Boulder animal control officers have opened an investigation into reports that two rock-throwing young boys injured a pair of ducklings that continue to recover at the Greenwood Wildlife Rehabilitation Center near Longmont.

The ducklings were brought in Thursday after William Nash said two kids - he thought they were 12 to 13 years old - struck them with rocks near 28th Street and Baseline Road in Boulder, separating them from their family.

Nash said the two boys throwing the rocks ran away from the scene. He added that there were a pile of rocks, and that the boys looked like they had been throwing them at the ducks for quite some time.

Boulder police spokeswoman Kim Kobel said Tuesday that an investigation has been opened, but that there was no new information or leads at this time.

The two mallard ducklings - who are about a week old now - were diagnosed by a veterinarian Monday with severe head trauma.

Jenny Bryant, the volunteer and outreach manager with Greenwood Wildlife, said the ducklings are showing some improvement.

"The good news is they continue to eat and they are both gaining weight," Bryant said. "It's sort of a waiting game. They'll be assessed every week, and if they continue to improve, we will treat them and give them all the help they need to grow up and hopefully be released back into the wild."

But Bryant said there is a concern that the ducklings could have suffered permanent vision impairments as a result of their injuries. Bryant said that, unfortunately, if the ducklings cannot survive on their own in the wild, they will have to be euthanized.

"Obviously that's not what we want to happen, so we will do everything we can to help them," Bryant said. "It's a very delicate situation."

Contact Camera Staff Writer Mitchell Byars at 303-473-1329, byarsm@dailycamera.com or twitter.com/mitchellbyars.