Back in March the Whooping Crane Recovery Team met at a crane conference in Nebraska to discuss all things whooping crane including making decisions on how many eggs/chicks to allocate to each of the various reintroduction projects in 2011. Requests on how many chicks were desired had been submitted to the recovery team prior to this meeting. The team recommended trying to meet the requests of all of the projects but also set acceptable minimums in case the captive production wasn’t able to meet all of the full requests. Our request was for up to 20 birds and the recovery team set our acceptable minimum at 16. Of course these are only numbers that will hopefully be achieved and unfortunately the production at the captive facilities got off to a rough and slow start this year.
There are years where one facility has a bad year but usually the others do well enough to make up for the loss. Unfortunately early on this year not just one but, several of the captive breeding facilities were having difficulties. Birds weren’t laying eggs, eggs that were laid were turning out infertile or were being broken before they could be collected from the cranes. Some birds shut down and molted early, a sign that breeding season is over, and some females were very late in starting to lay eggs, shortening the length of their egg production season and ultimately the number of eggs they would produce. Captive production was looking grim. It’s all a bit of a guessing game or a crystal ball prediction as Tom Stehn, leader of the recovery team likes to say and unfortunately the crystal ball predictions were coming up short, way short, of the number of chicks that were desired. So the recovery team convened again on the phone and through email to make a revised allocation strategy given the low production.
Based on years of captive breeding records we calculate that 25% of the hatched chicks won’t make it to fledging or release. As I said before, being a whooping crane chick is difficult. Of course there are some years where survival is much better than 75% and other years where it’s worse. The recovery team wanted us to end up with at least 12 chicks so they allocated 16 hatched chicks to start out. Of course this number was lower than what we hoped for but that’s just the way it was.
Luckily as time went on there was a bit of a late season rally. More fertile eggs were available than initially thought and with extremely high hatchability at Patuxent this year there are currently 18 hatched chicks being raised for the Louisiana reintroduction project. Additionally there are 2 final eggs that will hatch this week. Of those 20 chicks 2 will likely be held back in captivity due to their high genetic value leaving us with 18 hatched chicks and so far they’re apparently healthy and doing well. We still can’t count our chicks before they fledge but things are definitely looking better than we predicted earlier. If all goes well we hope to welcome as many of those 18 chicks as possible into the 2011 cohort that will be shipped to Louisiana later this fall. Stay tuned for additional updates.
Update written by Sara Zimorski