It was an adorable, furry surprise.

And it forced a PSE&G-contracted tree-trimming crew working in Morris County during mid-May had to immediately halt their work.

The crew had stumbled upon a den of three bobcat kittens in a thicket, according to Gretchen Fowles, a biologist for the New Jersey Division of Fish and Wildlife. Fowles said that finding bobcat kittens is "extremely rare."

The Nelson Tree Service crew, which had been contracted to clear a transmission right-of-way according to PSE&G, immediately stopped what they were doing and reached out to EcolSciences, Inc., an environmental monitoring company, for guidance. EcolSciences notified the state Division of Fish and Wildlife, which sent Fowles to check out the discovery.

"We just never know what our crews or contractors might find along our rights of way," said PSE&G Vegetation Manager Richard Arnold.

The kittens were identified as bobcats rather than feral domestics, and the crew decided to take their work elsewhere to not disturb the endangered kittens or their mother, who was likely lurking nearby. Fowles said that the kittens barely had their eyes open, and they were likely just a few days old.

A few days after the discovery, Fowles returned to the discovery site and found the kittens gone. Wildlife cameras were installed in the area by NJDFW, but there have been no signs of bobcats in the area since the discovery.

Unexpected Find! A den containing three kittens was recently found during routine vegetation maintenance by Nelson Tree... Posted by NJ Division of Fish and Wildlife on Monday, June 25, 2018

Bobcats are listed as endangered in New Jersey, though they are not listed on the federal level. Today, it is estimated that between 200 and 400 bobcats live in New Jersey. The cat's range once stretched across the entirety of the Garden State; today bobcats are only found in the northern counties.

By the 1970s, bobcats were considered extirpated from New Jersey. The state wanted to bring the bobcats back to help restore the natural ecosystem, and so 24 bobcats were caught in Maine and released in New Jersey between 1978 to 1982.

Fowles said that the May discovery of the three bobcat kittens is a good sign for the local population, because it shows active breeding among New Jersey bobcats. The cats breed between February and June, and females are pregnant for about 60 days before giving birth to a litter of 1-6 kittens.

In New Jersey, adult bobcats can weigh between 18 and 35 pounds depending on the gender and are about two feet tall. The cats typically prey on rabbits, mice, squirrels, ground-nesting birds and turkeys. They will also sometimes hunt deer.

Bobcats are shy animals that are rarely encountered by people, according to the NJDFW.

But as the bobcat population slowly recovers, interaction with humans will likely increase. The number of bobcats hit by cars is on the rise according to NJDFW; in 2017 there were eleven bobcats confirmed killed by vehicles on New Jersey's roads.

Michael Sol Warren may be reached at mwarren@njadvancemedia.com. Follow him on Twitter @MSolDub. Find NJ.com on Facebook.