Bald Eagles defend nest sites

PHOTO BY GARRY BRANDENBURG It is that time of year again for Bald Eagles to be aggressively defending and or selecting new nest sites. After the 2018 nesting season, Iowa had 377 active Bald Eagle territories. And volunteer citizen scientists who monitored active eagle nests reported data that told biologists that 67 percent of the nests were successful and a statewide average of 1.38 young were produced per nest. A post nesting season eagle survey for 2018 had a total of 3,921 eagles counted. I do not have the 2019 mid-winter eagle count numbers at this time, however, one can assume safely that close to 4,000 bald eagles were calling Iowa their winter home. Marshall County’s known bald eagle nest sites, about 10, probably more, have activity on them right now. This is good news for this very big raptor. Look for them anytime you are out and about.

BALD EAGLES (Haliaeetus leucocephalus) are quite common in central Iowa now. It wasn’t always that way 20 or 30 years ago. This magnificent raptor has made a come back from its former threatened status. While Marshall County residents might see an eagle or two in any farm field, open water locations add to the likelihood of seeing eagles either flying or perched on a tree branch near open water. Since fish are their primary food source, any swimming fish near the surface of a river, stream or lake might end up as dinner for the eagle.

Each year surveys to observe eagles are conducted on standard routes. The bottom line from this survey method tells of a stable to slightly expanding bald eagle population. And locally, more than one landowner tells of seeing eagle pair activity on nests they routinely have chances to observe.

Iowa officials have seen enough evidence and data to have the Bald Eagle removed in 2009 from ‘threatened’ status and placed in a new category of ‘Special Concern.’ Annual counts have continued to add data supporting this action.

Training for anyone desiring to add local information of eagles may signup as a volunteer. Online video information is available at www.iowadnr.gov/vwmp/ to become a volunteer. Another option is to attend a workshop during March and April at various locations across Iowa. After training, volunteers are assigned to one or several nests in their area to monitor.

If 377 active territories in 2018 had an average of 1.38 chicks per nest, then an estimated 412 new eagles were produced in Iowa. With 377 territories classified as active, the adult population of breeding Bald Eagles at a minimum is 754. This number is four times the original goal set for Iowa when the eagle recovery plan was initiated in 1983.

The trend line is going up and the curve is flattening somewhat now which indicates eagles may be close to carrying capacity for Iowa. Minnesota has more habitat and more lakes so their 1,000 plus territories for eagles is understandable. Iowa is not Minnesota, but we should also know that important winter habitat is offered here and Iowa Bald Eagles do add significant numbers to the national total.

The wingspan of Bald Eagles is anywhere from six to seven and one half feet. Male and female adults look alike with the female being slightly larger body size. They stand three to three and one half feet tall. Weight is eight to 15 pounds. Eagle eyes are at minimum five to six times more powerful and acute than human eyes. Fish are the primary food, but carrion will work. Waterfowl migrating each spring may become injured or ill for which eagles will notice and take advantage of. This is part of Mother Nature’s food chain of survival.

Bald Eagle nests may grow each year as new material is added. Over time a nest can become seven feet in diameter and 12 feet deep. It is estimated the nest alone can weigh over two tons. One to three eggs are laid each late winter. Incubation takes 35 to 40 days. Young eagles may take their first flight seventy-five days after hatching. Young eagle plumage will remain dark brown for at least four years with signs of white head and while tail feather emergence at adulthood by year five. Feather molting for eagles is a continuous process so at no time is an eagle flightless.

To learn more about possibly becoming a Bald Eagle volunteer, you may contact the Iowa Department of Natural Resources Boone Research Station at 1436 255th St., Boone, Iowa, 50036. You may also call them at 515-432-2823 or send a note via computer to vwmp@dnr.iowa.gov.

BOBCATS are secretive, stealthy and rarely seen. Unless you happen to be in the right place at the right time. One cannot discount good luck as a factor. That is what happened this week for one Marshall County landowner. While driving his side-by-side ATV, he at first spotted a small deer along a trail and not too far away, a bobcat was on the same trail. Enough time was available for a good look at the animal to note is was indeed a bobcat.

Bobcat numbers in southern Iowa and all of Missouri have been known for many decades. And it has been known that bobcat populations are slowly expanding northward as new range is filled in wherever the bobcat desires to call home.

“We are seeing them fill in areas of good habitat throughout the state from the south and in a northward direction,” Vince Evelsizer, DNR furbearer biologist, said.

Bobcats are a native species that had been in low numbers decades ago. Now they have increased in numbers, on their own and have proven to be a wildlife success story. What Iowa DNR regulations did was hold down the legal taking of bobcats for a long time. Now trapping for this species is limited to three per year in the southern three tiers of Iowa counties and one per year along the Missouri River corridor and parts of east central Iowa. There is no legal taking allowed in most of the state.

Bobcats are one of three wildcats. The others are the lynx and mountain lion (cougar). Bobcats are the only species with established populations. Lynx are a far north land creature specializing in taking snowshoe hares in Canada and Alaska. The mountain lion is noted for its passing through Iowa where trail cameras occasionally document this big cat passing by.

A bobcat adult has a body only three feet long and it has a short tail no longer than 10 inches. Adults weigh 20 to 30 pounds. Fur color is a mottled gray-brown spotted arrangement with lighter belly fur. The diet of a bobcat is 95 percent rabbits, mice, voles and squirrels. Life span in average is three to five years. A really old bobcat might reach 10 years.

Did you know….that during 2019, Iowa residents purchased 195,509 annual fishing licenses? As one of several options, 44,102 folks purchased fishing, hunting and habitat combination licenses. Hunting licenses to the tune of 66,196 covered those wanting to hunt whereby the habitat fee was included. Migratory game bird licenses numbered 23,373. For large game animals, deer, 51,900 archery tags were sold. For first gun deer the number was 43,380 and second gun deer came in at 44,921. Late muzzleloader deer was 20,188. Spring turkey licenses for archers was 5,257 and gun turkey sales for all four segments of turkey hunting was about 29,400.


Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at PO Box 96,

Albion, IA 50005.


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