Calving Rates and Intervals of East Australian Female Humpback Whales

Project Name:  

Calving Rates and Intervals of East Australian Female Humpback Whales

Study System:

East Australian humpback whales (Megaptera novaeangliae

Motivation and Goals:  

Knowing the percentage of females that give birth each year as well as knowing the interval between births will greatly aid in managing this population of humpback whales. Calving intervals and reproductive rates are an important vital metric for determining population trends and predicting how population abundance may be affected by continuing human impacts.


For this long-term research project, we have been documenting East Australian humpbacks since 1984 using the Southern Hemisphere Humpback Whale Catalog.  A humpback whale is known to be a female if it is seen with a calf.  When possible, we can also use photographs of the genital region to determine sex. These observations have been collated into reproductive histories for over 1000 females in East Australian study areas. 

Results to Date:

Our estimates of calving interval are generally consistent with those found for other populations of humpback whales, and our models suggest that females with calves are more easily sighted than other demographic groups.  Females may adjust aspects of their reproductive behavior based on population growth rate, but further research is needed to analyze such relationships.

Next Steps:

To gain a more complete picture of the life history of East Australian humpback whales, future models of calving interval should also incorporate other life history parameters such as survival of calves, juveniles, and adults. 

Most Recent Publication:  

(In press):  Rankin, R.W., Maldini, D. and Kaufman, G. Bayesian estimate of Australian humpback calving interval under sparse resighting rates: 1987 - 2009. Journal of Cetacean Research Management.