Behaviour of hand‐reared orphaned long‐eared owls and tawny owls after release in the wild

Abstract

Two groups of eight long-eared owls, Asio otus, and eight tawny owls, Strix aluco, which entered a Rehabilitation Centre as nestlings, were studied. When more than 60 days old they were released to the wild. The aim of this study concerns the analysis of their behaviour immediately after release and their adaptation to natural life. The owls were radio-tagged and followed continuously, also with direct observation, until they disappeared from the area or died. The long-eared owls, released in an agricultural area with scattered woods, were reluctant to fly frequently and remained mostly in thick vegetation along stream banks or very close to the release pen itself. Nevertheless, they progressively enlarged their home range in a matter of days. Half of them disappeared from the study area within 11 days; three others died in a few days, apparently from starvation, while the last owl was rescued because it fell into a stream. In contrast, the tawny owls had a much better survival rate, as only one out of the eight died because it was preyed on in the early days. The birds remained in the area for a longer time, constantly within the woods, and flew more often. They, too, enlarged their home range but only until day 10, when there was a contraction in size. Thus, inexperienced hand-reared owlets are able to survive in the wild, but the possibility to cope with the new environment varies greatly between species, possibly due to environmental characteristics.

Survivorship of Rehabilitated Juvenile Tawny Owls (Strix Aluco) released without Support Food, A Radio Tracking Study

“…Their conclusion was that short-term survival (75%) was sufficient to justify the rehabilitation process. Csermely (2000a) tracked eight juvenile Tawny Owls for 7 -79 days, recorded only one death by predation and drew a similar conclusion to Bennett and Routh (2000). More recently, in a larger group of 16 juvenile Tawny Owls, Leighton et al (2008) reported a survival rate of at least 37% six weeks after release.…”

Porcupettes Management at Wildlife Rescue Centers and Liberation into the Wild: Implications for Post-Liberation Success

“…The debilitation state in which M1 was recovered allows for us to hypothesize that an inability to search for food after liberation is a possible cause. This could suggest that long detention periods can lead porcupines to develop addiction towards human-supplied feed, as also observed in wolves and birds [22][23][24][25][26][27][28]. Therefore, M1-post-liberation behavior could lead to other attributes as the causes of unsuccessful liberation.…”

High-Tech Training for Birds of Prey

“…Therefore, physical strength recovery (not only general weight regaining) is an actual fitness prerequisite that will determine the raptor’s fate in the wild, mainly in the first few days. Csermely [ 10 ], in fact, stresses that half of the released birds of prey die from starvation within one week of release.…”

“…Rehabilitation standards and pre-release screening can be different from one rehabilitation center to another but usually, a rescued raptor is considered recovered after having regained weight, being able to fly, and completed a molt [ 8 , 10 , 11 ]. Although a short recovery period and quick release are always desirable, in case of prolonged hospitalization it could be useful to wait for a molt.…”