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

Waterfowl managers are concerned that Lesser Scaup (Aythya affinis) breeding populations remain below conservation goals. Contrasting population growth trajectories for sympatric, phylogenetically similar and Ring-necked Duck collaris) at Erickson, Manitoba, Canada, prompted investigations might help explain these trends provide insight management of both species. We collected data (2008–2018) on productivity (broods/pair), water levels, hatching dates, age class-specific brood sizes, duckling daily survival rate, female response to disturbance compared results between species over time. was greater (0.42 versus 0.28, P &lt; 0.01), dates were earlier (19 July 27 July, 0.001), females attempted hide their broods more often than did (16% 3%, but sizes smaller (Ia broods: 6.1 6.8, = 0.02; IIa 5.6 6.2, 0.02). Duckling rates similar. Productivity positively related annual change in pond level demonstrated change. There no support an association one- or two-year lagged levels. Consistent with previous findings, our suggest is a likely proximate cause the differing better nest placement may be contributing factor success observed.