Date: 7/5/18 9:14 am
From: David Sarkozi <david...>
Subject: [texbirds] Re: Eurasian collared dove population crash?
I would also caution the use of anecdotal memory as a baseline for
comparison, we don't tend to remember negative observations as much as
positive in my experience. As an example I was compiling the sighting board
checklist for Anahuac NWR. I used the 100 most reported birds from eBird by
highest percentage of reports by month, i,e, I used the month with the
highest percentage of reports to rank the top 100. American Bittern did not
make the cut, it's highest month was only 25%. I had a fellow volunteer
differ with my analysis saying her sa the bird almost every visit in
season. I asked him to count the number of visits in a row he saw the bird
to prove me wrong. After 4 negative visits he conceded the point.

Our memories of how often we see a bird are often very flawed, unless we
are counting we don't recall the negatives very well, just the positives.

On Wed, Jul 4, 2018 at 8:59 AM, Joseph Kennedy <josephkennedy36...>
wrote:

> A couple of years ago I sort of noticed that there were not as many
> collared doves around the smith point area. Did not see them crossing the
> bay and places that had large numbers had fewer. Last summer there were
> fewer but Harvey had something to do with it but did start checking other
> spots. Numbers on Bolivar were down too as well as around the house.
>
> This summer actually went and censused.
>
> A few years ago I could see 10-15 male doves do their courtship flight
> over voss and westheimer when I stopped at the red light. This year I see
> none. The several pairs at the grocery store are gone except for one pair
> and none have come by the feeder.
>
> Numbers are down maybe 90% on bolivar based on general impressions rather
> than ticked off numbers.
>
> Had trouble finding more than single pairs at smith point Monday with none
> at some points that used to have lots
>
> This population drop has occurred over 3 summers in places where I go and
> sort of count birds every week or at least very often year round. So it is
> not just a local event.
>
> Has anyone noted similar trends elsewhere. Similar population drops have
> affected other invasive species after an initial great spurt in numbers as
> predators and parasites bring the newcomer into control.
>
> The changes at home have not affected the mourning dove and white-winged
> dove numbers; if anything they are both up. Rock pigeons numbers are up
> significantly on Bolivar in the same places that I noted collared dove
> population decreases. And those two species do not compete for nesting
> sites but perhaps for food.
>
> --
> Joseph C. Kennedy
> on Buffalo Bayou in West Houston
> <Josephkennedy36...>
>



--
David Sarkozi
Houston, TX
(713) 412-4409 twitter ID dsarkozi

 
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