Oddity and Specific Searching Image more Important than Conspicuousness in Prey Selection

How do different releasing techniques affect the survival of reintroduced grey partridges Perdix perdix?

“…Negative effects may be caused by: 1) decreasing breeding success of wild birds that pair with reared birds (Rands & Hayward 1987), 2) attracting predators (Kenward 1981, Robertson 1988) and enhancing their interest in catching galliforms instead of other prey (Mueller 1971, Costantini et al 2005); however, DeVos & Speake (1995) did not find increased mortality of wild bobwhites after the release of artificially reared birds, 3) degrading genetics (Sage et al 2001, Ford 2002, Meriggi et al 2002, 4) genetic pollution (Barbanera et al 2007, Barilani et al 2007, Puigcerver et al 2007, and 5) increasing prevalence of parasites (Milla´n et al 2004, Villanua et al 2008. The use of medication in reared stocks may leave birds immunologically vulnerable when challenged by pathogens in the wild (Dowell 1992).…”

Field Experiments On the Adaptive Significance of Avian Eggshell Pigmentation

“…The effects (functions) of this behaviour (TINBERGEN, 1963(TINBERGEN, , 1973BEER, I973b), if any (WILLIAMS, 1966), have not been investigated, but the present expression of the behaviour pattern indicates that predation pressures have not strongly selected against it. The visual search image strategies (CROZE, 1970;MUELLER, 1971;KREBS, 1973;PAULSON, 1973;SLOAN & SIMMOrrs, 1973) of avian egg and chick predators hunting in coastal seabird nesting regions may exclude bright or white items on the ground. The natural and artificial eggshell "camouflage" studied in the present experiment may have been more representative of the crows' usual egg prey.…”

Size assortment in mixed-species groups of juvenile-phase striped parrotfish (Scarus iserti) in The Bahamas

“…The relative rarity of S. iserti groups containing only one or two heterospecific associates may relate to avoiding relatively high rates of predation by being clearly different from other group members (Mueller 1971 ). Wolf (1985 ) found that stoplight parrotfish (Sparisoma viride ) and ocean surgeonfish (Acanthurus bahianus ) in S. iserti groups left the group sooner if it had relatively few conspecific group members.…”

“…Homogeneous schools can reduce predation rates on individuals by increasing the predator confusion effect (Mueller 1971 ), as it may become increasingly difficult for a predator to single out a group member as the number of individuals increases, especially if the members are phenotypically similar (e.g., Landeau and Terborgh 1986 ). Competition for resources among group members may also lead to such assortment, with small individuals avoiding larger individuals to decrease competition (Krause et al 1996).…”

“…This preferred uniformity promotes the antipredatory response commonly known as the ''confusion effect'' and reduces the ''oddity effect'' (Mueller 1971), in which a phenotypically dissimilar individual in a group may be more likely to be targeted by predators (e.g., Landeau and Terborgh 1986;Theodorakis 1989). For S. iserti, however, the common, heterospecific associates often differ greatly in color and body shape (Wolf 1985).…”