Molting while breeding? Lessons from New World Tyrannus Flycatchers

JAHN, ALEX E.; BEJARANO, VANESA; GUZMÁN, MARCELA BENAVIDES; BROWN, LEONE M.; CARVALHO PROVINCIATO, IVAN C.; CEREGHETTI, JOAQUÍN; CUETO, VÍCTOR R.; GIRALDO, JOSÉ I.; GÓMEZ-BAHAMÓN, VALENTINA; HUSAK, MICHAEL S.; LEPAGE, HEATHER K.; MACPHERSON, MAGGIE; MARINI, MIGUEL ÂNGELO; PIZO, MARCO AURELIO; QUICKLE, AARON; ROEDER, DIANE V.; SARASOLA, JOSÉ HERNÁN; TUERO, DIEGO T.

Journal of Ornithology

Springer

Año: 2017

2193-7192

Abstract.-Songbirds must annually undergo two energetically demanding but importantactivities: breeding and feather molt. Due to the high energetic investmentthat each demands, these two events are generally not carried outsimultaneously. However, substantial variation in annual reproductiveinvestment among populations may result in variation in molt-breeding overlapbetween them. With the goal of understanding whether and how different songbirdpopulations overlap molt and breeding, and to determine directions for researchon the potential tradeoffs involved, we describe the relationship between clutchsize, molt, and energetic condition within a genus of New World flycatchers (Tyrannus). Of 219 flycatchers sampled,only one individual molted flight feathers while breeding, suggesting thatmolting flight feathers and breeding simultaneously is too energeticallyexpensive at any clutch size. However, we found a significant negativerelationship between clutch size and the intensity of body molt in male but notfemale flycatchers. When we tested for an effect of clutch size, sex andenergetic condition on body molt intensity during the breeding season, onlyclutch size and sex had significant effects, with a negative effect of clutchsize on body molt intensity in males but not females. Based on these results,we develop a set of hypotheses to guide future studies on the potentialtradeoffs between investing in reproduction and molt.