In the springs of 2000 through 2003, the Pennsylvania Game Commission collected reproductive data from 3,180 road-killed female deer from across the state. By measuring embryo size, noting the date of the doe's death, and knowing that Pennsylvania white-tails have a gestation period of about 200 days, conception and birth dates can be accurately estimated. From this data, PGC biologists determined:

For adult does more than one year old

• 90 percent give birth from May 12 to June 27 (peak date May 30).

• Among does 3 years and older, 22 percent carried single embryos, 73 percent carried twins, and 5 percent carried triplets.

For does less than one year old

• 90 percent breed between Nov. 5 and Jan. 16.

• 90 percent give birth from May 22 to August 4 (peak date: June 19).

Practical conclusions

• Spotted fawns seen in May and early June are almost always the offspring of mature does. Spotted fawns seen in late July or August are almost always the offspring of fawns from the previous year.

• Spotted fawns seen in late summer are less likely to survive the winter because they come from young females and won't have enough time to fatten up for the winter.

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