Predator Exclusion Methods for Managing Endangered Shorebirds: Are Two Barriers Better than One?

Publication Type:Journal Article
Year of Publication:2003
Authors:Murphy1, RK, Greenwood2, RJ, Ivan3, JS, Smith4, KA
Journal:Waterbirds
Volume:26
Issue:2
Date Published:2003
ISBN Number:1524-4695
Keywords:Charadriidae, Charadrius, Charadrius melodus
Abstract:Abstract Reproductive success of shorebirds can be improved by placement of predator exclosure fences along beaches or wire-mesh exclosure ?cages? over nests. We predicted that these two types of exclosures used simultaneously might further improve reproductive success over that when cages alone are used. Field experiments were carried out on Piping Plovers (Charadrius melodus) on prairie alkali lakes in North Dakota and Montana. During 1996 and 1997, we compared success of nesting plover pairs provided with: (1) no protection, (2) cages that protected eggs in individual nests from both mammalian and avian predators, and (3) a combination of cages plus a temporary electric fence that excluded mammalian predators from the entire nesting beach where chicks were being reared. In 20 replicated trials, fledgling production rates were: no protection, 0.72 chicks/pair (95% CI: 0.29-1.15, N = 43 pairs); cage only, 1.73 (1.30-2.16, N = 46); fence plus cage, 2.06 (1.63-2.49, N = 50). Production by protected pairs was significantly greater than for unprotected pairs. However, no significant difference in production was detected between the two protection types. Temporary electric fences were relatively expensive to apply and added little to the effectiveness of cages, but may be appropriate in situations where cages cannot be used or where mammalian predation on chicks is a greater threat.Abstract Reproductive success of shorebirds can be improved by placement of predator exclosure fences along beaches or wire-mesh exclosure ?cages? over nests. We predicted that these two types of exclosures used simultaneously might further improve reproductive success over that when cages alone are used. Field experiments were carried out on Piping Plovers (Charadrius melodus) on prairie alkali lakes in North Dakota and Montana. During 1996 and 1997, we compared success of nesting plover pairs provided with: (1) no protection, (2) cages that protected eggs in individual nests from both mammalian and avian predators, and (3) a combination of cages plus a temporary electric fence that excluded mammalian predators from the entire nesting beach where chicks were being reared. In 20 replicated trials, fledgling production rates were: no protection, 0.72 chicks/pair (95% CI: 0.29-1.15, N = 43 pairs); cage only, 1.73 (1.30-2.16, N = 46); fence plus cage, 2.06 (1.63-2.49, N = 50). Production by protected pairs was significantly greater than for unprotected pairs. However, no significant difference in production was detected between the two protection types. Temporary electric fences were relatively expensive to apply and added little to the effectiveness of cages, but may be appropriate in situations where cages cannot be used or where mammalian predation on chicks is a greater threat.
URL:http://dx.doi.org/10.1675/1524-4695(2003)026[0156:PEMFME]2.0.CO;2
Short Title:Waterbirds
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith