Wildlife in abundance

PHOTOS BY GARRY BRANDENBURG — Wildlife populations in late summer may be at peak numbers for a while, since this time of abundance makes finding food, escape cover and freedom from predators the least of their concerns. Green forage plants for deer or rabbits are everywhere. Life is easy. Finding places to slip into the shadows and not be detected by predators is also easy. Summer’s warm air temperatures mean struggles against bitter winter cold air is still a long way away. Summer food and cover allows these critters, and many other species, to build up fat reserves and overall good body condition prior to the restrictions of the coming fall and winter seasons. Upland wildlife survey count data should be published by Iowa’s DNR biologists by this time next month.

How many wild critters are there in Iowa? Well, it is impossible to count each individual bird species, insect, reptile, amphibian, mammal, or invertebrate. Biologists focus on habitats where these animals live and are specifically adapted to.

To a huge extent, if the habitat is of adequate size and well managed, and gets cooperation from Mother Nature in the form of timely rains and no big storms, then survival is made easier.

Biologists use specific programs, indexes and their knowledge of habitats to make population estimates.

Survey data adds specific observations. These “count” methods are used to determine trends for each species or upland bird or mammal, those species that are most easily observed. Data year after year can be compiled to make very reasonable quantifications.

At fisheries, biologists can also place tiny electronic transmitters in fish and follow these finny animals in rivers or lakes. Other tiny electronics can be placed on insects to follow them.

Birds can carry light weight signaling devices to report their positions anywhere on earth. Deer can carry neck collars to send signals to waiting ground or air based receivers. Data collection is what biologists are after.

Once the data is accumulated, interpretation and analysis are next. This is not just a willy nilly hodge podge of confusing numbers. The data has to have meaning and purpose that can be critically reviewed over long time frames. Behind the scenes work in offices and laboratories can make sense of raw data and raw numbers gathered from the field.

The result will be trend lines showing, for example, fairly accurate estimates of waterfowl numbers by species prior to the fall migration. Hunting season start dates, end dates and bag limits can be adjusted accordingly. Another example, in this instance for white-tailed deer, night time spot light surveys, winter post hunt aerial counts, fall hunter confirmation reports, and knowledge of habitat regions across Iowa all add to the data.

The issue of the land’s carrying capacity is often brought up. Carrying capacity is the term used by scientists to delineate how many wild critters of all shapes and sizes could make a living in a particular habitat. Since soil types, habitat zones, and land uses vary so widely across Iowa, there are no simple and easy answers.

However, by the time a large overall picture emerges, one can get a grip on how many animals are out there. From that, excess numbers can be determined and reduction methods implemented.

Example: How many deer could Iowa lands reasonably handle if unlimited growth was the official policy? The answer: a lot more than we now have by a factor of at least 5!

Before anyone gets too knee jerky about allowing deer numbers to be five times higher than now, that potential is well understood and known to biologists. And because biologists also know what the land can produce in the spring, summer and fall may not be even close to what the winter season will allow.

Thus for game animals, hunters play a vital conservation management role to have a harvest, or off-take, of a certain percentage, varied by each habitat region, so that the overall breeding and remaining population is still adequate when the end of one winter season happens, and a new spring season begins the following year.

There is also the political balance, or “societal carrying capacity” that boils down to what people will tolerate. I can assure you that allowing too many deer to prosper is an end game that nobody really wants to see. So rather than have huge swings of ups and downs in a wildlife population, a more even and much milder series of ups and downs is much preferred.

Landowners who raise livestock know the limits of their lands. Too many cattle for instance can graze pastures into unhealthy conditions for the grasses. Dry conditions as recently experienced means controlling the number of animals at any one time in any one location so as not to harm the land itself. I have seen this numerous times with farmer/rancher friends where a year with abundant rains meant good pasture production.

Total animal units theoretically could be increased. Then when a drier than normal series of years comes into the cycle, there will be too many cattle mouths to feed compared to past abundant years. The carrying capacity of the land is always a moving target even for domestic livestock. Wildlife carrying capacity works the same way.


My other featured creature for today is a Cottontail Rabbit, (Sylvilagus floridanus). The first part of this scientific name refers to the Latin and Greek origin meaning wood hare.

Sylva refers to wood. Lagos refers to animals called hares. The second part of the name floridanus refers to the area where the animal was first described and collected.

There are additional common names attached to rabbits. Eastern Cottontail Rabbit is the primary rabbit we see locally. Its name comes in part from the white fluffy ball of fur of its short tail.

Just to the west of Iowa one can find White-tailed Jackrabbits. A few of this species may still exist in portions of northwest Iowa in large complexes of prairie grasslands. Further to the southwest in desert environments live Black-tailed Jackrabbits.

Pika are smaller bodied rabbit-like mammals with very tiny ears. They live in high mountain rocky talus slopes. Rabbits have two pairs of upper incisors. Long ears are our first clue

and medium body shape with large rear legs are another. The fact the rabbits can and do run fast adds to our identification.

Fast running capability is essential since rabbit populations can grow very fast, and predators from the sky (hawks, eagles and owls) and predators on the ground (foxes, coyotes, snakes) take due diligence of this as food for sustaining their own lives. Note the large bulging eyes of the rabbit in today’s image. These eyes allow for detecting movements in almost a 360 degree view ahead, behind, above and below. This adaptation is critical to help avoid predators.

Cottontails eat vegetation that varies depending upon the season of the year. Leaves, stems and flowers will work. Fruits and berries come into play later in the fall and winter. The bark of woody plants may be utilized in hard times of deep winter.

Gardeners know that a rabbit fence may be essential to keep these mammals away from growing vegetables. After a fresh winter show covers the ground, people notice rabbit tracks whereby the animals the night before explored all kinds of places as they searched for food. Snow leaves evidence as rabbit footstep depressions.


Duck hunters who like to pursue fast flying small ducks called teal will get their chance soon. The date is Sept. 1 for the starter. The U.S. Fish and Wildlife Service monitors teal populations in all breeding grounds. If and when populations are very abundant, the service can allow for hunting early migrating teal during a 16 day time frame in early September.

Such is the case in 2022. Orrin Jones, state waterfowl biologist, notes that breeding conditions this past year in the Dakotas, Minnesota and prairie Canada were favorable. Therefore, there will be a good supply of teal moving into Iowa from mid to late August.

A change in weather patterns north of us can stimulate teal to move out ahead of a cold front. Overnight a once open water wetland can have lots of teal on it the next morning. Nighttime migrations are typical.

The hunting season is open only for teal, blue-winged or green-winged. Proper identification is essential. Another difference in hunting is the time frame — only from sunrise to sunset. A state migratory game bird fee and federal duck stamp are also required in addition to a regular

hunting license.

Another fall season begins Sept. 1, and that is for doves. These prolific birds are very numerous. Sunflower fields, or cut hay fields may attract either mourning doves or Eurasian collared doves.

Dove hunting times are one half hour before sunrise to sunset. Plugs in shotguns must be used to limit shells to three. Non-toxic shots may be required north of I-80. Hunters must also pre-register with HIP (Hunter Information Program) via the website link at www.iowadnr.gov/waterfowl or at www.gooutdoorsiowa.com. Dove limits per day are 15 with a possession limit of 30.


Hunter Safety classes, the in person type of classroom setting, will be held at the Izaak Walton League on Aug. 25, a Thursday evening from 6 to 9 p.m. and the following Saturday from 8 a.m. until 4 p.m. Youth ages 12 or older are encouraged to attend, take the class and pass the exam.

This certification is required before a hunting license can be purchased, and it is a one time thing, good for life and honored by all other states. Sign up for hunter safety must be done online at www.iowadnr.gov/huntered.


Garry Brandenburg is the retired director of the Marshall County Conservation Board. He is a graduate of Iowa State University with a BS degree in Fish & Wildlife Biology.


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