Erickson Study Area: Duck Breeding Populations and Habitat, Then (1970-72) and Now (2008-13)

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“…The intensively studied areas constitute a block (6.8 km²) and a roadside transect (21.7 km long and 400 m on either side of the road) established 4.0-12.5 km to the southeast in 2009 and collectively constitute an area of 22.6 km² (hereafter the primary study area, see Hammell 2016 for map). The 2009-2018 transect was established to increase pair and brood sample sizes as preliminary data collection in 2008 indicated that the Lesser Scaup breeding population on the block (19-23 pairs, 1970) had decreased significantly (two pairs, 2008Hammell 2014). In 2008-2018, the block contained about 141 wetlands: 53 class I and 50 class II, 10 class III, seven class IV, and 21 class V; size range ≤0.1-11.5 ha (Stewart and Kantrud 1971).…”

“…The annual Breeding Waterfowl Population Survey suggests the Ring-necked Duck continental population is stable or increasing but that the combined continental population of Lesser and Greater Scaup (Aythya marila: counted together on surveys) has declined from highs of five to seven million birds in the 1970s to three to five million in the past decade, ~20% below the North American Waterfowl Near a long-term waterfowl study area in southwestern Manitoba, the Lesser Scaup breeding population has declined from the early 1980s to about 2000 when numbers appear to have stabilized. In contrast, Ring-necked Duck breeding density has increased dramatically from the 1970s (Koons and Rotella 2003a;Hammell 2014Hammell , 2016; Figure 1). Such distinctive long-term population trends for these phylogenetically and morphologically similar species affords testing of hypotheses regarding species difference in reproductive metrics.…”

Comparative reproductive parameters of sympatric Lesser Scaup (<i>Aythya affinis</i>) and Ring-necked Duck (<i>Aythya collaris</i>) in parkland Manitoba

“…The intensively studied areas constitute a block (6.8 km²) and a roadside transect (21.7 km long and 400 m on either side of the road) established 4.0-12.5 km to the southeast in 2009 and collectively constitute an area of 22.6 km² (hereafter the primary study area, see Hammell 2016 for map). The 2009-2018 transect was established to increase pair and brood sample sizes as preliminary data collection in 2008 indicated that the Lesser Scaup breeding population on the block (19-23 pairs, 1970-1972) had decreased significantly (two pairs, 2008;Hammell 2014). In 2008-2018, the block contained about 141 wetlands: 53 class I and 50 class II, 10 class III, seven class IV, and 21 class V; size range ≤0.1-11.5 ha (Stewart and Kantrud 1971).…”

“…In 2008-2018, the block contained about 141 wetlands: 53 class I and 50 class II, 10 class III, seven class IV, and 21 class V; size range ≤0.1-11.5 ha (Stewart and Kantrud 1971). Relative to other agricultural areas of Manitoba, the study site has changed little in wetland area or upland use from the early 1970s (Hammell 2014). During a record wet year in 2011, several permanent ponds (class V) joined to form several larger wetlands (largest 21.7 ha).…”

“…Near a long-term waterfowl study area in southwestern Manitoba, the Lesser Scaup breeding population has declined from the early 1980s to about 2000 when numbers appear to have stabilized. In contrast, Ring-necked Duck breeding density has increased dramatically from the 1970s (Koons and Rotella 2003a;Hammell 2014Hammell , 2016; Figure 1). Such distinctive long-term population trends for these phylogenetically and morphologically similar species affords testing of hypotheses regarding species difference in reproductive metrics.…”