Suckling behaviour in the brown long‐eared bat ( Plecotus auritus )

Thirty‐two adult female brown long‐eard bats were taken into captivity. Eight individuals gave birth to single young in captivity (known mother‐young pairs), 10 were lactating when captured (putative mother‐young pairs), and the remaining 14 bats were non‐reproductive. Bats were maintained in five groups consisting of females from sigle(n=3) or mixed (n=2) wild roosts. All bats were housed in outdoor, free‐flight enclosures and fed mainly on free‐flying noctuid moths. Bats were individually were determined daily (n=152) for a single gruup of bats containing four known mother‐young pairs and five non‐reproductive bats. The probability of a being attached to the nipple declined from 100% of records at 1‐5 days of age to 5% of records at 36‐40 days of age. Females were always found suckling their own young. Suckling associations were determined using infra‐red sensitive video‐recordings of bat behaviour within the roost box. For both known (n=8) and putative mother‐young pairs (n=10), there were no records of young attached to lactating females other than their own mothers (from the same or different wild roosts).