CHICAGO — Chicago animal control officials have closed the eastern half of Humboldt Park and hired an expert from Florida as the search for an alligator in the park lagoon enters its second week.

The closure, which includes streets near the park, was done on the advice of the expert, Frank Robb, and is aimed at making the area around the lagoon as quiet and free from distractions as possible, according to Chicago Animal Care and Control.

“It is likely that residents who have been watching from the lagoon banks and paths in the park have been influencing the animal’s behavior,” Kelley Gandurski, executive director of CACC, said in a statement. “We are taking these steps in an attempt to create an environment that lends to the animal’s safe capture so we can quickly reopen the entire park to activity.”

The western half of Humboldt Park, which includes a swimming area and field house that hosts about 300 kids for day camp, remains open.

Closed are the boathouse parking lot, pedestrian pathways within the park and those bounded by Humboldt Park Drive, Division Street, California Avenue and North Avenue, and access to North Luis Munoz Marin Drive east of North Humboldt Drive. Parents can still drop children at the field house but will need to enter and leave the park from North Avenue.

Robb, who owns Crocodilian Specialist Services in St. Augustine, Fla., arrived in Chicago on Sunday and “immediately began assessing the park and lagoon,” according to the statement.

Authorities were called to the lagoon about noon Tuesday, hours after photos of the gator flooded social media.

The reptile, believed to be a 4- to 5-foot-long American Alligator indigenous to southern states, has drawn nationwide attention. “Alligator Bob,” a volunteer with the Chicago Herpetological Society, initially led efforts to capture the alligator.