Natural Real Estate: A bird's humble abode
Marla Mertz, Marion County Conservation

When it comes to actual nesting times in our natural world, the drama of defending territories can cause quite a rumble. This is the time that some of our birds get a little ruffle in their feathers.

Eagles are fashioning their nest to lay eggs as early as February or March. Another resident bird of prey is ready to nest during the latter portion of January into February - the great horned owl. Some know this owl as the “tiger of the woods” because of its fierce attitude. The great horned is Iowa’s largest and most adaptable owl and considered Iowa’s earliest nesters, commonly laying two eggs in late January or early February. Great horned owls are monogamous (one male and one female and neither has any involvement with other nesting birds) and defend their territories beginning in late fall. These cat-like owls typically nest in large trees like cottonwoods and oaks, but use nests built by red-tailed hawks, eagles, crows, squirrels, and herons. It’s likely that great horned owls nest early due to the availability of unoccupied nests. There seems to be some discrepancy on who may be the earliest nesters in Iowa, the owl or the bald eagle.

Eagles are considered prolific nest builders, possibly building more than one nest within their territory, but that territory only holds one breeding pair. One nest may be used for a year but then another may become the chosen nest site the following year. Stick carrying and additions to a nest usually begin in late fall and continue into early spring. If you ever observe the building of an eagle’s nest, they can easily transform into a very massive piece of real estate seemingly overnight. Nests can be seven feet wide and up to ten feet deep. Some nests have weighed in as much as two tons.

Great horned owls are considered Iowa's earliest nesters. They do not build their own, but will add soft materials and pellets to larger stick nests like bald eagles or red-tailed hawks. This is was an eagle's nest the year before.
When unoccupied nests are located, it is of great opportunistic skill to adopt (or snatch) another’s nest. If you have watched the Decorah eagles online, you know when the great horned owls appear and the drama that occurs when the eagles return. An established pair of birds, whether an eagle or bluebird, do not want to return to their nest and find unwanted guests.

Natural real estate is considered priceless. The competition of some of our highly respected predators, nesting habitats and behavior seem to make or break a successful nesting season for many birds. Squirrels may build up to three nests in a tree only to use one of them as their family home. The reasoning behind this is to deter predators as to which nest they are actually in. The squirrel nests are bound to be adopted by a bird who will rework for their needs.

Barred owls and other cavity nesting birds adopt raccoon nesting trees, as the owls normally nest earlier than the nest's mammal engineer.
Screech owls adopt woodpecker holes and wood duck cavities and boxes. Barred owls adopt raccoon nesting cavities, and we could go on and on with numerous species utilizing another bird or animal’s work. Sparrows and chickadees may nest within an eagle’s nest as they are not bothered by the eagles and vice versa.

Have you seen a goose use a nest in a tree? Read about a Marion County eagle turned goose nest

  • Check out this 1986 Mutual of Omaha Wild Kingdom episode "Where Geese Nest in Trees" that shows how Canada geese in a Montana wildlife reserve adapted to using old osprey platform nests to keep their eggs safe from predators.

Quality natural real estate is not just up in a tree. Many water-loving birds will utilize beaver and muskrat houses for their nesting site.

A Canada goose incubates atop a muskrat lodge at Chichaqua. Photo from Iowa Public Radio story "Sandhill Crane Rebound On Track," photo and story by Rick Fredericksen

Osprey will build their large stick nests at the highest open area to have a 360 degree visual. When osprey return from migration, red-tailed hawks may be preparing the nest as their own.
Osprey may return from their migration from South and Central America only to find that their large stick nests are being checked out by a pair of red-tailed hawks.

Natural home building creates more nesting habitats for many species. The more diverse the habitat, the more that different species will utilize other’s humble abodes.

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Raptor Viewing Etiquette

We should all observe good raptor viewing etiquette, not only during the nesting season, but also during this time of migration. 

Remember that raptors are protected under the Migratory Bird Treaty Act and bald and golden eagles have additional protections under the Bald and Golden Eagle Protection Act.

Upcoming Programs and Opportunities

  January 21-22 Keokuk Bald Eagle Days - For more information call 1-800-383-1219 
  February 11Des Moines Parks & Recreation Bald Eagle Day, 10:00 a.m. to 3:00 p.m. at Fellowship Baptist Church, 1503 SE 6th St, Des Moines.
  February 11 Guttenberg Eagle Watch & Cabin Fever Day, Marina Visitor Center, 715 S River Park Dr., For more information call 563.252.2323 or go to 
  February 25 Effigy Mounds Bald Eagle Watch, Indoor Program at Hoffman Hall, 1600 S Wacouta Avenue, Prairie Du Chien, Outdoor viewing at Prairie DuChien Visitors Center on the River 
  February 26 Saylorville Bald Eagle Watch, 12:00 to 4:00 p.m. Stop by the Saylorville Visitor’s Center to learn about our national symbol, the bald eagle. Then venture outside to view them in their natural setting. Jester Park Lodge will host a live eagle used for education. Hourly programs start at 1 pm will give you a close look at this amazing species. 
  March 18 Spring Awakening at the Knoxville Performing Arts Center, Knoxville, Iowa, more details to come soon! 

Who am I? for the week of 23 January

So, let’s get down to it. Put on those thinking caps, grab your friends and family, and let’s play! Remember — no cheating!

  • I thrive in the open prairies and riparian woodlands,
  • I am an endangered species in Iowa,
  • I am small, but mighty,
  • I am striking in color, and
  • I am a great mouser and was a friend of farmers.
What am I? Make your guess, and then go here for the answer and more interesting facts. Did you get it right?! If not, no worries — you’ll have another chance next week!

In the news...

Check these out!

Iowa Young Birders - Check out this group formed in 2011 to help young people experience the joy and wonder of finding, seeing, and identifying birds! Check out the Iowa Young Birders website for info and field trip opportunities! <jealous!>

Developmentally-appropriate activities for early childhood learners to explore the natural world can be found at KinderNature!

Healthy and Happy Outdoors - Learn more about this Iowa Department of Natural Resources initiative here. Register with the program and record your outdoor activities in Iowa parks and recreation areas with each recorded activity a chance to win outdoor gear in a drawing.  The site also has a search feature for finding outdoor activities in Iowa.

Visit to check out a park or wildlife area you might want to explore managed by one of Iowa's 99 county conservation boards! Look here for events and activities, too!