[tn-bird] Re: DDT Impacts on Birds
- From: "Rack Cross" <frogfarm@xxxxxxxxxxxxx>
- To: <tn-bird@xxxxxxxxxxxxx>
- Date: Wed, 28 Aug 2002 11:41:18 -0400
In response and summary,
As I mentioned in a previous post, the migration counts were those of =
Hawk Mountain and I am unable to respond at this time as to where the =
vast majority of birds counted came from. I hope to gain info such as =
Raptor Flyways via monitring this listserv and events such as the =
upcoming Bristol Bird Club Annual Hawk Migration Watch at Mendota Tower, =
Mendota, Virginia.
Bald Eagles in the US began to increase in population after they were =
placed on Endangered status. I am unaware of their Canadian level of =
protection.
For what it's worth Ian Newton, in his book "Population Ecology of =
Raptors", indicates that raptors studied in Canada (and N. Europe) =
during DDT times were found to have evidence of DDT contmination at =
"sufficient levels to affect them". I am not aware of the extent Canada =
used the the chemical, but, guess from Mr. Newton's book and your remark =
that bird recovery only began after DDT was banned in Canada in 1973, =
that it was measurable.=20
One of several bird book authors claims DDT is linked to testicular =
cancer from which he suffered and survived - I imagine his evaluation of =
the chemical is bias. Still, another claims DDT remains stable in the =
environment for "decades". While even another suggests that DDT was one =
of several things going wrong at the same time. This same author =
acknowledges the 100 million HUMAN lives saved by the use of DDT and =
actually states "...its misuse..." may have contributed to the dimise of =
bird populations.
To save HUMAN lives is good. To abuse, misuse and over use a pesticide =
like DDT and harshly impact a fragile ecology is bad.
"Til we bird again
Rack Cross
Blountville, TN
Sullivan County
=20
-----Original Message-----
From: Bob Hatcher <bhatcher@xxxxxxxx>
To: tn-bird@xxxxxxxxxxxxx <tn-bird@xxxxxxxxxxxxx>
Date: Tuesday, August 27, 2002 11:59 PM
Subject: [tn-bird] Re: DDT Impacts on Birds
Thanks, Rack, for your report of hawk increases in Pennsylvania during
1957 - 1967. If you are referring to the Hawk Mountain, PA migration
counts, wouldn't the vast majority of them have migrated from sparsely
populated areas of Canada, where the DDT impact was not nearly as great =
as
in the U.S.? Bald Eagles were never listed as Endangered, or even
Threatened, in Canada. That's why I referred to the DDT impact as, "at
least in the United States" (the lower 48).
Bob Hatcher
Brentwood, TN
******************
----- Original Message -----
From: "Rack Cross" <frogfarm@xxxxxxxxxxxxx>
To: <tn-bird@xxxxxxxxxxxxx>
Sent: Wednesday, August 28, 2002 3:16 AM
Subject: [tn-bird] Re: DDT Impacts on Birds
>
> Thanks Bob for bringing the state info to my attention. Again, I find =
=3D
> this topic a matter of intrigue and value as it relates to how we will =
=3D
> respond to the next DDT type episode.
>
> Indeed the abuse of DDT was cause for alarm, however, in PA, "For all =
=3D
> hawks, the annual count showed an increase from 9,291 in 1957 to =
20,196 =3D
> in 1967. Since it was protected by the endangered species designation =
=3D
> populations of the American Bald Eagle have increased significantly." =
=3D
> "...191 0spreys in 1946, compared to 600 in 1970." D.L. Ray, Trashing =
=3D
> the Planet. This passage also mentions an increase in Gulls along the =
=3D
> East Coast during 1941 - 1971 and that another bird of prey, the =3D
> Peregrine Falcon had been on the decline since 1890 probably due to =
=3D
> habitat loss.
>
> This is a very intresting contrast in data between Tennessee and =3D
> Pennsylvania. Further, I have had distinct pleasure of viewing at =3D
> relatively close range a Bald Eagle here at South Holston Lake, =
Bristol, =3D
> TN. in the early 90's. Perhaps I was the benefactor of the hacking =3D
> program, at any rate I am certainly opposed to any harmful event =
coming =3D
> to our raptor's or other bird groups as I am opposed to accepting =3D
> conventional wisdom as fact.
>
> "Til we bird again
>
> Rack Cross
> Blountville, TN
> Sullivan County=3D20
>
> =3D20
> -----Original Message-----
> From: Bob Hatcher <bhatcher@xxxxxxxx>
> To: TN-BIRD@xxxxxxxxxxxxx <tn-bird@xxxxxxxxxxxxx>
> Date: Tuesday, August 27, 2002 9:58 PM
> Subject: [tn-bird] DDT Impacts on Birds
>
>
> The conventional wisdom is of course that DDT builds up at higher =3D
> concentrations in birds at the top of the food chain. This includes =
the =3D
> raptors and wading birds, which suffered major declines after DDT was =
=3D
> introduced in the 1940's. Recovery only began after DDT was banned in =
=3D
> 1972 in the U.S. and in Canada in 1973, and requiring more years while =
=3D
> DDT and its derivatives dissipated from the environment. =3D20
>
> As an example, records of Reelfoot National Wildlife Refuge list 14 =
Bald =3D
> Eagle nests for Reelfoot Lake in each of 1954 and 1955 (I estimate =
that =3D
> roughly half that many nests were occupied throughout the nesting =3D
> seasons, based on Albert Ganier's report during that era). After only =
=3D
> one known STATEWIDE successful eagle nest in 1961 (at Lake Isom, 5 =
miles =3D
> south of Reelfoot Lake), there were no known fledged Bald Eagles in =
=3D
> Tennessee until 1983, when one young Bald Eagle fledged near Dover, =
=3D
> Tennessee. The release of hacked Bald Eagles (287 in Tennessee during =
=3D
> 1980 - 2003) and a few other rare raptors has sped up the recovery of =
=3D
> these species. Troy Ettel has reported that 76 young Bald Eagles have =
=3D
> been recorded in 43 Bald Eagle nests in Tennessee during 2002 =
(compared =3D
> to 60 young fledging from 36 nests in 1999). Late eagle nesting =
reports =3D
> have usually been received well past this date.
>
> The once huge heronries of Reelfoot Lake also virtually disappeared =
=3D
> during these periods. Wading birds have obviously made comebacks =
since =3D
> the late 1970's. In 1996, Dr. Fred Alsop provided the following two =
=3D
> further examples (and more), as related to the Great Blue Heron and =
=3D
> Great Egret of Tennessee:
>
> Great Blue Heron - "The breeding colonies in West Tennessee decreased =
=3D
> steadily since the early part of this century, but their decline has =
=3D
> been most dramatic from the 1950's to the mid-1970's. At Reelfoot Lake =
=3D
> in 1938 there were over 1000 active nests of 5 species of herons at =
=3D
> "Cranetown" of which over 300 belonged to the Great Blue Heron. 1959 =
was =3D
> the last big year for the colony with about 200 nests. By 1962 there =
=3D
> were only 3 nests, and the following year there was none."=3D20
>
> Great Egret - "Much reduced since the late 1930's and early 1940's in =
=3D
> Tennessee. At Reelfoot Lake in the late 1930's the bird was very =
common; =3D
> an estimate of 3500 on the lake was thought to be "conservative" and =
=3D
> there were over 650 nests. By the early 1960's this colony and others =
=3D
> had "crashed" and many were defunct. For more than a decade Great =
Egrets =3D
> were not found nesting in Tennessee. They reestablished small breeding =
=3D
> colonies in the late 1970's and these colonies continue to slowly =
grow."
>
> Since songbirds are not at the top of the food chain, it would not be =
=3D
> surprising that they would be relatively unaffected by DDT. However, =
=3D
> the evidence is very convincing that DDT had a major negative impact =
on =3D
> birds at the top of the food chain, at least in the United States. We =
=3D
> can be thankful that there are now better alternatives than DDT for =
=3D
> fighting mosquitoes and the West Nile Virus, which will be a challenge =
=3D
> at best.
>
> Bob Hatcher
> Brentwood, Tennessee
>
> =
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
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TN-Bird Net Owner: Wallace Coffey, Bristol, TN
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