But he cautioned that "knowing a cause doesn't always mean we can do something about it."
"We look at one animal at a time," Habecker said, dissecting each to extract tissues and organs, including the heart, lungs, liver, kidneys, stomach, and brain, to determine the cause of death. "It's not pretty, but that's how it's done."
Bob Schoelkopf, director of the Marine Mammal Stranding Center in Brigantine, N.J., that is shipping carcasses to Penn for necropsy, said results thus far show four cases of pneumonia and one of morbillivirus, a measles-like virus blamed for killing 742 bottlenose in the 1980s.
A brain worm infection - which is harder to detect - can also be a culprit, Habecker said.
Two dead dolphins were found Friday in Avalon and another in Lower Township, according to Schoelkopf.
Another died Thursday in Ocean City after washing up in the surf, alive but struggling. A sand tiger shark followed it in and took a bite out of it, he said: "We were very lucky there was a thunderstorm just before that cleared the beaches."
Necropsies on multiple dolphins might reveal a pattern, Habecker said, but it is not his hospital's role to determine whether there is an "epizootic event," or epidemic, in the Mid-Atlantic dolphin population.
That determination, he said, would fall to state environmental officials and the stranding center, a federally designated entity for retrieving dead or stranded marine mammals.
Habecker said "human interaction" - such as aggressive commercial fishing, toxic wastes, and even plastic bags - can contribute to spikes of mortality in marine mammal populations such as whales, seals, and dolphins.
"We find a lot of strange stuff," Habecker said, but some animals "never get a definitive diagnosis" of cause of death. And when there are multiple causes of death in a population, he said, "it's hard to know what's clinically relevant."
Rich Mallon-Day, executive director of the Outer Banks Center for Dolphin Research in Cape Hatteras, N.C., said studies in Tampa Bay have shown that morbillivirus outbreaks evidently occur every 20 to 25 years in that area.
County and local officials in New Jersey report no decline in tourism as a result of the scattered deaths but were hopeful that the situation would pass soon.
"It's a fragile tourist economy," said Scott Wahl, public information director for Avalon, where a bottlenose dolphin was discovered on the Fifth Street jetty Friday morning.
Wahl said tests show that the water at the beaches is clean. The water is tested three times a week.
Diane Weiland, spokeswoman for Cape May County, also cited reports that the water was testing clear.
"While we feel badly about what's happening, we're relieved the problem is not confined to South Jersey," she said.
Jim Cicchitti, owner of the Starlight Dolphin and Whale Watching Center in Cape May, said that bottlenose dolphins are abundant all along the South Jersey shore, but that his deep-sea fishing boat captains also spot them 70 miles offshore.
Chris Kanya, a Starlight dolphin-cruise captain, said that they tend to feed in shallower water, "where the bait is," and that between April and October there is rarely a day when tour boats fail to spot them.
Kanya said he had seen no signs of "illness or distress" among the local dolphins this summer. Like other captains, he said, he frequently sees the same animals off the shores of Wildwood Crest and Cape May, identifying them by their distinctive colorings and markings.
"Today we spotted eight or 10 just coming out of the channel" at Cape May, he said, "and about 200 off Cape May Point."
Contact David O'Reilly at 856-779-3841 or firstname.lastname@example.org, or @doreillyinq on Twitter.