×

White Pelicans make impressive flights

PHOTOS BY GARRY BRANDENBURG — White pelicans are huge white flyers with black wingtips. They are graceful flyers as they circle in large flocks on spring thermal updrafts. On water, the flock will work as a unit to move fishes into shallow areas, then simultaneously poke their heads below the water surface to try capturing fish into their long pouched lower bill. White pelicans can show up mid-April on their journey north toward big lake country. Locally, white pelicans may show up at Green Castle, Sand Lake, Hendrickson Marsh, Otter Creek Marsh, Timmons Grove, Arney Bend or even Riverside Cemetery.

White pelicans (pelecanus erythrorhynchos) will soon be a common sighting, along with other migratory waterfowl, as their large flocks grace the skyline. A huge flock of these birds with eight foot wing spans will readily demonstrate an incredible steadiness to make it appear the soaring/gliding is simple, easy and fun. The air is their pathway from one water body to another as they search out resting sites and food sources.

Fun facts about pelicans tell of their group behavior in flight and on the water. There are a lot of eyes to watch for predators and look for places to find rest and food. This species scoops up small fishes, salamanders, crayfish and tadpoles. Once inside the bill pouch, the head is tilted back to facilitate swallowing.

They never carry food in their mouth and go flying. Foods are swallowed first, then flight happens. Another note of fact: it takes a pelican pair time to gather 150 pounds of food to bring to their newly hatched chicks before those young birds will become self-supporting. Only one young in the nest of two is likely to survive.

Sibling rivalry will have one chick dominating for food and space, usually resulting in the early death of the weaker hatchling. The young can swim if they can get to water. As they grow larger, they will use their wings and feet to “run” across the water surface. Eventually, the wing feathers will be sufficient in nine to 10 weeks to allow the young birds to fly.

————

Wood ducks have returned. This is one of a few cavity nesting ducks that prefer to seek out and find hollow trees to call home for the nesting season. Woodies may also take readily to man-made wood duck houses. In either case, once a pair has decided to call a tree or nest box home, it will be the focus of their attention as nest building, egg laying and young rearing takes center stage this summer.

Building artificial nest boxes for wood ducks has become a favorite activity for conservation groups. Wood frame boxes will do, and so will old Freon canisters cut in such a way as to use the bottom of one and top of another, all riveted together and mounted on an old metal pipe pole over or near water.

Researchers have determined that the use of nest boxes by wood ducks can approach the 50 percent level in northern states of the Atlantic Flyway. However, in the Mississippi Flyway, box use is closer to 20 percent. Still, it is fun and worthwhile to place nest boxes in or near suitable habitats. At southern habitats of the United States, box use can be as high as 75 to 100 percent. High nest box use may indicate a lack of natural tree cavities. So in that case, wood duck boxes are filling a gap that the adaptable wood duck can use.

Wood duck boxes should have been inspected during January or February to help maximize their potential. Old nest material should be cleaned out. New wood shavings of three to four inches deep will serve as the basis for any new nests.

Wood ducks cannot bring nest materials into a man-made structure. That is why new wood shavings are needed. Inside a hollow tree cavity, a wood duck hen can work loose old tree pulp as a natural source.

Predator guards to help eliminate raccoon predation are important. A deep box places the hen too far below the reach of a raccoon’s arm. A metal wood duck box on a metal pole will suffice to prevent a raccoon from climbing it.

Predators in hollow trees may have an easier time if nest raiding is going to happen. Re-nesting will take place by woodies if a batch of eggs is lost. Given all the factors that lead to wood duck duckling survival into adulthood, researchers using radio transmitter devices have found survival rates can be as low as 20 percent. If, however, the habitat allows the hen to move hatchlings over long distances and into densely vegetated shrub growths, survival could increase to 60 percent.

Wood duck young escape their egg shell by using a small projection on their top bill to peck a hole into the shell, then gradually enlarging it. While still inside, the young have listened to the calls and voice of the hen, an imprinting process. Then after hatching, sight becomes another imprinting tool for the young to recognize their mother and siblings.

The hen will at the appropriate time stand on the ground below the nest and call to her young. They will one at a time climb the inside nest box or tree cavity to the exit hole, then jump down to bounce upon the ground and take cover under the hen. Once all young are out, the hen leads them to safe cover and food sources.

Researchers have also used hidden cameras to watch egg hatching. One thing that was documented was the hen assisting in taking egg shell fragments off the egg, then standing on the empty egg shell to crush it and eating the shell fragments. In some way, she was reincorporating that calcium back into her system. Another fact found by hidden cameras was that of the 33 eggs in one nest, perhaps from more than one hen, 31 hatched successfully. After they jumped to the ground, they trailed their mother to a nearby wetland.

————

What causes birds to migrate north in the springtime and south as fall and winter approach? The simple answer is photoperiod. Photoperiod is a lengthening of daylight each spring, and obviously a shortening of day length each fall for our northern hemisphere.

Migration is “hard-wired” in waterfowl and other birds. Day length affects hormone responses and starts the clock ticking. Feeding heavily to accumulate fat reserves prior to migration is one thing that happens, and molted feathers to have a set of viable flight feathers when needed is another. Come fall season, birds sense the decreasing day lengths, and their bodies adjust for the long journey south.

In the prairie pothole country of Canada and northern states like Montana, North Dakota and Minnesota, the season of fall will quickly transform toward more hostile conditions. Food sources change quickly and become hard to find.

By mid-November in places like Saskatoon, Saskatchewan, the average high temperature is below freezing. In North Dakota by January, the average low is below zero. Ducks will be long gone before that to locations of warmer temperatures, open water and food to sustain them.

Here is another fact worth noting: general patterns of temperature and precipitation in North America have remained largely unchanged for millennia. Snow accumulations in Bismarck, N.D. that began in November will finish melting in April, and that water from melting snow helps create optimal breeding habitat for returning waterfowl.

At sites like St. Joseph, Mo., precipitation declines during May, and thus germination of seed-producing plants in drying wetland basins is setting the stage for food for waterfowl when the fall migration of birds needs it. Much further south in Louisiana, peak rainfall usually begins in September which recharges coastal wetlands, especially for early migrators like the blue-winged teal.

There will always be variations of day-to-day weather. Remember that weather is short term. Climate is the very long term averages of inputs over thousands to tens of thousands of years of time. All along migratory corridors from the high north of Canada to the Gulf coast of the USA, weather variations are within normal ranges. Waterfowl take it all in stride and adapt to changes in food availability.

The total North American breeding population of wood ducks is estimated at about 3.5 million birds. Wood ducks comprise about 10 percent of the annual fall duck hunting harvest. Leg band returns indicate that about 1.5 million are taken by hunters annually. The breeding population is able, year after year, to easily replace itself.

Look for wood duck adults and later this spring, young wood ducks on the oxbow ponds at places like Arney Bend Wildlife Area, Grammer Grove or Timmons Grove. Make your late spring and summer hikes into these public wildlife habitats your observation time to see wood ducks go about their living.

————

A prairie burn, the managed type that is, may or may not happen during this coming week at the Grimes Farm. The exact date will not be known until all weather conditions line up in good order. Controlled prairie grass fire management is a tool in the conservationist’s tool box.

Fire invigorates tallgrass prairie grasses by getting rid of the overgrowth of cover from previous years. Fire takes away the dry material above the surface of the soil. Growth points of grasses below the soil surface are hardly phases at all.

The Marshall County Conservation Board can be called at 641-752-5490 to ask if a prairie burn is likely to happen. Also stay tuned to KFJB or KDAO radio for announcements concerning the possibility of a prairie grass managed burn.

——

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.

Contact him at:

P.O. Box 96

Albion, IA 50005

Newsletter

Today's breaking news and more in your inbox

I'm interested in (please check all that apply)
Are you a paying subscriber to the newspaper? *
   

Starting at $4.38/week.

Subscribe Today