The Virginia Tech Roseate Tern (Sterna dougallii; ROST) study is a collaborative project with managers and researchers from Cape Cod National Seashore (CACO), Mass Audubon Coastal Waterbird Program (MACWP), the State University of New York College of Environmental Science and Forestry, and the USGS. The Virginia Tech portion of the study will attempt to determine the effects of disturbance, including human activities and natural events, during the fall pre-migratory staging period on parent-offspring interactions and hatch-year (HY) ROST survival.
The Northwest Atlantic (NWA) population of ROSTs was listed as endangered in 1987 and has been intensively managed and monitored on the breeding grounds since then; however, little is known about their activities after they leave the breeding sites. This population of ROSTs has declined by 25% since 2000 despite relatively good productivity and constant adult survival. Studies have suggested that most mortality of ROSTs takes place away from breeding sites (Nisbet and Spendelow 1999), during staging/migration or in wintering quarters. However, little information is available about causes of death or even sub-lethal effects/stressors during these periods.
Nearly the entire NWA population of ROSTs is thought to stage at CACO, MA before departing for their fall migration to South America. Preliminary data on disturbance at CACO (collected before the genesis of this current project) suggest that staging ROST are exposed to multiple types of human activities, including dogs, pedestrians, automobiles, ATVs, and kayaks (MACWP 2012). These disturbances often result in staging flocks being flushed from resting areas. Depending on the size of the flocks, these events could result in thousands of birds rapidly taking flight simultaneously and possibly leaving the area, which may lead to the separation of parents and fledglings. Based on previous studies and anecdotal evidence, we hypothesize that survival of HY ROSTs is dependent on receiving parental care. Roseate Terns exhibit post-fledging brood and care division (Watson et al. 2012)—in other words, adults continue to care for their offspring long after the chicks have fledged. Factors lowering the amount and/or rate of food provided by the care-giving parent, for instance parent-offspring separation, during the pre-migratory staging period might result in an increased probability of HY mortality, if not during the staging period, then possibly during migration.
Considering that high proportions of the NWA breeding population may depend on CACO during the staging period (Jedrey et al. 2010), there is a critical urgency to understand the factors affecting survival, particularly of the HY birds. By focusing on disturbance at CACO, our study will be able to suggest ways to minimize and mitigate disturbance to this endangered species and dozens of additional species of terns and shorebirds.
Jedrey, E.L., R.J. Harris, and E.A. Ray. 2010. Roseate Terns – citizens of the world: the Canada to Cape Cod connection. Bird Observer 38:146-150.
MACWP [Mass Audubon Coastal Waterbird Program]. 2012. Appendix 3: Characterization of Disturbance to Roseate and Common Tern Flocks, southeast Massachusetts 2008. 2012 Roseate Tern Resighting Report. Mass Audubon Coastal Waterbird Program.
Nisbet, I. C. T., and J. A. Spendelow. 1999. Contribution of research to management and recovery of the roseate tern: review of a twelve-year project. Waterbirds 22: 239-252.
Watson, M.J., J.A. Spendelow, and J.J. Hatch. 2012. Post-fledging brood and care division in the Roseate Tern (Sterna dougallii). Journal of Ethology 30:29-34.