Least Bittern Juvenile Movements and Habitat Use at Emiquon Preserve

Least Bitterns (Ixobrychus exilis) are secretive marsh birds that are migrants and residents of Illinois. They are a state threatened species that resides primarily in inundated cattail marsh. Emiquon Preserve is a restored wetland along the Illinois River and through water-level manipulations it produces heterogeneous habitats and is home to breeding Least Bitterns. There is limited knowledge about Least Bittern juvenile habitat use and movement before flight is attained, and this information would be beneficial for management for this species. This project aimed to understand how juvenile Least Bitterns use their habitat as they mature and how water management may impact habitat-use decisions. From June through August 2020 we hand-captured unflighted juvenile Least Bitterns at known nests with known ages. All handled birds were banded and those within an appropriate weight range were given glued-on VHF tags. Juveniles were tracked every 1-4 days through homing techniques. Once visually located, locations, percent aerial visibility, dominant vegetation type, and habitat were recorded. This study presents the relationships between age and dispersal from the nest as well as flight capability (flighted at day 29) and habitat use.