Timing of nesting of upland-nesting ducks in the Canadian prairies and its relation to spring wetland conditions

Abstract

Timing of breeding varies among waterfowl species and individuals, with strong effects on reproductive success, and may be related to habitat quality. Here, we analyse the start, span, and end of the nesting season for nine upland-nesting duck species at 166 Canadian Prairie–Parkland sites over 34 years to better characterize nesting patterns and test whether and how species respond to May pond abundances. Nesting metrics were compared between single-site versus multiple-site studies over 7 years to evaluate the effects of spatial scale and methodology. Strong, consistent differences in start of nesting were found among duck species, being earliest for Northern Pintail (Anas acuta L., 1758) and Mallard (Anas platyrhynchos L., 1758), followed by Northern Shoveler (Anas clypeata L., 1758), American Green-winged Teal (Anas crecca carolinensis Gmelin, 1789 = Anas carolinensis Gmelin, 1789), Blue-winged Teal (Anas discors L., 1766), American Wigeon (Anas americana Gmelin, 1789), Gadwall (Anas strepera L., 1758), and lastly by Lesser Scaup (Aythya affinis (Eyton, 1838)) and White-winged Scoter (Melanitta fusca deglandi (Bonaparte, 1850)). Span and end of nesting were related to May pond abundances, but the strength of these relationships varied among species, presumably reflecting the flexible (re-)nesting potential of individuals of some species in response to wetland-habitat quality.