In the locality of my study racers spend approximately half the year in winter dormancy. Earliest spring records and latest fall records for 13 years are shown in Table 4. The spring records in nearly all instances pertain to snakes found in the open or beneath flat rocks warmed by sunshine, usually at or near the rock ledges where hibernation occurs. Juveniles are especially well represented in these earliest spring records, and it seems that they tend to emerge a little earlier, on the average, than the adults, either because they have hibernated in more superficial and less well insulated situations or because their lesser body mass permits more rapid warming to activity than can occur in the adults. The latest fall records all pertain to racers trapped along the rock outcrops, and none was a young of the year. Table 4. Earliest and Latest Recorded Annual Dates When Blue Racers Were Active on the Reservation or Rockefeller Tract ==========+==========+=============++==========+==========+============ | Earliest | Latest || | Earliest | Latest Year | spring | fall || Year | spring | fall | record | record || | record | record ----------+----------+-------------++----------+----------+------------ 1950 | April 16 | November 4 || 1957 | April 30 | November 2 1951 | April 19 | November 13 || 1958 | April 25 | November 20 1952 | April 23 | November 12 || 1959 | April 6 | November 10 1953 | April 8 | November 12 || 1960 | April 22 | November 6 1954 | April 20 | November 12 || 1961 | April 19 | November 1 1955 | April 15 | November 2 || 1962 | April 23 | October 27 1956 | May 11 | November 14 || | | ----------+----------+-------------++----------+----------+------------ Most of the population undoubtedly emerged somewhat later than the average date of April 16 indicated by the records in Table 4, and retired somewhat earlier than the average date of November 8. However, a small percentage of the population probably emerged even earlier each year than my records indicate, and retired into hibernation later than my records indicate. In a typical year, temperatures in April and early May are only occasionally above the level at which racers are able to become active, but are below this threshold most of the time. The same statement applies to an autumn period of late October and November. Most racers are dormant in their hibernacula during these transitional periods of spring and autumn, but some--those that have emerged early in spring, or those that have not yet retired (in fall)--retreat to temporary shelters and revert to a semi-torpid state when temperatures fall below the critical level.