Environmentalists will ramp up their attempts to curb what they see as harmful population growth by distributing thousands of condoms adorned with pictures of polar bears, otters and other vulnerable creatures.

The US Census Bureau has projected there will be 322,762,018 people living in America on New Year’s Day – an increase of nearly 2.5 million over the past year. In 2016, it’s expected a baby will be born every eight seconds, with a death every 10 seconds in the US.

The Center for Biological Diversity said this spike in numbers is ample reason for green groups to shift human population growth back onto the agenda, after the issue became somewhat sidelined in recent years by climate change and other concerns.

The conservation group is leading the charge with its “endangered species condoms”. More than 40,000 of the free condoms have been distributed over the Christmas period, with the Center for Biological Diversity intending to escalate the campaign in 2016.

The condoms, which have been given out in smaller numbers since 2009, feature artwork of animals and slogans such as “Before it gets any hotter, think of the sea otter”, “Wrap with care, save the polar bear” and “For the sake of the horned lizard, slow down love wizard”.

The contraceptives have been handed out on student campuses, farmers’ markets and even to elderly people, who are encouraged to give them to their grandchildren.

“Grandparents remember when population was a big issue, so it’s fun for them to give them out to their grandchildren,” said Stephanie Feldstein, sustainability director at the Center for Biological Diversity.

“The condoms are very popular, they have been received very well. This time of year is the busiest time for getting busy so they are good stocking stuffers. It’s important that we give these out for free and to have volunteers talk about the impact of population [growth] upon wildlife and to increase access to reproductive healthcare.”

The center plans to distribute more than 100,000 free animal-themed condoms in 2016, to counter what it sees as unwarranted attacks on bodies such as Planned Parenthood and a lack of funding for programs to reduce unwanted pregnancies.

Feldstein said population growth is an environmental issue because burgeoning human numbers are “squeezing out” wildlife. Hotspots include southern California and Florida, where a ballooning population is resulting in habitat loss and increased vehicle-related deaths for species including the threatened Florida panther.

“We are gobbling up their habitat, not only directly with development but also through pollution from animal agriculture,” she said. “We are simply crowding out other species. This is a political problem because there needs to be more funding and more information. The number of states that require abstinence-only education is absurd.

“Population was a big part of the environmental movement a few decades ago and it fell off the radar. We think it’s important to get back in the agenda. Consumption is an important issue but so is the sheer number of people, there has never been a vertebrate species that has increased its population as quickly as humans, nor so destructively.”

Feldstein said she wasn’t concerned that a picture of a reclining otter may put amorous couples off their planned activities.

“We’d hope they would’ve got the conservation message before that point,” she said.