Great egrets and double-crested cormorants at the rookery in the middle of Baker's Lake. (Forest Preserve District of Cook County / Facebook)

The deaths occurred at the Baker’ s Lake forest preserve, the Forest Preserves of Cook County said in a statement on Thursday.

Artist John Bannon works on his tree sculpture “Y Knot” on March 4, 2022, in Hollywood Park as part of the Chicago Tree Project program. (WTTW News)

The overall number of trees in the region has increased, according to a 2020 tree census conducted by Morton Arboretum.  But not all trees are seen as equals. Some are invasive and prevent native trees and plants from flourishing. 

Wildlife biologists band egrets at Baker’s Lake. (Forest Preserve District of Cook County)

Cook County’s forest preserves are much loved for their picnic groves and trails. Not as well known: The forest preserve district’s role as a research hub and early warning system of sorts against zoonotic diseases.

North American river otters, once nearly extinct in Illinois, are a great comeback story. (Grayson Smith / U.S. Fish and Wildlife Service)

The Urban River Otter Research Project recently launched in Cook County. One of the early goals is to gather otter sightings from the public in order to get a sense of the extent of the animal’s presence in and around Chicago.

(Patty Wetli / WTTW News)

In honor of Monday’s Martin Luther King Day of Service, Cook County Forest Preserves is hosting volunteer activities at a number of sites across the forest preserve district, from habitat restoration to litter cleanups.

A falconry hood is placed over the eagle's eyes and ears to help relax the bird and make the exam easier on the bird and handlers. (Courtesy of Willowbrook Wildlife Center)

Eagles don't eat rat poison, but they do eat the critters that take the bait. The powerful toxins keep blood from clotting, and a recently rescued eagle would have bled to death from a tiny cut, said the veterinarian caring for the bird. 

Shedd Aquarium's Maggie Cooper demonstrates proper sawing technique during a work day at Skokie Lagoons. (Patty Wetli / WTTW News)

Skokie Lagoons may look like an oasis of green but a lot of that lush vegetation is actually an invasive species called European buckthorn. WTTW News tagged along as a group of volunteers charged into the thicket and tackled this enemy. 

The Forest Preserve District of Cook County encompasses nearly 70,000 acres. (Patty Wetli / WTTW News)

The recommended 2022 budget will keep the doors open and the lights on, but doesn’t make a dent in the district’s $64 million in unfunded maintenance, pension obligations or goal to acquire more land. For those resources, the district is pinning its hopes on an upcoming property tax referendum.

If marsh birds like the pied-billed grebe, pictured, return to Powderhorn Lake, conservationists will judge the wetlands restoration a success. (simardfrancois / Pixabay)

A wetlands restoration project is underway at Powderhorn Lake Forest Preserve in the Calumet region, where construction of a human-made water control device will recreate a more natural system of drainage.

One of the 2020 photo contest winners, taken at Oak Forest Heritage Preserve. (Credit: Sharon Dobben)

Dig those images of flowers, birds and trees out of the iCloud and enter them in the forest preserve district’s annual photo contest. Winning images will be featured in the district’s 2022 calendar. 

Chicago as seen from the International Space Station. The Palos Preserves Urban Night Sky Place is outlined in green. (Courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center)

Palos Preserves has been named an Urban Night Sky Place by the International Dark-Sky Association. The site emits nearly 1,000 times less light than downtown Chicago, with four times as many stars visible in the night sky than can be seen in the city.

Spring Lake Forest Preserve, Cook County. (Patty Wetli / WTTW News)

How much is nature worth? The Forest Preserve District of Cook County is about to find out. The district’s board of commissioners has thrown its support behind a proposal for a ballot referendum that would put a property tax increase for the preserves directly in the hands of voters.

"Demand Justice" sculpture in Grant Park. Artist Maxwell Emcays will talk about his inspiration and Juneteenth, June 19, 2021. (Courtesy of Chicago Park District)

Green spaces across the Chicago area will serve as the backdrop for a number of Juneteenth celebrations this weekend, from live music and dance to discussions about the new federal holiday.

Liam Durnan hikes in Cook County’s Spring Lake Nature Preserve. (Patty Wetli / WTTW News)

Liam Durnan has been on a yearlong caper, hiking all 350 miles of Cook County forest preserve trails. “When people picture the forest preserve nearest them, most people think of it being the picnic groves,” he said. “They don’t know how big this thing is. It’s just incredible.”

Legend has it that ramps, growing wild in forests, are the “stinky onion” that gave Chicago its name. (Moira Gibson / Pixabay)

It’s illegal to forage in Cook County forest preserves. Every year, 100 citations are issued for poaching, a significant number of which involve ramps, the wild leek that gave Chicago its name.

Vivid blue-green plumage and an unmistakable bright red bill are hallmarks of the male broad-billed hummingbird. (Courtesy of Nathan Goldberg)

Chicago birdwatchers were treated to a rare glimpse of a wayward hummingbird at LaBagh Wood, far beyond its normal range of the U.S.-Mexico border.