, it gets reported to the banding lab as "sex unknown" due to
>> overlapping measurements.
>> Wintering raptors in the Champlain Valley is one of the highlights of being
>> a VT birder, at least from my perspective.
>> Good birding,
>> Eric Hynes
>> On Mon, Nov 11, 2013 at 2:42 PM, Jane Stein <[log in to unmask]> wrote:
>>> Broad-winged hawks are the only raptor that all leave for the winter. All
>>> the others are partial migrants, and our winter population here is made up
>>> of some year-round residents and some that have moved down from further
>>> north to spend the winter.
>>> Somebody with better information please correct me on this, but it's my
>>> impression that with Harriers, the females and immatures tend to migrate
>>> more, and we often end up with more adult male "grey ghosts" during the
>>> winter. I recall on one trip several years ago counting 7 adult male
>>> Harriers in and around the Dead Creek area on what was probably an up year
>>> for the vole population.
>>> On 11/11/2013 2:25 PM, Barbara Powers wrote:
>>>> A Northern Harrier was sitting in a tree in our field. It later took off
>>>> to hunt. I thought they had all left for warmer climes. Nice to see it up
>>>> Barbara Powers
>>>> Manchester Center
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