Will the Whooping Crane Partners Opt for Black Fly Suppression?

By 2005, four individual birds in Wisconsin’s growing flock of whooping cranes had formed pairs and made a first attempt at nesting. No one was surprised when the two nests that resulted were unsuccessful – these were still young and inexperienced birds. When one of the pairs succeeded in 2006 in welcoming the first wild whooping crane hatched in Wisconsin in more than a century, the wildlife community was jubilant. And optimistic that more such successes would naturally be following in succeeding years.

Parent and chick: Wisconsin is yearning for more of these – in the wild. (Photo courtesy of ICF)

But three very long years would pass before even a single wild chick would once again hatch in Wisconsin, and four years before another one hatched and survived. Instead of chicks hatching, what was happening during this time were mounting numbers of “nest abandonment.” Over time it was observed that many pairs, after forming and building a nest together, were suddenly leaving that nest and not returning.

WCEP Studies Nest Abandonments

By 2009 this problem was being actively studied and various hypotheses were put forward by officials of the Whooping Crane Eastern Partnership – the actual folks responsible for bringing the whooping crane back to eastern North America, and Wisconsin, in particular. These included theories that maybe the cranes were too inexperienced in the wild, or were undernourished, or too stressed by predators, or harassed by biting black flies, or something else.

I don’t think it took long for the biologists involved in closely monitoring the nesting whooping cranes to notice large numbers of black flies on some of the incubating cranes. But it has taken a while for this, and the various other hypotheses to be tested – science, after all, takes its time, and the scientists, understandably, want to get it right.

Are More Bti Treatments the Answer?

However, the citizen scientists and fans of progress for the whooping cranes in Wisconsin – myself among them – who were tuned into the Wisconsin DNR’s Ask The Experts online chat last week, seemed to be expressing a lot of eagerness for a continuation of Bti treatments to reduce the Black fly population. Bti is Bacillus thuringiensis israelensis, a naturally occurring soil bacterium – considered a good alternative to chemicals used to suppress insects. It was applied in certain areas of Necedah National Wildlife Refuge in 2011 and 2012, to see if fewer black flies would result in fewer nest abandonments by whooping cranes.

It seems like it did, in fact, help. Here is a page all about it at the WCEP website. I once saw a picture of a nesting whooping crane covered with nasty looking black flies, and hoped to find and link to it for this post; while my quest for it was unsuccessful, I urge you to look closely at the eggs in the photo on the WCEP page – they are covered with the flies, and seem to tell the story!

At the Ask the Experts event, Davin Lopez, the DNR whooping crane coordinator could only say that the matter is still being studied. But he seemed to promise that a decision will be forthcoming in winter, 2014. The decision will be made by the WCEP partners, but for now Davin offered the opportunity to contact him directly, Davin.Lopez@wisconsin.gov , for those with more question or comments.