TO: Aransas NWR staff

FROM : Tom Stehn 8-25-98

SUBJECT: Whooping crane chick numbers
 

Whooping crane coordinator Brian Johns of the Canadian Wildlife Service CWS on August 18-21 located 24 juveniles in Wood Buffalo National Park. He believes he found all the pairs that had chicks in June so he does not think there are more than the 24 chicks surviving. All are single chick families.

Last August, 30 chicks had been sighted on August surveys, with between 32 and 36 chicks estimated present. So production is down this summer compared to the record of last summer.

I anticipate about 20 chicks will arrive at Aransas this fall. With the average loss of about 8 adults between spring and fall, I expect the population to increase by 10 to 12 birds this winter. This should put the flock slightly above 190, a definite increase from the 181 present last spring and the 182 record peak population last winter. Since mortality can always be higher than expected, 190 whooping cranes is my hoped for target this winter. This would be a 4 % increase from last winter, which is the average annual growth rate of the Aransas/Wood Buffalo whooping crane population.