They arrived, they stayed awhile and then they left.
Bobwhites, one of our favorite birds because
of their flight characteristics and especially their call, have not been heard
this year on the ranch.
All North American bobwhites
(Corvus Virginiana) are catalogued in 23 subspecies and these subspecies
are divided into 4 groups. Three of the
four groups (Masked, Grayson’s, and Black Breasted) live in central and south
America and the fourth group , the one to which our local bird belongs is the Eastern
Group. In Texas, of the 23 subspecies,
we have two different bobwhites, the
subspecies Texanus and the Taylori. It takes an expert to tell all these
subspecies apart as they are so similar in appearance.
The Texanus sub
specie is our local bird, its range is from Central Texas south well into
Mexico. The Taylori sub specie ranges from Central Texas up into the
central plains of the states to the north.
The bobwhite has several
habits which are unique. They are insect and seed eaters, they group into coveys, they tend to be monogamous, and
they fly with a wild beat of the wings when flushed from their roosts producing
a sound that is memorable only second to the sound of a rattlesnake.
They roost on the ground, where
they form a circle of birds all facing outward from the center of the circle
and thus give the impression when flushed, that they all fly in different
directions and for the first instant they do because of this roosting
arrangement. They do this for protection as they have several natural
enemies---like hawks, owls, coyotes and of course hunters.
Ranchers in Texas,
particularly in the high plains and in south Texas find that leasing their land
to hunting quail brings in more profit than running cattle on the same
land----that’s not easy to pin down as it may be the difference between two low
numbers. Nevertheless, hunting bobwhite
in Texas is a big thing and brings in a lot of associated revenue and taxes.
Bobwhites nest in the
springtime and find the best spot to nest at the base of a clump of a typical
Texas bunch grass, where the top of the bunch grass may be 18 to 20 inches tall
providing seclusion and some shade at parts of the day. Heavy underbrush is not their favorite
habitat, grassland with some scattered brush is their preferred habitat.
The Bobwhite has been the
focus of research for the last 80 years, probably due to the importance as a
game bird and a bird that could be
raised for food. Squab farms are common, especially in the northern states.
In the 1940s, researchers
found that Vitamin A is an important component in the food they eat, and the
source of Vitamin A for the Bobwhite is green vegetation. Typically, 70 % of the food for a bobwhite is
seed, but during breeding season, that changes to include more insects, and
green vegetation to achieve their Vitamin A requirements. In turn, Vitamin A was found to be critical
to egg production and the overall health of the bird. Low Vitamin A could lead to short life span
but in most cases, the bird succumbed to predators because low Vitamin A caused
low energy, poor eyesight, and a general inability to escape predation. Related
to this dietary study was that landowners attempt to supply food for the
bobwhite to augment natural foods had little effect on the population of the
species. Almost all the programs to help
the bobwhite produced little positive results. They apparently know the difference between natural food and artificial food.
In the 1970s, studies were
conducted on the need for caloric intake at different ambient temperatures;
this study found that egg production was peaked at temperatures between 70 and
77 degrees F. Out of this study came the
bonus information that showed that Bobwhites can tolerate heat, but just so
much heat. For females, that temperature
is about 107 degrees F, males a few degrees higher. Sustained temperatures above these levels and the birds succomb.
In our area, high
temperatures usually mean low water levels in the soil—whatever rain we may get
in the hot weather months evaporates quickly.
Bobwhites and for that matter, all the members of the quail family are known
for their wild fluctuations in population correlating with rainfall. An intuitive
conclusion is that high rainfall means more green vegetation as food (Vitamin
A) and lower temperatures, both of which favor reproduction.
Populations of bobwhite
appear to be decreasing by about 2-3 % per year from the best estimated of bird
counts and harvest counts from hunting.
This decline in population has been linked to several factors, some old
natural ones and some newly discovered.
Regarding the established
factors affecting population, all the known predators factor into the equation,
but skunks and fire ants may be at the top of that list. Raccoons follow as a distant third.
But there are new concerns for the health of the bobwhites; not new but seemingly found more often in recent years. There is a parasite
that is picked up by the bobwhite from eating grasshoppers. Due to the heat and the drought, our
grasshopper population has burgeoned this last year and again this year. The parasite that is picked up is a thread worm
that escapes from the bird crop and migrates to the nasal passages and
eventually into the eyes. These thread
worms have been known to biologists for decades, but it appears that the
infestation has grown to epidemic status in some parts of Texas. The thread worms are destructive, destroying
vision long before it kills the bird.
Hunters have reported birds that fly into obstacles upon being flushed
and even birds with open eye sockets. A
medicine has been developed for adding to food supplies, but the problem is
getting the birds to eat the medicated food.
The outlook for this problem is not good.
Nest success is another problem with
Bobwhites. During average conditions of
temperature and water availability, the success of the nest ranges around 28 %
in most studies. The nest sizes are
large though, offsetting this low nest success level. About 12 eggs are the normal nest size, so
when the nest is successful, there are many baby quail. Studies show that the skunk is the most
probable cause of nest destruction.
If seeds are the main food
for the bobwhite, what seeds are preferred?
Analysis of crops from birds across Texas show that their diet consists
of a lot of different grass seeds, but there are some that are obviously preferred. Here are a few: Sorghum, both the naturalized plants and those planted for food production are a favorite of
the bobwhite. Among the grasses, such as
the rescue grass, the paspalum and those grasses with seed heads like sorghum
are favorites of the bobwhite.
From all these studies of natural foods for the
bobwhite, the data show that most of the favorite foods grow most predominantly
in the eastern part of the state or the southern part of the state, leaving the
hill country short of natural food for the bobwhite.
So, what about our brief
encounter with the bobwhites? The
intuitive conclusion is that they did not find enough food and their time here
was during those years when we had slightly higher than normal summer temperatures and lower rainfall. Whether they died off or migrated to other
areas is not known, but it could be presumed they did not reproduce well and
the died out.
All this reminds me of my
younger days of hunting ring-necked pheasants on my uncles farm in Hudsonville,
Michigan. The whole area was farming
country then and most farms planted corn both for the corn and the corn
plant. The corn was saved for the
chickens, and the corn plant, while still green was chopped up and put into
silos for the winter feed of the cows.
But while the corn was still in the field, the pheasants not only ate
the corn, but they found it easy to run down the corn rows to hide from
whatever came along. Every 20 acre field
had several cock pheasants. Then,
progress came to the area and the farmers disappeared and so did the corn and
so did the pheasants. It would be a challenge to find one pheasant there today.
All this shows that wild animals, and plants for that matter, live where they can thrive, and when those conditions turn negative, they leave or die.
