Products made from elephant ivory and skins are still being sold on Craigslist sites in the US, conservationist groups say, reviving longstanding concerns over the online market for illegal wildlife items. In a report published this week, the International Fund for Animal Welfare (IFAW) and Wildlife Conservation Society (WCS) flagged 522 posts selling elephant ivory and other wildlife products, including tusks, jewelry, and furniture. The posts, identified across 28 US cities between March 16th and 20th of this year, encompassed 615 items with a combined list value of nearly $1.5 million.

The elephant ivory trade remains a lucrative business for poachers, buoyed by high prices and strong demand. A 2014 report found that poachers killed nearly 100,000 African elephants in just three years, and experts say the trend has continued unabated, despite government pledges to crack down. The battle against poaching has largely focused on China, where ivory is seen as a status symbol for a rising middle class, but the groups behind this week's study say their findings point to a thriving market in the US, as well.

"We have an issue here in the US that needs to be dealt with."

"I think it sends a very powerful message that we have an issue here in the US that needs to be dealt with," says John Calvelli, WCS executive vice president for public affairs and director of the 96 Elephants campaign. "We should not be hypocritical and point the finger at others when we have issues here in the United States."

The US signed a global ban on ivory from Asian elephants in 1975, and from African elephants in 1990. Products that entered the country prior to these dates can be sold legally, but only 3 percent of the listings identified in this week's study included the necessary documentation. And although others claimed to include "pre-ban" or "antique" ivory, there is no way to determine their actual provenance. That doesn't necessarily imply that the other products included pre-ban ivory, and there's no data on how many were actually sold. But Calvelli says the prevalence of ivory products on the site underscores a need for stronger regulation.

IFAW and WCS notified Craigslist of their findings prior to publishing the report Tuesday, and the site responded by adding explicit mention of elephant ivory to its list of prohibited items. The groups welcomed the move as an encouraging first step, but called upon the site to implement more aggressive measures, such as search filtering tools that would automatically flag any ivory items. (Craigslist did not respond to requests for comment from The Verge.)

"We’re not asking anybody to do things that are impossible."

Part of the problem, experts say, is that ivory products from poached elephants are often altered to look aged and antique, making them even more difficult to police on online marketplaces. Google, eBay, and Amazon came under criticism from conservationist groups in 2013 over ads for elephant ivory products, many of which were listed under code terms like "white gold" and "unburnable bone."

"Despite well-intentioned policies to ensure compliance with the law, e-commerce (particularly platforms that connect private sellers to consumers) can be hard to regulate," Rachel Kramer, a wildlife trafficking expert at the World Wildlife Fund (WWF), said in an email, adding that stronger mechanisms are needed to verify that purportedly "antique" items did not actually come from poached elephants. But there are models for Craigslist to follow, as this week's report notes. eBay introduced search filters after a 2008 IFAW report unearthed more than 4,000 listings for ivory products on the site, and Etsy has implemented a broad ban on illegal animal products. IFAW followed up with a 2014 investigation which showed that eBay's measures have been effective.

"The technology is there," Calvelli says. "We’re not asking anybody to do things that are impossible."