(CNN) -- The images of seals being harassed on a California beach are perplexing and disturbing.
In the middle of the night, two women sit on harbor seals, kick them or pull their flippers, all the while snapping flash pictures. The animals eventually flee into the water.
A newly installed video camera captures that attack and others on the seals, who have been using the beach at Children's Pool in La Jolla for decades.
Sara Wan of the Western Alliance for Nature said her organization installed the camera after years of people who are opposed to the seals' presence on the beach being cruel to the animals, trying to scare them off the sand.
"One of the things we found with the camera is it shows what we knew was going on before," she says. "Now people are seeing what is going on and saying, 'You're right, that's wrong.'"
San Diego Mayor Bob Filner placed a sunset to sunrise curfew on the beach, saying people can disagree about how a beach should be used, but they cannot abuse animals, CNN affilate KGTV reported. The restrictions end May 15 after pupping season is over.
The beach was a popular spot for parents to take their children for a safe place to swim, but harbor seals took over the beach in the early 1990s, KGTV said. Beach-access advocates want the area returned to its original use, the station reported.
Because most cases of animal abuse or neglect are never reported, it is difficult to say whether the number of incidents are increasing.
But with enhanced technology and social media, some of the most egregious cases have recently caught the attention of the media.
There were cases where people apparently were ignorant of the law, such as the woman in Florida who rode a manatee, and other more serious ones where people showed wanton disregard for wildlife, as in the case of two sea birds found struggling to breathe after someone forced beer cans over their heads.
In December, at least 10 dead dolphins washed up on beaches in the Gulf Coast. Some were shot, while others were stabbed.
It makes you wonder, what is wrong with people?
"I really don't understand how someone can be deliberately cruel to an animal like that. It's really baffling," says Sharon Young, marine issues field director with the Humane Society of the United States. "They know it's illegal, they know it's wrong."
Studies have shown that people who have little or no empathy for animals often have none for other humans, activists say.
Animal cruelty is a crime that mostly goes unreported. A 1997 report from the Massachusetts Society for the Prevention of Cruelty to Animals says that only 40% of people who witness abuse ever report it.
The same study found people who committed violent crimes against animals were five times more likely to commit violent crimes against humans than were other people who lived in the same neighborhoods.
According to the American Society for the Prevention of Cruelty to Animals, there are three reasons people abuse animals.
Most people, the ASPCA says on its website devoted to children, "don't think about or realize what they are doing." Take, for instance, the pet owner who doesn't understand how cruel it is to tie a pet up all day on a chain that is too short.
Another type of abuser is the person who is bowing to peer pressure. In those cases, the person, usually someone young, doesn't hurt or harass animals but a few times. Eventually, they learn to feel for the animal, the organization says.
The third category is people who enjoy hurting animals. These people are often looking to demonstrate their power, the ASPCA says.
Sometimes, people feel they are at odds with the wildlife, Young says.
It's a clash, where a growing human population wants the same space as the animal population, Wan says. The pressure is growing.
"And more and more we are taking it out on wildlife," she says.
Both Wan and Young agree that there isn't a problem with the legal penalties for animal cruelty, but with catching and convicting the bad guys.
"We don't need stronger laws, but clearly there is a need for stronger enforcement," Young says. "We need to make proverbial examples of some people."
Her organization works with groups to educate the public. In the case of the seals, the cruelty has "accelerated so rapidly" that activists are scrambling to do something, she said. They hope to create a video that draws attention to the problem.
For now, she and Wan hope the beach closure will help give the seals a respite from the types of incidents caught on camera.