A REVIEW OF EXPERIMENTS IN BIOLOGICAL CONTROL OF RABBITS IN AUSTRALIA

time each year, probably five or six weeks prior to the resurge in hatching, since it takes at least 35 days for a clutch to be laid and incubated. This would place it in the middle third of May and would throw strong suspicion on some farming practice, probably plowing, as being the responsible agency. The hatching distributions presented here illustrate the degree of refinement that can be obtained from a state-wide, envelope system of collecting specimens from hunters for age determination. Further refinement probably is not possible, inasmuch as information furnished by hunters on location of kill may not be reliable below a county level. The county groupings, however, have proved sufficient to distinguish some major population differences, and the system will be continued in order that any future population fluctuations can be fully covered. Accepted for publication January 19, 1953.