Action: Use multiple barriers to protect nests
Key messagesRead our guidance on Key messages before continuing
- A replicated, controlled study from the USA found no evidence that erecting an electric fence around nests protected by individual barriers increased fledging success in piping plovers Charadrius melodus.
- A replicated study from the USA found that removing the outer of two nest protection fences after 15 days appeared to reduce predation compared to when both fences were left for 18 days.
Supporting evidence from individual studies
A replicated, controlled study in 1996 and 1997 at three alkali lakes in North Dakota and Montana, USA (Murphy et al. 2003) found that piping plover Charadrius melodus fledging rates were higher with mesh fences erected around individual nests (see ‘Physically protect nests with individual exclosures/barriers’). When an electric fence (1.1 m tall) was erected around study sites there was a non-significant increase in fledging success, compared with sites where only individual nest fences were used (2.1 chicks/pair with electric fence and nest fences, n = 50 vs. 1.7 chicks/pair with only nest fences, n = 46).
A replicated study from 2001-2002 at three black tern Chlidonias niger colonies in wetlands in Maine, USA (Heath & Servello 2008) found that surrounding nests with both a chick retention fence and a predator exclosure fence but removing the chick retention fence 15 days after hatching in 2002 appeared to reduce predation (three chicks from one nest predated, n = 33 chicks from 14 nests), compared to when the retention fence was left until chicks were 18 days old in 2001 (17 chicks from seven nests predated, n = 36 chicks from 14 nests). The chick retention fence was 30 cm high and 15 cm off the ground, and consisted of a 1 m diameter circular fence with an overhead ‘concealment flap’ of wire covered in landscaping cloth; the predator exclosure fence was 1.4 m high and 4.6 m in diameter. The study did not include control (unprotected) nests, so the overall effectiveness of the fences cannot be judged. This study also discussed nest abandonment; see ‘Can nest protection increase nest abandonment?’
- Murphy R.K., Greenwood R.J., Ivan J.S. & Smith K.A. (2003) Predator exclusion methods for managing endangered shorebirds: are two barriers better than one? Waterbirds, 26, 156-159
- Heath S.R. & Servello F.A. (2008) Effects of predation and food provisioning on black tern chick survival. Wilson Journal of Ornithology, 120, 167-175