[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Bluebirds v. Cowbirds



I'm sure Jenny got lots of comments on the cowbird issue. Most of her
summary statements below are fine, but I'd like to comment or correct a
statement in (4). Cowbird chicks generally don't kill other chicks, per
se. Cowbird chicks have 2 ways of outcompeting the host chicks. 1)
Cowbird chicks have an innate behavior of often pushing other eggs or
chicks out of the nest. This is especially true if the cowbird chick
hatches first, and then it might typically push the eggs out of the nest
innately. Once chicks are in the nest, it may be a bit more difficult
for the cowbird (assuming just a single one, but sometimes there might
be two) to push the other chicks out. 2) Cowbird chicks grow faster and
often are bigger anyway than most of the host chicks. They simply
outcompete the other chicks for food. The parents put the bugs in the
widest gape they see. Thus, other chicks typically starve.

The outcome is that NORMALLY one sees ONLY a cowbird chick fledge from a
nest. This is the big problem. If the parents were to fledge one or two
of their own species along with the cowbird, we wouldn't be quite as
concerned. The nesting would be considered "successful". But, this
rarely happens.

Therefore -- by removing a cowbird egg or a cowbird chick from a nest,
you MAY WELL be saving the lives of one to 3-4 of the host species
young. Of course, perhaps 50% of more nesting attempts (without a
cowbird) fail anyway, due to predators, weather, etc. But, if you don't
remove the cowbird egg or chick, there is little chance of host chicks
fledging -- and generally, the smaller the host species (such as a
warbler), the less likely it is for any host chicks to fledge (as the
cowbird chick dwarfs a baby warbler chick).

If you are squeamish about removing a cowbird egg or chick, who says you
have to destroy the egg or chick? Maybe take the egg or chick and place
it in a pasture. Of course, no cowbird will brood the egg or feed the
chick, but at least you aren't technically taking the life of a chick or
egg.

Leaving a cowbird egg or chick in the nest will almost certainly
contribute to the "death" or failure to fledge of the host species'
young.

Harry LeGrand

Jenny Richards wrote:
> 
> Thanks again to all who wrote to help me with the issue of the cowbird chick
> in the bluebird nest.  For those that disagree with my actions, here are
> some points I would like to make:
> 
> 1.  We knew it was illegal to remove the cowbird chick from the nest before
> we did it.  Songbirds are protected, I suppose nationally. Hillsborough,
> like many townships, is a bird "sanctuary" which applies to all birds (even
> crows, Canada geese and cowbirds).  We decided to risk the legal recourse of
> our actions, if there should be any.  (Fantasies of calling expert witnesses
> to court to testify on the abhorrent behavior of brood parasites... etc.)
> Yes, we broke the law and would do it again if faced with the same
> circumstances.
> 
> 2.  Cowbirds are not native to NC and are not endangered.  According to one
> very knowledgeable gentleman on this list, they've only ranged eastward in
> the last 100 years or so.  Bluebirds are native to NC and it is only through
> human re-intervention (our first intervention reduced their native habitat)
> that they have survived as a species.  Perhaps they no longer need our help,
> but we're giving it just the same.
> 
> 3.  Cowbirds have a right to breed.  Just not in my backyard.
> 
> 4.  The entire episode was very upsetting. Damned if we do, damned if we
> don't.  We do respect animal life and do not wish to cause suffering.  For
> us, the needs of the 3 bb chicks outweighed the needs of the 1 cb chick.
> The cb chick would have killed the bb chicks eventually.  What would you do?
> Really?
> 
> Sorry to have stirred up so much controversy on the list.
> 
> Jenny Richards
> Hillsborough, NC
> jennyrichards@nc.rr.com

-- 
Harry LeGrand
NC Natural Heritage Program
DENR   Office of Conservation and Community Affairs
1615 MSC
Raleigh, NC 27699-1615
(919) 715-8687 (work)
FAX: 919-715-3085
e-mail: harry.legrand@ncmail.net