BROADKILL BEACH, Del. - A newborn bottlenose dolphin found dead along Broadkill Beach is believed to have been killed by other dolphins, according to Marine Education, Research & Rehabilitation Institute Executive Director Suzanne Thurman.
The dolphin calf, discovered on May 11, was the first newborn dolphin documented this season, Thurman said. Based on physical characteristics, the organization estimated the calf was likely less than 2 weeks old.
“It was still in the age class that we consider a neonate or a newborn, which is within the first 10 weeks of life,” Thurman said. “They have a really soft, floppy dorsal fin, and their teeth are barely erupted, and they have these striations on the side that are called fetal folds.”
Thurman said the animal’s injuries were consistent with “dolphin infanticide,” a phenomenon in which groups of dolphins repeatedly attack and ram a calf until it dies.
“There are theories about why it happens, but it’s not completely confirmed,” Thurman said. “One theory is that groups of male dolphins attack the calf because they want to mate with the mother, and she will not produce another dolphin while she’s still caring for the one she has.”
Thurman said a calf’s mother and another dolphin often attempt to protect newborns during these attacks but are typically unable to stop the larger groups of dolphins.
MERR said they usually document about six newborn dolphin strandings each season, though not all are linked to infanticide. Beachgoers played an important role in determining the cause of death, by quickly reporting the stranded calf. This allowed crews to examine it before decomposition and scavenging worsened.
Because the calf had already started decomposing, crews collected samples and data on the beach and do not plan further examination. The dolphin was buried in the sand.
Bottlenose dolphins are commonly seen along the Delaware coast this time of year as they follow fish populations through inland bays and nearshore waters.
In July 2025, a bottlenose mother and calf were found near the Milton town docks along the Broadkill River. MERR said at the time that the dolphins were likely chasing schools of fish.
