Description of Monitoring
Each year, the rookery comes alive with the cacophony of nesting herons, egrets, and cormorants and their rowdy offspring. Volunteers and ESNERR staff have been monitoring the rookery for over a decade. We track abundance of adults and active nests for the three breeding species, track their reproductive timing, estimate reproductive success, and assess colony impacts to the trees they use.

Objectives
The size and success of this rookery is likely related in part to the quality of wetland habitats in the area. Indeed, the rookery first became established shortly after the restoration of nearby wetlands which provide a rich source of invertebrate and fish prey for both parents and their offspring. We track the rookery size and success as one indicator of the health of our wetlands. We also monitor the timing of reproduction which may be useful for tracking interannual climatic variation or long-term climate trends.

Results thus far
The rookery has been monitored since 1985. General trends in the data include a decrease in herons, increase in cormorants, and fairly steady numbers of egrets over time. The species vary in their reproductive timing. The trees they use are killed by guano cover within only a few years of colonization. The results of rookery monitoring from 1985-2001 are available as a summary report. Click here to view this report as a .pdf file (99KB).

How to get involved
If you are interested in carrying out rookery monitoring, contact Kerstin Wasson ( ). This involves walking our South Marsh Loop trail at least twice a month between March and August, on your own, and carefully filling out a data sheet with counts of adults and nests and assessments of behaviors. We will also be carrying out two team surveys, in June and in August, to assess reproductive success nest by nest. Contact Kerstin if you are interested in signing up for these events.