UPDATE – 1 Non-Migratory Whooping Crane Flock in Florida

Monday, April 05, 2010
Marty Folk, Avian Research, Florida Fish and Wildlife Conservation Commission reports that, “We continue to study the non-migratory flock of whooping cranes in Florida. This is the first report I’m sending out for our 2010 Breeding Season. Please share this within your respective organizations and with other professional associates that might be interested.”

Marty explains, “We entered the 2010 breeding season with 26 birds (10M:16F), 10 pairs. Marsh water levels are the best we’ve seen since 2006. To enhance our knowledge of reproductive biology we have been collecting, since last fall, behavioral observations on frequency of copulations. Also, this spring, in addition to continuing our video surveillance of nests to document incubation behavior, we are conducting a “pilot” study of measuring the temperature within crane nests via artificial data-logging eggs. Partners for this study include Billy Brooks of the USFWS (provided data loggers), Donna Bear-Hull of the Jacksonville Zoo (her team constructed the eggs), and Marilyn Spalding of the University of Florida (necropsy and tissue salvage from collected eggs). My agency (FWC) provided transmitters to go inside the artificial eggs to allow tracking of any “wayward” eggs that might disappear from nests. I don’t have room here to go into detail regarding the egg construction and deployment protocols, but let me summarize it to say that single egg clutches are simply supplemented with an artificial data-logging egg. For 2 egg clutches we remove a natural egg and leave the data-logging one. Natural eggs collected from the wild are humanely killed and if fertile, tissues used for IBD research. We are collecting concurrent data on behavior (gathered via video surveillance) and nest microclimate (from the data-loggers) from nests of whooping and Florida sandhill cranes. Results from this work may allow us to:

1) compare, contrast, and describe basic behavioral biology of nesting whooping and sandhill cranes
2) determine if there are behavioral reasons why some whooping cranes are unsuccessful at hatching eggs in Florida
3) make recommendations to captive facilities on how to adjust incubators to improve hatching success
4) provide baseline data for successful incubation behavior that can be used for comparisons with other reintroduced flocks of cranes.”

Several groups have done some work with data-logging eggs with nesting captive cranes (George Gee et al., Calgary Zoo), but to my knowledge no-one has done this with wild crane nests. The Florida flock of whooping cranes presents a unique research opportunity. The chances of this flock becoming self-sustaining are low, and there are no plans for further releases. However, the flock is available for study and experimental manipulation at a level that has not yet been conducted with other crane flocks.

Marty continues, “It has been an interesting breeding season. Thus far 6 whooper nests have been initiated. The first nest (Lake County) failed when the pair abandoned their nest for unknown reasons. We do not suspect it was in response to the deployment of the data-logging egg because they didn’t abandon their nest until several days after deployment of the egg. This pair re-nested and currently are actively tending their nest.

Another nest was initiated in Osceola County. This nest failed within the range of dates for “expected hatching”. Early in incubation we had deployed an artificial egg into the nest. Upon visiting the failed nest, the artificial egg was found in several pieces and there were teeth marks in the pieces. The teeth marks were similar in appearance to those seen when alligators have chewed on transmitters. Despite this, the egg transmitter and datalogger were successfully recovered from the floor of the marsh. The natural egg was missing. The nesting pair was not tending the nest and the female was found to be missing an entire leg (there were no blood stains on the bird, simply no leg visible below the feathers. Fortunately it was not the transmittered leg that was missing). The bird was flight capable and wary. The quality of the surveillance video for this nest was very marginal due to the distance between the camera and nest, however, it did show that the evening (several hours before sunset) prior to the discovery of the failed nest, one bird struggled near the nest while the other stood on the nest with outspread wings. Apparently an alligator caught the bird in “broad daylight”. The night after this discovery (the female’s 2nd night as a one-legged crane), she was taken by a bobcat. This was a 10 year-old female.

Another nest in a vast marshy area of Lake Okeechobee came as quite a surprise because the “pair” consisted of 2 females. The older bird had nested previously with a male, but now she was with a wild-hatched bird that had been identified via blood sample as a female. Of course there can be “errors” in the identification of gender. When this pair moves to an accessible/assessable location we will observe them for behavioral clues as to gender. They currently are in a remote area 5 miles from the nearest uplands. (Monitoring has been from the air).

The next nest was initiated in Lake County. The male of this pair last nested in 2006 with a different female in the same marsh. 2006 was the last time, until now, that the marsh had water. This spring’s nest, 4 years later, is within 80 m of where the 2006 nest was. We are collecting behavioral and temperature data from this nest.

A new nest was discovered just now in Lake County. Two other whooper pairs have been observed doing some nest-building so we may have more whooper nests to study in the near future.

In addition to the whooper nests above, we have collected behavioral data at one Florida sandhill crane nest. We plan to collect behavioral and temperature data at one or more additional sandhill crane nests yet this season.