ZIBBLE, D.O. 1986 Peromyscus boylii (L04 -7) Hastings Reservation, Monterey Co., CA July 3 (cont) 0100 ♂, mature, nonbreeding. Toe-clipped; released. Trapline XIII, West Ravine (TC's R) 0110 ♂, immature, nonbreeding. TC & R. 0120 ♂, immature, nonbreeding TC & R 0130 ♀, mature, vulva scabby, paras. TC & R 0140 ♀, immature, nonbreeding. TC & R. 0200 ♀, mature, nonbreeding, early pregnancy TC & R July 4 0200 ♀, mature, vulva closed, paras. TC & R. Trapline X, Robertson Creek Canyon. 0230 ♀, mature, vulva crusty, paras TC & R 0240 ♂, immature, nonbreeding. TC & R 0300 ♂, mature, nonbreeding. TC & R Nelson P. boylii: Of all the Peromyscus, boylii is by far the most nervous & aggressive. It is the hardest to handle & tries to bite any chance it gets. It always hops & escapes off swiftly when released. Morphotology Given the number of captures & lack of long term recaptures, they seem to be very transient. Morphologically, boylii can be distinguished by its shorter ears, and the skin of the penis is thicker & smooth. True's ears are generally wrinkled. Finally, the tail of boylii is unique - it's the longest of the Peromyscus, and is very easily lost or shortened by handling & the number of individuals caught with shortened tails. July 25 0110 ♀, immature, nulliparous. 12g. Toe-clipped; released. Grid WL-1 (meadow Canyon) St. 5,5 0120 ♂, early mature, nonbreeding. 19g. 0210 ♀, mature, nonbreeding. 22g Previously tagged, but lost it. 0220 ♂, early mature, non breeding July 26 0340 ♀, mature, nonbreeding, paras, 24g 0230 ♂, mature, nonbreeding, 21g Previously ear tagged but lost it 0230 ♀, mature, nonbreeding, appears paras Previously ear tagged but lost it