Leg problems and banding-associated leg injuries in a closely monitored population of North Island robin (Petroica longipes)

Abstract

Although plastic and metallic leg bands are widely used for identifying individual birds to assist population monitoring, the health risks associated with banding are quantified relatively rarely. We recorded the general occurrence of foot and leg injuries during a four-year study of the North Island robin (Petroica longipes) and assessed the probability of banding–injury relationships. While most leg problems were not obviously related to banding (transient lameness, congenital deformity, infection, fracture), on 10 occasions individuals experienced lameness or injury directly because of the presence of bands (~2.5% of individuals per year). In eight of these instances, individual robins caught their back toe (hallux) in between a band and their tarsus. This resulted in an inability to place the affected foot on the ground, and in some cases a pedal injury. We believe that this previously undescribed toe entrapment is made possible because of the robin’s sideways perching behaviour on upright vegetation. This highlights that relationships between leg banding and injury may be species-specific and that the impacts of banding should be identified and quantified in all species in which it is used. This will allow more accurate assessments of the risks and benefits associated with this common marking technique.