Rookeries Show Big Increases in Nest Sites
at Restored Will County Preserve

All four species of nesting birds at Lake Renwick Heron Rookery Nature Preserve in Plainfield showed gains this year in the first full breeding season since restoration work was completed by the Forest Preserve District of Will County.

Counts taken in May and June on the two breeding islands in the middle of the lake revealed that black-crowned night-heron nests increased from 39 nests to 92. These nests account for an estimated 15 percent of the total statewide breeding population of the state-endangered bird.

Great blue heron nest sites increased to 266, compared to last year's 184; great egret nest sites increased to 362, up from 324 last year; and double-crested cormorant nests increased to 489, an increase from 397.

Because each of the species that nests on the islands has different requirements, 561 new nesting sites were created. These consisted of artificial trees, pole structures, log piles, nesting boxes, and live vegetation. The large construction project was completed in late winter of this year, just as the birds were returning to the islands from their winter migration.