Presence of fish affects lake use and breeding success in ducks

Abstract

Several previous studies indicate that presence of fish has negative effects on waterbirds breeding on lakes, owing either to competition for common invertebrate prey or fish predation on ducklings/chicks. However, others have reported results to the contrary and it remains unresolved what factors trigger, inhibit, and modulate fish-waterbird interactions. The present study was designed to test the effect of fish presence per se, with a minimum of variation in possibly confounding environmental variables. Thus, after stratifying for area, depth, altitude, pH, and total phosphorus we compared 13 lakes with and 12 without fish (mainly pike Esox lucius and perch Perca fluviatilis) with respect to (i) general species richness of waterbirds, (ii) species-specific utilization and breeding success of two dabbling ducks (mallard Anas platyrhynchos and teal Anas crecca) and a diving duck (goldeneye Bucephala clangula). General species richness of waterbirds was higher on fishless lakes. Overall use (bird days) and brood number of teal and goldeneye were higher on fishless lakes. The latter also had more benthic and free-swimming prey invertebrates compared to lakes with fish. Mallard use, mallard brood number, and abundance of emerging insects did not differ between lake groups. Generalized linear models including fish presence as factor and considering seven environmental variables as covariates, confirmed that all waterbird variables except mallard days and broods were negatively correlated to fish presence. There was also a residual positive relationship of lake area on general species richness, teal days, and teal broods. Our data demonstrate a stronger effect of fish presence on diving ducks and small surface feeding ducks than on large surfacefeeding ducks. We argue that observed patterns were caused by fish predation on ducks rather than by fishduck competition for common prey.

Competitive effects of fish in structurally simple habitats: perch, invertebrates, and goldeneye in small boreal lakes

“…Among vegetation, the effect of fish predation on invertebrates is not as pronounced (Gilinsky 1984;Diehl 1992;Nummi et al 2006). And dabbling ducks, such as mallard (Anas platychynchos), which forage among shoreline vegetation, are not as strongly affected by fish (Eriksson 1983;Elmberg et al 2010). In more eutrophic lakes, other fish species, such as roach, may be more common than perch (Olin et al 2002;Rask et al 2010).…”

Foraging guild membership explains variation in waterbird responses to the hydrological regime of an arid‐region flood‐pulse river in Namibia

“…Predation, conversely, may be expected to act against more vulnerable species regardless of their foraging guild, again obscuring any guild-related responses to hydrology. Although there has again been relatively little research on predation impacts on waterbird communities in southern Africa, evidence from other locations suggests that predators can have a major impact on ground-and reed-nesting waterbirds (Erwin, Truitt & Jiménez, 2001;Elmberg, Dessborn & Englund, 2010) and crocodiles, monitor lizards, mongooses, snakes and large fish are common in our study site. There is also good evidence from other locations that non-piscivorous waterbirds may compete with fish for invertebrate prey (Haas et al, 2007) and that density dependence can regulate breeding success in ducks (Elmberg et al, 2005).…”

Pike predation affects breeding success and habitat selection of ducks

“…Each lake was surveyed twice (in the period May and August) between 1999 and 2005 as a part of a study by Elmberg et al. (2010).…”

“…Within an area of roughly 500 km 2 and comprising of many catchments, we selected 11 naturally fishless lakes that had been part of a previous descriptive study (Elmberg, Dessborn & Englund, 2010). A before-after control-impact design was used to quantify the effects of pike on the occurrence and breeding success of ducks.…”