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J.C. Borneman

Publications and source records attributed to J.C. Borneman.

9 recordsLinked to original sources
USGS1974

Supplemental feeding program for California condors

A 2-year supplemental feeding program for the endangered California condor ( Gymnogyps californianus ) was of insufficient length to definitely show that a dependable food supply will stimulate additional breeding; however, production did increase during the study, and food supply appears a likely cause. Because no undesirable effects of feeding were noted, and because condor production is now critically low, an expanded supplemental feeding program is recommended.

California↗
USGS1972

Copulation by California condors

Koford (Res. Rept. No. 3, Natl. Audubon Soc., 1953) observed sexual display among California Condors ( Gymnogyps californianus ) on more than 30 occasions, yet only once did he see what he thought was copulation. Some of the displays he watched were quite intricate, with considerable posturing and "male" aggression, but no such activity preceded this copulation. The birds sat several feet apart for over 1 hour, then one climbed onto the other's back, staying there 1/2 minute and flapping gently at the apparent moment of coition. Afterward they sat quietly 1/2 hour before flying away. This led Koford to state (p. 79) that "possibly in Gymnogyps copulation is not immediately preceded by display." We have records of 8 California Condor copulations, 5 of which are similar to that described above. The three other occasions began similarly, with the birds sitting quietly, but then the "male" displayed briefly before the "female" with wings half spread and head drooping forward. This elicited no apparent response, but the male immediately walked behind and mounted the female. The apparent moment of coition was accompanied by gentle wing flapping in all instances.

The Auk↗