Evening Flights of Female Northern Pintails from a Major Roost Site

Abstract

We monitored evening flights of female Northern Pintails (Anas acuta) from Lacassine National Wildlife Refuge (NWR) in southwestern Louisiana during winters of 1991-1992 and 1992-1993. We analyzed the influence of female age, winter, and date within wintering period on three flight parameters: distance, duration, and departure time. Flight distance and duration increased with date within wintering period, and age differences in flight distance and duration were not consistent between winters. Females departed 12 min later, on average, on clear, moonlit evenings than on overcast, moonless evenings, and 4 min later when winds were light rather than heavy. After controlling for variation due to environmental conditions, immature females departed Lacassine NWR 1.3 min earlier, on average, than did adults. Flight parameters of females did not differ between hunting and non-hunting time periods. Estimated daily transit costs ranged from 27-54% of basal metabolic rate, 7-19% of daily energy expenditure, and 8-20% of daily dietary intake of rice (Oryza sativa). Our findings that flight distance and duration increased with date within wintering period were consistent with predictions of refuging theory, but alternative hypotheses also could explain these results. Evening flights of Northern Pintails roosting on Lacassine NWR were greater in distance and duration than those reported for most other species of wintering waterfowl. We recommend that proximity of refuges to feeding sites be considered in conservation and management plans for wintering Northern Pintails and other refuging waterfowl.

Foraging flight distances of wintering ducks and geese: a review

“…Food resources within functional units can be estimated to gauge energetic carrying capacity (Pearse et al 2010). Predictions about spatial and seasonal resource use within functional units are consistent with "refuging" theory (Hamilton and Watt 1970), which posits that foods closer to roost sites will be utilized and depleted first, forcing ducks and geese to radiate further from roosts to meet their energetic demands as the season progresses (Frederick et al 1987, Cox and Afton 1996, Gill 1996. Energy expenditure and daily energy budgets are affected by distance of foraging flights (Pearse et al 2010), as is the givingup density, or the point at which food depletion makes it no longer profitable to feed in a given field (van Gils and Tijsen 2007).…”

“…‡ Cox and Afton (1996) found differences between first winter and adult birds. § Y = Yes ("evidence" was found); N = No ("evidence" was not found).…”

“…Because FFD information was ancillary to the primary objective of most studies we reviewed, informative tests on sex, age, roost size, forage habitat type, or seasonal effects, i.e., changes in distances flown as seasons progress (Hamilton andWatt 1970, Cox andAfton 1996), were seldom performed. When significant differences between age cohorts or year were reported (e.g., Afton 1996, Link et al 2011), these FFD values were considered to be independent and were included in our review and subsequent analyses.…”

“…Although foraging flights are common in waterfowl that exploit agricultural crops, such as dabbling ducks and geese (Baldassarre andBolen 1984, Vickery andGill 1999), waterfowl also make foraging flights to browse on pasture, meadow, and submerged aquatic vegetation, and to feed in freshwater wetlands and coastal waters (Morton et al 1989, Howerter 1990, Vickery and Gill 1999, Merkel et al 2006. Distances flown between roost sites and foraging areas may be influenced by the proximity of habitats (Frederick et al 1987, Cox and Afton 1996, Davis and Afton 2010, food availability (Cox and Afton 1996, Gill 1996, Link et al 2011, disturbance (Austin and Humburg 1992, Moon 2004, Fleskes et al 2005, type of foraging habitat (Hill and Frederick 1997), temperature/weather (Jorde et al 1983, Baldassarre and Bolen 1984, Legagneux et al 2009), body size (Mini 2012), social status of individual birds (Morton et al 1989, Cox andAfton 1996), and other factors. Legagneux et al (2009) noted that wintering dabbling ducks in North America appear to make longer foraging flights than those in Europe and suggested this may be related, in part, to the abundance of waterfowl concentrated at wintering areas; they speculated that longer foraging flights might be associated with larger bird densities, high demand for and high use of food resources caused by those densities, and also potential habitat characteristics such as distances between roost sites and feeding sites.…”

Lead isotope ratio measurements as indicators for the source of lead poisoning in Mute swans (Cygnus olor) wintering in Puck Bay (northern Poland)

“…Although using blood samples allows an assessment of Pb sources for about a month prior, the lack of data on migratory schedule between breeding and wintering sites makes the interpretation of obtained results problematic. Even in wintering grounds, some wildfowl species make regular movements up to 40-50 km using different foraging areas during the day and at night (Cox and Afton, 1996;Jorde et al, 1983;Link et al, 2011), and this should also be taken into account in studies designed to recognise sources of Pb pollution. Hence, isotopic measurement seems to be good method for use in biomonitoring studies, but in the case of migratory populations of birds, a more detailed interpretation of obtained results is difficult due to unknown origin and migration schedule of individuals from a given population.…”