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International Crane Foundation

 

What can Sandhill Crane nesting teach us about Whooping Cranes at Horicon Marsh?

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A Sandhill Crane nest spotted during this spring’s aerial survey over Horicon Marsh.

It was my first time in a helicopter, and the experience of flying low over the snow-covered landscape of eastern Wisconsin was truly special. From the air, we saw a multitude of geese, ducks, deer and many other animals – and, of course, cranes, including one Whooping Crane!  Overall, we located 31 active Sandhill Crane nests, four potentially inactive or predated nests, and five additional pairs that did not have a nest yet, but may have been on their nesting territory.

Due to the weather – we completed our survey after a record-breaking spring snow storm – we were unable to survey the entire wetland basin, but we were able to get enough information to estimate the number of nests in the area. The next big step was to set up remote trail cameras on a subset of the nests that we found. From those images, we will be able to observe nest outcomes, determine when chicks hatch, and relate nest success to habitat characteristics.

A Sandhill Crane nest with two eggs at Horicon Marsh.

I am studying Sandhill Crane nesting in the Horicon basin to help us better understand the potential for Whooping Crane nesting in this area. In 2011 the Whooping Crane Eastern Partnership, of which the International Crane Foundation is a founding member, began releasing captive-reared Whooping Crane chicks in eastern Wisconsin at Horicon National Wildlife Refuge.

This release area was chosen based on low populations of crane-feeding black flies, which have caused Whooping Cranes to abandon their nests at the original release site in central Wisconsin, Necedah National Wildlife Refuge. Studies at Necedah show that there are higher hatching rates in years either with lower black fly populations or from nests initiated after black fly emergence. However, even with higher numbers of chicks hatching at Necedah, chick survival rates and eventual recruitment are still too low for the population’s self-sustainability.

Sandhill Crane Project Manager Andy Gossens sets up a nest camera at Horicon Marsh.

This led us to ask whether there are other factors that could be influencing chick survival even without the presence of black flies. Current research being conducted at Necedah is exploring causes of mortality and the influence of habitat management on chick survival and is comparing survival rates between Sandhill and Whooping Crane chicks. Preliminary results indicate similar chick survival rates and recruitment for both Sandhill and Whooping Cranes within the refuge.

We are developing a study paralleling the research at Necedah to evaluate crane nest success and recruitment by addressing three general objectives: (1) estimate general breeding density for Sandhill Cranes in the Horicon Basin (on both state and federal properties), (2) measure nest success and determine if it is influenced by water levels or management of cattail densities, and (3) monitor chick survival rates to fledging (when they begin to fly).

We are using helicopter surveys, nest cameras, and information collected on the ground at the nest, such as vegetative structure and water depth around the nest. Once chicks have hatched, we will be conducting ground surveys to monitor their survival. Members of the public who see family groups will be able to report their sighting data back to the Crane Foundation using a mobile phone app — a great opportunity for citizen scientists to get involved with crane research.

By conducting our study with the same questions and methods as the research at Necedah, we will be able to compare results and determine if there are differences in recruitment for Sandhill Cranes nesting in the two regions, and make a prediction for future nesting attempts by Whooping Cranes at Horicon Marsh based on the comparison of the species.

This helicopter survey would not have been possible without the generosity of David Moore – thank you!

If you would like to sponsor an up and coming conservation leader like Sabine please email Development Director Kari Stauffer.

Story submitted by Sabine Berzins, North America Program Intern. Click here to learn more about our work in North America.