Different Lineages, Shared Strategies: Trail Cameras Reveal Similar Incubation Behavior in Wood Ducks and Hooded Mergansers in Louisiana and Mississippi

Incubation behavior reflects how birds balance the thermal needs of developing embryos against their own requirements for self-maintenance, with consequences for nest survival and hatching success. This behavior is expected to vary among species based on evolutionary history and life-history strategies. We used motion-activated trail cameras to compare incubation-recess behavior of 2 cavity-nesting ducks, a perching duck (Aix sponsa [Wood Duck]) and a sea duck (Lophodytes cucullatus [Hooded Merganser]), both using nest boxes in Louisiana and Mississippi. Despite differences in life history and foraging ecology between perching- and sea-duck guilds, the species exhibited broadly similar nest attentiveness. Wood Ducks averaged 2.55 ± 0.58 recesses per day, and Hooded Mergansers averaged 2.49 ± 1.12 recesses per day, and daily incubation constancy was similar (87.1% vs. 86.9%). In contrast, recess timing differed consistently between species. Wood Ducks initiated morning recesses earlier (06:54 ± 0.58 h) than Hooded Mergansers (09:01 ± 0.76 h), whereas Hooded Mergansers tended to recess earlier in the afternoon (15:18 ± 0.40 h) than Wood Ducks (16:19 ± 1.12 h). Within species, Wood Duck morning recess duration decreased with increasing clutch size (-7.9 ± 2.9 min/egg), while Hooded Merganser morning recess duration declined across incubation (-5.6 ± 1.9 min/ day). Overall, the clearest divergence between species occurred in recess timing rather than the intensity of incubation behavior.