Date: 6/9/19 3:33 pm
From: Howery, Mark <mark.howery...>
Subject: Re: Black Vulturs
Hi Bob,
You started a very productive discussion on Black Vulture depredation! I'm
going to toss in my limited experience to build on the great information
that Jeff shared. The killing of calves by Black Vultures is rare, but
it's a real phenomenon that's been documented for nearly 50 years starting
in Texas and Florida. I first heard about it in the late 1990s, and since
1998 I've received 8 to 10 calls from ranchers/landowners who have lost
young calves (and in one case young goats) to Black Vultures. These
callers were scattered across south-central and southeastern Oklahoma -
Carter, Love, Johnston, Coal, Choctaw and McCurtain counties. As others
have said, the Black Vultures are attracted to the placenta and after-birth
when a calf is born. In some cases, the vultures will pick remnants of the
placenta off the newborn calves and in a few cases they will go as far as
to peck at the ears, eyes, nostrils, mouth, umbilical chord and anus of
calves and cause injury or death. Although I don't have any empirical
data, my belief is that the behavior of killing newborn calves is a random
event that a handful of Black Vultures learn, and then other Black Vultures
in their social group learn the behavior from watching them. I think that
is way the behavior is infrequent and scattered.

When I receive the rare calls about Black Vulture depredation, I refer the
callers to the U.S. Fish and Wildlife Service because they are the agency
with primary management authority for Black Vultures and other migratory
birds. Even though most Black Vultures are not migratory, they are
classified as migratory birds under the Migratory Bird Treaty Act (50 CFR
10.13) and fall under the jurisdiction of the federal government and not
the states. I know that the U.S. Fish and Wildlife Service and the U.S.
Department of Agriculture have been working on the Black Vulture
depredation issue for over two decades, and their work has ramped up in the
past six to eight years as the Black Vulture has expanded its range into
the Ohio River Valley.

There appear to be several factors in play that affect the frequency of
calf depredation by vultures including the access that cattle have to shrub
cover to hide their calves, and the length of exposure that cattle have had
to depredating vultures. Even through Black Vultures are very common in
Florida and Georgia, the frequency of calf deaths there is low (the USFWS
estimates that there are over 500,000 Black Vultures just in the state of
Florida). Many of the cattle raised in Florida are reared on rangeland
with abundant palmetto thickets and other forms of shrub cover where the
cows tend to hide their calves. Additionally, cows across the coastal
south, Florida and south Texas are more likely to chase away vultures when
they are calving - the assumption is that they have learned to perceive
Black Vultures as a threat. In contrast, as you move up into the upper
South and the Ohio River Valley, cattle in these places tend to be reared
in open grassy pastures (think of non-native bluegrass or fescue pastures)
where there is little to no cover for the calves, and the adult cattle have
had limited exposure to Black Vultures because Black Vultures have expanded
into those areas only within the past 20 to 25 years. Those cows tend to
ignore Black Vultures and rarely make an effort to scare them away during
the calving season. So there seem to be a few things that ranchers can do
to limit Black Vulture depredation such as moving their cattle during the
calving season into areas where there is shrub cover to hide their newborn
calves and areas where it is easier for the ranchers to monitor Black
Vulture numbers. Also, during the calving season, move cows as far away
from Black Vulture roost sites as feasible and don't let Black Vultures
develop a roost on the ranch prior to and during the calving season.

Fortunately, most ranchers coordinate the breeding and calving of their
herds so that most calves are born in a narrow window of a four to six
weeks. This synchronicity of calving makes newborn calves, placentas and
after-birth an ephemeral food source for vultures and reduces the
likelihood that Black Vultures would key in on calves and learn to kill
calves for food.

I apologize for the gross email, but I wanted to share a few things that
I've learned over the years in talking to ranchers and federal biologists.
Another issue created by Black Vultures that I've not seen in Oklahoma is
their consumption of soft plastic such as windshield wiper blades. This is
apparently a problem in urban areas along the Atlantic Coast from Virginia
to Florida, but hasn't been reported (yet) in our part of the country. I
don't know how they do it, but Black Vultures are apparently capable of
digesting some formulations of plastic and will eat this during the winter.
Mark

Mark Howery
Wildlife Diversity Biologist
Oklahoma Dept. of Wildlife Conservation
(405) 990-7259
<mark.howery...>


On Sun, Jun 9, 2019 at 8:01 AM Bob And Nancy <blnllaval...>
wrote:

> Thanks to everyone for the information. It was a big help. It’s good to
> know that actual research has been done although many of the words used
> were not in my vocabulary.
>
> Bob Laval
> Heavener
>
> Sent from my iPad
>
> On Jun 8, 2019, at 9:04 PM, J.B. Tibbits <jeff_osu...> wrote:
>
> I've heard of "Mexican Buzzards" as well. As with coyotes, it does happen
> but not as frequent as described. I suspect they're more interested in the
> afterbirth, and any predation is rare/opportunistic.
>
>
> https://www.researchgate.net/publication/231859968_The_presence_of_black_vultures_at_the_calving_sites_and_its_effects_on_cows'_and_calves'_behaviour_immediately_following_parturition
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.researchgate.net_publication_231859968-5FThe-5Fpresence-5Fof-5Fblack-5Fvultures-5Fat-5Fthe-5Fcalving-5Fsites-5Fand-5Fits-5Feffects-5Fon-5Fcows-27-5Fand-5Fcalves-27-5Fbehaviour-5Fimmediately-5Ffollowing-5Fparturition&d=DwMF-g&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=WtcHdIgfPcd5duugjo56RvrWKXWbcpxsIgrqUhahxv0&m=uj09tYlLrg4eBMHJ3b7256QRigYRfzcxcg6jnndXwWY&s=M2f3c_ITxp0SvJS1RD4fmJAm8KRgFmrOwD3Xy98G-A4&e=>
>
> Abstract:
>
> "Black vultures (Coragyps atratus) are often present near calving sites,
> and under this situation they may play a positive role by removing animal
> carcasses and afterbirth or a negative role by attacking neonate calves or
> disturbing cow-calf behaviours following parturition. Cow-calf behaviour
> was recorded over a 4-year study period from a total of 300 births
> involving 200 Nellore, 54 Guzerat, 20 Gyr and 26 Caracu cows. The calving
> site in relation to the location of the herd, considering cow-calf pairs
> within, close or distant to the herd, the presence of vultures and the
> behaviour of cows and calves were recorded instantaneously, at 5-min
> interval. On average, vultures were present at 80% of the calving sites.
> The frequency of vultures present at calving sites was dependent on the
> years for the Nellore herd, increasing from 1998 to 2003. When vultures
> were present, the time that the cow was in contact with its calf decreased,
> and the percentage of time that the cow was standing still increased.
> Vultures were observed pecking cows and their neonates during 34.1% of all
> recordings. However, in only two cases pecking injuries were actually
> observed on calves that were noted to be very weak. The preliminary results
> suggest that although black vultures cannot be characterized as a predator
> of neonate calves, they sometimes attack neonate calves and their presence
> near the calving sites alter the behaviours of cows and calves."
>
> ------------------------------
> *From:* okbirds <OKBIRDS...> on behalf of Steve Schafer <
> <steve...>
> *Sent:* Saturday, June 8, 2019 2:35 PM
> *To:* <OKBIRDS...>
> *Subject:* Re: [OKBIRDS] Black Vulturs
>
> Yes, Black Vultures are known to attack newborn livestock: calves, lambs,
> etc. It's uncommon, but it does occur.
>
> -Steve
>
> ------------------------------
> *From:* okbirds <OKBIRDS...> on behalf of Bob and Nancy <
> <blnllaval...>
> *Sent:* Saturday, June 8, 2019 3:07 PM
> *To:* <OKBIRDS...>
> *Subject:* [OKBIRDS] Black Vulturs
>
> I drink coffee with a bunch of guys every morning, composed of ranchers,
> and chicken farmers and others. I heard something yesterday I have never
> head before. One of the ranchers was cussing *Mexican Buzzards*. I
> asked him what he was talking about. He described Black Vultures. He
> said they are killing some of his calf's. He described an action by the
> Vultures that he has observed more than once. The vultures swoop down on a
> live new calf laying on the ground and peck the eyes out if they catch the
> mother too far away. The calf of course starves to death and the vultures
> feast. Others around the table agreed. They say the BVs are new to the
> area at least in large numbers. I see a few every summer but I’m not really
> out on the ranches. Has anyone heard of this habit?
> Bob LaVal
> 20367 Pine Mtn. LP
> Heavener, OK 74937
> Phone: 918-653-7921
>
>

 
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