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Mark Berres on Sandhill Cranes and genetic bottlenecks – Audio

Mark Berres, Avian Biologist
Department of Animal Science
UW-Madison College of Agricultural and Life Sciences

3:40 – Total Time

0:17 – The homing tendencies of Sandhill Cranes
0:38 – Why breeding patterns are important
1:21 – What caused the decline in crane numbers
2:00 – The genetic difference between groups of cranes
2:45 – What’s ahead for Sandhill Cranes
3:30 – Lead out

[audio:|titles=Mark Berres on Sandhill Cranes]


The genetics of the Sandhill Crane. We’re visiting today with Mark Berres, Department of Animal Science, University of Wisconsin, in the College of Agricultural and Life Sciences, Madison, Wisconsin and I’m Sevie Kenyon.
Sevie Kenyon: Mark, welcome to our microphone. Mark, can you typify for us the genetics of the Sandhill Crane?

Mark Berres: Offspring of any breeding events of the cranes in these areas, they tend to return to their natal site of origin. And, technically it’s called philopatry and this is very common amongst the majority of species of birds.

Sevie Kenyon: And Mark, why is this important to us?

Mark Berres: What happened was the population size was reduced so much that the amount of genetic diversity was only a tiny fraction of what was there originally. So, even though cranes themselves did not go extinct, it’s that the breeding opportunities now were very, very limited. The offspring were likely interbreeding with their relatives….expressly, the definition of in-breeding in itself.

Sevie Kenyon: Mark, can you describe for us what caused the bottlenecks?

Mark Berres: One was just unregulated hunting. I mean, at the time there was no limits on what you could shoot. And much of this had to do for subsistence. Moreover, at the same time, much of the breeding habitat that these cranes used was actually swamp land, which was actually being drained, for reeds for the carpet industry. And so there was wholesale decline in the availability of suitable breeding sites.

Sevie Kenyon: Can you tell me the difference between one clan and the other, genetically?

Mark Berres: We have the technologies to track individual genes throughout populations. We can create very sophisticated pedigrees essentially as far as who is related to who. And so what we think is happening is that while there was likely more then 25 pairs that actually passed through that bottleneck. But. they were far enough separated so that if by chance, happenstance that they were able to cross… to essentially breed with each other, the cranes actually lucked out in terms of saving much of that genetic variation.

Sevie Kenyon: Mark, can you give us a sense for what’s ahead for these birds?

Mark Berres: What we really need to do right now is kind of look at the Sandhill Crane as somewhat of a success story. One of the reasons for this success is really people. People at the last minute, they really came together and they recognized that there’s a problem here, and I think we really need to look, historically, what has been done in the past to help guide us to the appropriate decisions that we really need to make not just for the continued benefit for the Sandhill Cranes, but really all species, including humans.

We’ve been visiting with Mark Berres, Department of Animal Science, University of Wisconsin, in the College of Agricultural and Life Sciences, Madison, Wisconsin and I’m Sevie Kenyon.