International Crane Foundation

 
long_term_research_tom_lynn

Long-term Research

long_term_research_tom_lynn← Sandhill Crane Conservation

ICF started banding Greater Sandhill Cranes in our study area near Briggsville, Wisconsin (near the intersection of Columbia, Adams and Marquette counties in south central Wisconsin), in 1990 (right, ICF staff band a Sandhill Crane chick, photo by Tom Lynn). Cranes are long-lived and have a complicated social structure; by banding mated breeding pairs and their chicks, we are able to learn more about the behavior and ecology of these birds. In the past, topics of research within this study area included habitat selection at multiple scales (spatial and temporal), habitat selection of breeding cranes, and divorce and extra-pair paternity. Our current work includes examining  how long pairs stay together and their yearly success at raising chicks, how far young birds disperse from the marshes where they hatched, and how to reduce and prevent crop damage by cranes. Frequently monitoring an identifiable population of cranes makes it possible to answer these far-reaching questions.

In order for us to monitor these cranes, captured individuals are marked in several ways (see examples here). Each crane is outfitted with colored leg bands and an aluminum band from the United States Fish and Wildlife Service (USFWS). Some cranes, in addition to the color and aluminum bands, have a radio transmitter glued to their leg bands or worn like a backpack with a harness made of Teflon ribbon. Specific color combinations, numbers, and transmitters (with their own unique frequencies) serve to identify each crane. In this way, the movements of each bird can be tracked for a variety of purposes.

To date, ICF ecologists have banded 369 Sandhill Cranes near Briggsville, WI, and an additional 53 in northern Wisconsin, Minnesota, Michigan, and southern Ontario. With the help of the banding program, over 60 territories within the 30 square mile study area have been identified.  We have recorded some cranes using the same territories since color-banding began in the early 1990s, while others have occupied multiple territories through the years. For instance, one banded pair of cranes has defended the same breeding territory since being banded there in 1993. We have been able to follow their productivity over the years and are currently tracking (with backpack transmitters) the movements of two chicks that they successfully raised in 2007. Alternatively, a breeding female banded on one territory in 2006 (fledging one chick) has since occupied two separate territories with different mates in 2007 and 2008. Collecting information on these banded cranes through multiple breeding seasons allows us to better understand their social structure, productivity, and how outside factors influence crane populations in general.

The Greater Sandhill Crane population, in Wisconsin and elsewhere in its range, has been steadily increasing over the past several decades. In the 1930s there were only an estimated 25 pairs in all of Wisconsin; currently the state population stands at approximately 15,000 individuals. As a result of this population increase, many biologists and enthusiastic birders have been observing Sandhills in places where they have not usually, or in some cases only recently, been sighted. In the past five years, Sandhill Cranes have been expanding their breeding areas in Quebec, Canada, and they are being observed during the summer in the northeast United States for the first time in a century.

Likewise, similar trends are being observed on wintering grounds. Sandhill Cranes in the eastern portion of the United States (i.e., east of the Mississippi River) typically winter in southern Georgia and Florida. With the population increasing, however, many birds are starting to find new areas to winter. In 2000, a birder in Mississippi observed one of our birds in a flock of about 100 Sandhill Cranes in the northwestern part of that state. In 2002 and again in 2003, a graduate student studying Sandhills in Louisiana observed cranes with our bands during the winter. It may be that Wisconsin Sandhill Cranes are starting to branch out and find new wintering areas and develop new migration routes. The population has increased so steadily that perhaps Sandhills are beginning to utilize areas that they haven’t used for many decades. Since we do not follow the individuals we have banded to their wintering grounds the only data we collect comes from outside observers who report sightings of banded cranes during migration. For this reason, we encourage anyone who has seen cranes with leg bands outside of Wisconsin to contact us.

In Wisconsin during the breeding season, we are always searching for banded cranes, but there are still individuals we have not seen for years and a wealth of information we have yet to learn. While it is true that you are more likely to see a banded bird if you are close to our study area, birds banded by ICF have been observed in fifteen counties throughout Wisconsin. Cranes banded by ICF have been reported as far as Lincoln, Manitowoc and Portage Counties. We always look forward to reports of banded cranes being seen outside of our study area during the breeding season.

So, if you are bird-watching at any time of the year, look for color bands on the crane legs you see. You may be surprised at what you find. Oh, and don’t forget to look at the color of the body as well. It may just be a Whooping Crane!

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If you are interested in learning more about Sandhill Cranes, participating in the Annual Midwest Crane Count, sponsored by ICF, is a great opportunity to observe these birds in the wild. Through the Crane Count, over 3,000 observers in the Upper Midwest (Wisconsin, Illinois, Iowa, Indiana, Michigan and Minnesota) count cranes one morning in April each year.

Receiving observations of banded birds during this time can help us a great deal. Of course, any time that you see a banded bird is important, and we hope that you will report it to us at ICF. You can report bands from any location at any time, and we’ll provide a biography of the bird once we are able to determine the identity of the individual.