Table 1.
Overview of species (listed by increasing body weight) reported to have problems caused by plastic or metal rings.
Figure 1.
Brown Thornbill where the leg on the right of the picture is ringed with a metal-on-plastic ring, with the metal protruding so the plastic does not make contact with the foot.
Thornbills are known to react negatively to plastic colour rings that touch the feet. While the metal-on-plastic ring method solved this problem, Brown Thornbills on Tasmania reacted to plastic colour rings in upper position (see Fig. 4).
Table 2.
Body measures and ring measures of the study species.
Figure 2.
Siberian jay with partly unwrapped wrap-around colour ring stuck over the foot.
The yellow plastic ring was mounted on top of the metal ring but slipped over the metal ring when the bird tried to remove the plastic ring. This individual was colour ringed as a juvenile in autumn 2002, and recaptured in October 2003 with the colour ring partly stuck over the foot. It subsequently dispersed in spring 2004 to the neighbouring group where it became a breeder.
Figure 3.
Likely sequence leading to leg injuries in Purple-crowned Fairy-wrens.
A fine bracelet of spider web caught on leg (a) attracted other material to form a constricting ring around the leg (b) which gradually cut into the leg causing swelling (c). Injuries usually healed rapidly if rings and constricting material were removed early enough (d). The constriction could form above, below, or underneath a ring, but often caused worse swelling if it was under the ring and close to the foot.
Figure 4.
Injuries on Brown Thornbill legs caused by plastic colour ring in upper position.
Since Brown Thornbills in Tasmania often forage hanging upside down, the plastic ring is pushed onto the tibo-tarsal joint, causing a severe infection in 3% of birds, and loss of a foot in 1%. This individual was initially colour ringed on 13 December 2010, and recaptured to remove the colour rings on 9 April 2011.
Figure 5.
Brown Thornbills with damaged aluminium rings which have been mounted on top of each other.
Individual a) was ringed in September 2007 and re-captured the beginning of October 2008 to remove the aluminium rings and mount plastic split rings instead. The bird was still alive in August 2012.
Table 3.
Proposed ringing hazard categories.
Table 4.
Overview of non-plastic alternatives to colour rings.