[NatureNS] Brood parasites

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From: James Churchill <jameslchurchill@gmail.com>
Date: Tue, 9 Sep 2014 11:59:47 -0300
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hi folks,

Here is a recent paper summarizing host defense against cowbird parisitism
in North America:

HOST DEFENSES AGAINST COWBIRD (MOLOTHRUS SPP.)
PARASITISM: IMPLICATIONS FOR COWBIRD MANAGEMENT

Ornithological Monographs, 2005
http://www.biosci.missouri.edu/avianecology/courses/avianecology/readings/Peer_BD_2005.pdf

Note, this opens a pdf.

cheers,




On Tue, Sep 9, 2014 at 12:38 AM, Stephen Shaw <srshaw@dal.ca> wrote:

> An interesting question is why host species at least in some cases do not
> take countermeasures to turf out the egg(s) of the parasite.   At least in
> one case, it is not a problem of clever cryptic coloration having been used
> to evade detection.  The single cuckoo species we used to see in UK often
> lays an egg in the nest of the hedge sparrow (dunnock).  The single cuckoo
> egg is much larger than those of the dunnock, is often white with brown
> spots versus always plain bright blue for the dunnock.  Some birds, perhaps
> most, have good colour vision so there should be no problem in detecting an
> alien egg that is also twice the size.  The newly hatched cuckoo throws out
> all the dunnock's eggs, so the dunnock ends up not rearing any offspring of
> its own for that breeding cycle.  This should be a strong evolutionary
> incentive to develop a defense.
>
> Presumably there must be some disadvantage attached to developing a simple
> defense of detecting then removing an alien egg?  I could see it if the
> parasite's eggs looked very similar to those of the host -- the defending
> host bird then might remove some of its own eggs by mistake, a
> disadvantage.  At least for the UK cuckoo this is not the case: the eggs
> are easily distinguished from those of most host species'.
>
> Is there a plausible explanation for this, and is it a general
> phenomenon?  If parasitism of the dunnock by the cuckoo were a very recent
> development, it could be argued that the dunnock has not yet had time to
> evolve countermeasures, but this sounds a bit lame.   Have any N. American
> brood parasites (cowbirds?) developed eggs that mimic those of their hosts
> -- is there a general rule for this, where the UK cuckoo is an exception?
> My guess is that 97% of the folk on NatureNS are birders of some ilk, so
> someone out there must have an answer.
>
> As a related afterthought, bird books in the UK in the 50s-60s used to
> describe the nests, eggs and nesting habits of birds, not just their
> plumage.  I haven't seen this here in the Sibley, Petersen etc recent era
> in Canada/USA or I could probably have answered the cowbird question
> myself.   I presume the main (and valid) reasons are now to discourage any
> interest in egg-collecting or nest-disturbing, by simply not giving out any
> useful information?
> Steve (Hfx)
> ________________________________________
> From: naturens-owner@chebucto.ns.ca [naturens-owner@chebucto.ns.ca] on
> behalf of Randy Lauff [randy.lauff@gmail.com]
> Sent: Monday, September 8, 2014 2:03 PM
> To: NatureNS
> Subject: Re: [NatureNS] Brood parasites
>
> Our own Black-billed Cuckoo normally builds its own nest, but will
> sometimes brood parasitize other species.
>
> They avoid wiping themselves out in the same way carnivores do...too many
> carnivores, not enough prey, many carnivores starve, prey rebounds,
> carnivores increase. This is a basic explanation...there's a lot to this.
>
> Randy
>
> _________________________________
> RF Lauff
> Way in the boonies of
> Antigonish County, NS.
>
> On 8 September 2014 13:49, Gerald <naturens@zdoit.airpost.net<mailto:
> naturens@zdoit.airpost.net>> wrote:
> I hope brood parasites is the correct term for birds that lay their eggs
> in the nest of a different species.
>
> Are there such parasitic bird species who can also build their own
> nests? How do they avoid becoming so successful that they wipe out the
> hosts and thereby themselves?
>
> --
> Gerald
>
>


-- 
James Churchill
Kentville, Nova Scotia
jameslchurchill@gmail.com
(902) 681-2374

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<div dir=3D"ltr">hi folks,=A0<div><br></div><div>Here is a recent paper sum=
marizing host defense against cowbird parisitism in North America:</div><di=
v><br></div><div>HOST DEFENSES AGAINST COWBIRD (MOLOTHRUS SPP.) <br>PARASIT=
ISM: IMPLICATIONS FOR COWBIRD MANAGEMENT<br><br>Ornithological Monographs, =
2005<br><div>  </div></div><div><a href=3D"http://www.biosci.missouri.edu/a=
vianecology/courses/avianecology/readings/Peer_BD_2005.pdf">http://www.bios=
ci.missouri.edu/avianecology/courses/avianecology/readings/Peer_BD_2005.pdf=
</a><br></div><div><br></div><div>Note, this opens a pdf.</div><div><br></d=
iv><div>cheers,</div><div><br></div><div><br></div><div><br></div><div><div=
 class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Tue, Sep 9, 2014 a=
t 12:38 AM, Stephen Shaw <span dir=3D"ltr">&lt;<a href=3D"mailto:srshaw@dal=
.ca" target=3D"_blank">srshaw@dal.ca</a>&gt;</span> wrote:<br><blockquote c=
lass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left-width:1p=
x;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1=
ex">An interesting question is why host species at least in some cases do n=
ot take countermeasures to turf out the egg(s) of the parasite.=A0 =A0At le=
ast in one case, it is not a problem of clever cryptic coloration having be=
en used to evade detection.=A0 The single cuckoo species we used to see in =
UK often lays an egg in the nest of the hedge sparrow (dunnock).=A0 The sin=
gle cuckoo egg is much larger than those of the dunnock, is often white wit=
h brown spots versus always plain bright blue for the dunnock.=A0 Some bird=
s, perhaps most, have good colour vision so there should be no problem in d=
etecting an alien egg that is also twice the size.=A0 The newly hatched cuc=
koo throws out all the dunnock&#39;s eggs, so the dunnock ends up not reari=
ng any offspring of its own for that breeding cycle.=A0 This should be a st=
rong evolutionary incentive to develop a defense.<br>
<br>
Presumably there must be some disadvantage attached to developing a simple =
defense of detecting then removing an alien egg?=A0 I could see it