Black Tern (Chlidonias niger) Nest Success and Incubation Behavior in Northern Michigan, United States

Abstract

Nest success and chick survival are difficult to determine in Black Terns (Chlidonias niger) due to cryptic nests and chicks, challenging to access nest locations, and potential detrimental effects on nest success from increased disturbance in the colony. Nest success and attendance rates were documented in a Black Tern colony in northern Michigan, USA, in 2017 and 2018 using nest cameras and weekly site visits to overcome these challenges. Nest success was estimated at 74% (95% CI = 41%-91%) in 2017 and 81% (95% CI = 61%-92%) in 2018. Mean nest attendance during the late incubation stage (86%) was significantly higher than during the early stage (77%); and time of day had a significant effect on nest attendance rates, with adult Black Terns spending more time on the nest at night. When chicks reached 6 days post-hatch, mean diurnal nest attendance dropped to 35% or lower. Nocturnal nest attendance remained high until the chicks were 6 or more days old, then nest attendance declined precipitously. These findings may provide further insight into the use of nest cameras and potential factors limiting Black Tern nest success and chick survival in the Great Lakes.