Penning, W.L. 1993. The common tern (Sterna hirundo) in western Lake Superior: history, management, and population modeling. M.S. Thesis, University of Minnesota. 59 pp.
This thesis is divided into two parts: (1) a history of colonial waterbird management in the St. Louis River estuary, and (2) a predictive model for Common Tern populations.
The first part summarizes the history and methods of management of Common Terns in the estuary (1937 - 1990). Human disturbance, predation and gull encroachment were identified as primary reasons for breeding failure. Availability of nesting habitat free from human disturbance, predators and competition from gulls appears to be the most important factor influencing breeding productivity.
Population dynamics of Common Terns were explored using a deterministic model. Variables defining a stable breeding population examined included: (1) sub adult survival rate (2) adult survival rate (3) adult reproductive rate (Mx) and (4) sub adult reproductive rate.
This model suggests a realistic combination of variables needed to maintain a stable population is: Mx = 1.10, adult survival = 92%, sub adult survival = 15%, and sub adult breeding = 12.5%.