The post-fledging period in a tropical bird: patterns of parental care and survival


  • Corey E. Tarwater,

  • Jeffrey D. Brawn

C. E. Tarwater ( and J. D. Brawn, Progr. Ecol., Evol. and Conserv. Biol., Univ. of Illinois at Urbana-Champaign, 606 E. Healey St., Champaign, IL 61820, USA. JDB also at: Dept. of Nat. Res. and Environm. Sci., Univ. of Illinois at Urbana-Champaign, 503 Turner Hall, 1102 Goodwin Ave, Urbana, IL 61801, USA. Present address of JDB: Dept. of Nat. Res. and Envir. Sciences, University of Illinois at Urbana-Champaign.


How environmental conditions affect the timing and extent of parental care is a fundamental question in comparative studies of life histories. The post-fledging period is deemed critical for offspring fitness, yet few studies have examined this period, particularly in tropical birds. Tropical birds are predicted to have extended parental care during the post-fledging period and this period may be key to understanding geographic variation in avian reproductive strategies. We studied a neotropical passerine, the western slaty-antshrike Thamnophilus atrinucha, and predicted greater care and higher survival during the post-fledging period compared to earlier stages. Furthermore, we predicted that duration of post-fledging parental care and survival would be at the upper end of the distribution for Northern Hemisphere passerines. Correspondingly, we observed that provisioning continued for 6–12 weeks after fledging. In addition, provisioning rate was greater after fledging and offspring survival from fledging to independence was 75%, greater than all estimates from north-temperate passerines. Intervals between nesting attempts were longer when the first brood produced successful fledglings compared to nests where offspring died either in the nest or upon fledging. Parents delayed initiating second nests after the first successful brood until fledglings were near independence. Our results indicate that parents provide greater care after fledging and this extended care likely increased offspring survival. Moreover, our findings of extended post-fledging parental care and higher post-fledging survival compared to Northern Hemisphere species have implications for understanding latitudinal variation in reproductive effort and parental investment strategies.