Winter raptors, especially Northern Harriers, may be prevalent in the
Champlain Valley, but they are not in the Mad River Valley of Central
Vermont... so I was surprised to find a Harrier cruising along the North
Road in Waitsfield late this afternoon. I made no attempt to determine its
sex ;)
I have been enjoying all the information that is being passed along and
discussed about them on VTBird. Many thanks to all!
Patti
Moretown
On Tue, Nov 12, 2013 at 2:11 PM, Susan Fogleman <[log in to unmask]>wrote:
> Maeve, Kent, Ian, Jane, et al.,
>
> I think the article (from 2011) Kent may have been recalling re: female
> mimicry in male C.aeruginosus is referenced here:
>
> http://www.newscientist.com/article/dn21138-zoologger-the-only-crossdressing
> -bird-of-prey.html#.UoJvh3Avri0
>
> The research in that case did seem to indicate advantages to the females
> and
> "typical" males provided by the presence of the "faux males." Those birds
> also had an advantage in that being 'accepted' as females, they didn't get
> driven out of a territory the way a grey-coloured male would be.
>
> In a paper in the Auk from 1986, Ethan Temeles of UCDavis presents research
> indicating a prey base relationship to gender distribution in C.cyanus.
>
> The Birding magazine article by Liguori and Sullivan which Maeve mentions
> provides, IMO, quite excellent information on plumages.
>
> And NOW --- I will put in a plug for the HMANA Winter Raptor Survey. As
> Eric said, the Champlain Valley is where the action is for seeing birds of
> prey during the winter months. As some of you know, I have been conducting
> a standardized survey in the Addison area for 15 years. The data gathered
> by such surveys across the continent can help researchers' investigations
> in
> any number of areas such as the effects of climate change, human impact on
> habitats, and yes, ratios of males to females, adults to juveniles, and any
> number of other questions. While it is absolutely true that we cannot with
> certainty sex Red-tails, for example, and the challenges inherit in aging
> N.Harriers can contribute to a possibly skewed picture, some investigators
> do feel that noting size differences (i.e. a designation of "female"
> Red-tail means 'Large'; "male" = 'Small) or colour differences (i.e. brown
> vs. grey Harrier) may be useful to a future research project.
>
> All that aside, I invite you all to consider setting up and running a
> survey
> route. The more data we gather, the better, and furthermore -- it's a fun
> way to spend a winter day! Check
> http://www.hmana.org/winter-raptor-survey/
>
> for more info.
>
> Here's to Harriers! And Rough-legs and Red-tails and eagles and falcons
> and....
>
> Susan Fogleman
> Campton NH
>
> -----Original Message-----
> From: Vermont Birds [mailto:[log in to unmask]] On Behalf Of Maeve Kim
> Sent: Tuesday, November 12, 2013 9:02 AM
> To: [log in to unmask]
> Subject: Re: [VTBIRD] Northern Harrier
>
> Kent and others interested in this topic - I've been hunting through old
> birding magazines trying to find the article about male Northern Harriers
> sometimes mimicking females in color - with no success. So I'm not sure if
> the writer was describing birds in North America or elsewhere. I'll keep
> looking.
> I did find a related article that's pretty interesting, though, about color
> variations as male harriers age:
> https://aba.org/birding/birding452liguori.pdf
> Maeve
>
>
> On Nov 12, 2013, at 7:49 AM, Kent McFarland wrote:
>
> > Maeve,
> > I thought this was just for one species in Eurasia, Circus aeruginosus.
> > Is there evidence for that here in North America for the species that
> > occurs here? I didn't see anything about it in the Birds of North
> American
> > account (revised in 2011), but maybe it was very recently discovered.
> >
> > They do talk about polygyny in the Birds of North America account and say
> > it is more likely due to prey base rather than sex ratio. Our studies of
> > Bicknell's Thrush system, which is polygynandrous (a multi-male,
> > multi-female polygamous mating system), also pointed to prey base as a
> > major driver.
> >
> > I think there are a lot of examples of polygyny in hawk-like birds:
> > Galapagos Hawk comes to mind. Some species have been found to at least
> > occasionally practice it: RT Hawk, Cooper's Hawk. In Europe I think
> > something like a third of raptors are known to practice polygyny.
> >
> > A cool topic for sure! Thanks for bringing it up.
> >
> > Kent
> >
> > ____________________________
> >
> > Kent McFarland
> > Vermont Center for Ecostudies
> > PO Box 420 | Norwich, Vermont 05055
> > 802.649.1431 x2
> >
> > [image: VCE Logo] <http://www.vtecostudies.org/>
> > Visit Our Pages: [image:
> >
> Facebook]<
> http://www.facebook.com/pages/Vermont-Center-for-Ecostudies/569309
> 12454>
> > [image:
> > YouTube] <http://www.youtube.com/user/VCE14> [image:
> > Blogger]<http://vtecostudies.blogspot.com/>
> >
> >
> >
> > On Tue, Nov 12, 2013 at 7:03 AM, Maeve Kim <[log in to unmask]>
> wrote:
> >
> >> 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.)
> >>
> >> Maeve Kim
> >> Jericho Center
> >>
> >> 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?
> >>>
> >>> Thanks,
> >>>
> >>> Ian
> >>> ................................
> >>>> 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
> >>>> Nov-Mar.
> >>>>
> >>>> 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
> >>>> Hinesburg
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> 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.
> >>>>>
> >>>>> Jane
> >>>>> (Shoreham)
> >>>>>
> >>>>> 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
> >>>>>> close.
> >>>>>> Barbara Powers
> >>>>>> Manchester Center
> >>>>>>
> >>>>>>
> >>>>>> -----
> >>>>>> No virus found in this message.
> >>>>>> Checked by AVG - www.avg.com
> >>>>>> Version: 2014.0.4158 / Virus Database: 3629/6824 - Release Date:
> >> 11/10/13
> >>>>>>
> >>>>>>
> >>>>
> >>
>
|
