Adaptability of Bewick Wrens to Nest Molestation
Adaptability of Bewick Wrens to Nest Molestation.-By March 18, 1947, a Bewick Wren (Thryommm bewickii) had succeeded in completing a clutch of five eggs in her nest constructed in the glove compartment of a truck at our ranch in northern San Diego County, California, although the truck was gone most of the day from its place part way into an open double garage. At 6: 15 a.m. of March 18, I frightened the bird from the nest and transferred the nest into a large oatmeal .cartOn. This I placed on a keg. Over all I draped an old carpet, letting its edge extend over the box opening, trying to effect a cave situation which might be acceptable to the wrens. The keg I placed on the garage floor in the same relative position as the nest had been when in the truck, but some four feet lower.
At 9:40 p.m. the day of the transfer the bird was on the nest in the new situation. After submitting to much close observation and much coming and going of cars and people, the wrens successfully brought off the nestlings at IO:@3 a.m. on April 18. I believe all tive were raised as I found no eggs left in the nest, although I did not get a count of the nestlings.
Two earlier attempts to move nests of this species were not successful. The first, in April, 1945, involved a nest built in a rubber boot reclining in an orange pi&ii box. The nest had to be lifted out when the boot was needed and put in the dark comer of the same box. This nest was completed and two eggs added before the birds abandoned it.
In 1946 a nest was built in an empty carton, the sixth and top of a stack of empty cartons containing lengths of garden hose. When the hoses were needed. empty cartons were substituted for the ones removed, so the nest carton kept its same relative position and the nest was untouched. Three birds, hatched from the clutch of four eggs, were being fed regularly when, during one change of cartons in the stack, the lid of the nest carton was jarred too nearly closed to permit the adults to enter. Their commotion attracted attention, the lid was adjusted, and they were seen to continue feeding and sanitary work. The length of time the birds could not enter was not known but was of short, day-time duration. The following day the birds were not seen at the nest and the unfeathered nestlings died. Human molestation was least in this instance and may not have been the factor which caused abandonment of nest and young.-ELEANOR GUYER BEEMER, Pala California, April 22,1947.