A pilot whale, despite what the name suggests, is not a whale that flies! Neither is it really a whale, but rather a large dolphin in the family Delphinidae. The genus Globicephala is shared by only two species of odontocetes: the short-finned pilot whale (Globicephala macrorhynchus), and the long-finned pilot whale (G. melas).
The name “pilot whale” originated with an early theory that pods were “piloted” by a leader. Like killer whales, pilots form matriarchal societies, and it was long believed that group decisions were dictated by an older female leader. While recent evidence suggests more democratic decision making, the name stuck! Other common names include the “pothead whale” (named after the bulbous melon), and “blackfish” (a catch-all term used to designate numerous species of small, dark-coloured odontocetes like pilot whales, pygmy sperm whales and false killer whales).
Pilot whales are born light grey, but will progressively turn dark grey or black, with only some light areas such as a grey saddle patch behind the dorsal fin, a light grey or white anchor-shaped patch under the chin and belly, and a blaze marking behind the eye. They have stocky bodies, bulbous heads, flukes with sharply pointed tips, and the dorsal fin set forward on body. Adults males measure in at about 5.5 meters (18 ft) in length, whereas females only reach 3.7 meters (12 ft). Adults can weigh from 1,000 to 3,000 kg (2200-6600 lbs), but when they are born, short-finned pilot whales are only about 1.4–1.9 m (4 ft 7 in–6 ft 3 in) long and weigh 60 kg (130 lb).
Long-finned and short-finned pilot whales are often hard to tell apart in the field. One easy clue, as their names indicate, is that short-finned pilot whale flippers are shorter than those of the long-finned pilot whale (generally about 1/6th of the body length, compared to 1/5th for long-finned). Short-finned pilot whales also have fewer teeth – 7-9 in each row – and a shorter and broader rostrum. Both species exhibit sexual dimorphism and have similar lifespans of about 45 years for males and 60 years for females, with long-finned pilot whales being generally larger of the two.
Pilot whales can be found in oceans nearly worldwide, but the two species have limited overlap; long-finned pilot whales are found in cooler temperate waters, while the distribution of short-finned pilot whales is largely tropical and subtropical. Pilot whales are generally nomadic, but some populations stay year-round in places such as Hawaii and parts of California. Professional divers, pilot whales often frequent the deeper waters of the continental shelf break and slope.
Pilot whales are economically important in the whale-watching industry of some areas of the world, such as Madeira and the Canary Islands, both of which host resident populations of short-finned pilot whales. In the eastern North Atlantic, a population of long-finned pilot whales attracts tourists to the maritime provinces of Canada. The effects of tourism activities on pilot whales have not been well studied, but some evidence suggests that the impact of underwater noise from whale-watching boats can have the potential to significantly disrupt communication at close range. Increased boat traffic is also a concern, and some whales have been documented bearing scars that were likely caused by boat engines. Many countries now offer safe whale-watching guidelines designed to minimize the impact of their activities on the animals being watched, but the implementation of these rules is lacking in most places.
Short-finned pilot whales are long-live, slow to reproduce, and highly sociable animals. They are found in groups of 10 to 30 individuals, though pods of up to several hundred short-finned pilot whales have been reported. Pods are primarily matrilineal, or female-based societies, similar to those of resident killer whales. Pilot whales partake in many of the surface behaviours typically observed in dolphin speices, such as lobtailing (slapping their flukes on the water surface), spy-hopping (poking their heads above the surface), and even occasionally breaching. Members of a pod have also been observed making various kin-directed behaviors, such as babysitting calves that are not their own while other members of the pod feed.
Male pilot whales are polygynous, meaning they will mate with multiple females at one time and throughout their lives. During mating aggregations, when several pods come together for a short period of time, males will temporarily leave their pods to mate with females from other pods, but will return to their own pods once mating is over. This strategy helps to prevent inbreeding, wile still keeping whale families intact. Female pilot whales mature at about 7-12 years of age, and will start having calves every five to eight years, averaging about 4 to 5 calves in a lifetime. A calf will suckle its mother for a minimum of two years, with most continuing to suckle for five years, and some evidence suggest that females may continue to lactate for up to 15 years after the birth of their last calf! Pilot whales are also one of the few species of animals besides humans who experience reproductive senescence: female will usually stop reproducing once reaching the age of 40 years, even though the maximum lifespan exceeds 60 years. This phenomenon is puzzling from an evolutionary perspective, but theories suggest that these “helpful grandmothers” greatly increase the survival and reproductive success of their group overall by sharing cultural knowledge and helping to raise the young of the group.
Pilot whales have been nicknamed the ‘cheetahs of the deep’ for their high-speed pursuits of squid at depths of hundreds of meters. While squid forms the majority of a pilot whale’s diet, they will also consume certain species of fish and octopus. Pilot whales have been recorded to feed at a maximum depth of 1018m (3340 ft) for a length of 21 minutes, although average dives tend to be shallower (around 700m) and last around 15 minutes. When foraging, a pod may spread out up to cover an area 800 m (half-mile) wide to find food. Pilot whales have also been reported to “harass” sperm whales and chase dolphins, possibly as a way of competing for limited food sources.
Natural predators and strandings
There are no documented cases of natural predation on pilot whales, although the species could occasionally be targeted by killer whales or large sharks. Most of the data on pilot whale mortalities comes from mass stranding events; pilot whales are often involved in mass strandings throughout their range, with several locations in Australia, New Zealand, and the U.S having recurring incidents. Many theories have been proposed to explain these events, which include accidents in navigation that lead animals to unexpectedly shallow waters, anomalies in the earth’s geomagnetic fields impacting navigation, injury or disorientation caused by military sonar, or impaired navigation in diseased individuals that lead the rest of the group astray. Due to their tight social bonds, individuals will stay with their group, even when that means getting stranded. This also makes rescue attempts following strandings challenging, as whales will often re-strand themselves upon hearing the calls of their group members on shore. Stranding rescue is often difficult and dangerous work, and all individuals witnessing a stranding should contact local authorities to report the incident immediately.
Like many marine predators, pilot whales are susceptible to vessel strikes, entanglement and bycatch in pelagic fishing gear, such as gill nets, long lines and some trawl fisheries. Once entangled or hooked, whales may drag the gear behind them for long distances, resulting in fatigue, compromised feeding ability, or injury, often leading to reduced reproductive success and death.
Pilot whales have also been an important historical food source for many coastal communities around the world. Today, short-finned pilot whales are hunted in a few areas of Japan, mainly along the central Pacific coast, as well as the Lesser Antilles (e.g., St. Vincent and the Grenadines, St. Lucia, Dominica, Martinique), where whales are commercially hunted and the meat is available for human consumption. Long-finned pilot whales have traditionally been hunted in northern communities such as in the Faroe Islands, where whale hunting started at least in the 16th century, and continues into the modern day. Pilot whales’ strong social bonds and herding instincts make them prime candidates for so-called drive fisheries, where they are herded towards shore by boats and then killed in shallow waters. Other hunting methods include hand or crossbow-projected harpooning, and small-type whaling (defined as the use of a cannon mounted on a vessel below a certain size).
As top predators, pilot whales also suffer from the bioaccumulation of contaminants such as heavy metals and organichlorines in their tissues, which can may have serious long-term impacts on health and reproduction, and is a rising concern in cultures that consume pilot whale meat.
In the context of global warming, the ranges of short-finned pilot whales are expected to shift northward in response to warming temperatures, which could eventually lead to increased overlap and potential hybridization with their long-finned cousins. The distribution limit of short-finned pilot whales in the Northeast Atlantic has already shifted 3° latitude in only two decades, and evidence for hybridization is appearing in DNA samples from the Northeast Atlantic. Like many other species, pilot whales are also likely to be affected by changes in prey distribution and abundance, habitat degradation, and other secondary effects of climate change, coupled with human-mediated stressors such as marine traffic and pollution, which could lead to the global decline, or even loss of this species.
The North Sea and Baltic Sea populations of long-finned pilot whales are listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), as their status is unfavorable and could benefit significantly from international co-operation. Both species are covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS), the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS), the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU), and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU).
However, the IUCN lists both species of pilot whales as “Data Deficient” in the Red List of Threatened Species. Given the lack of population abundance estimates and trends over time, it is difficult to assess how the species as a whole are doing, and to identify areas where conservation efforts are most needed. Short-finned pilot whales are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), but unlike long-finned pilot whales they do not appear on either appendix of the Convention on Migratory Species. More research is needed to determine population trends and assess the impact of potential threats.
The Cape Breton Pilot Whale Project (CBPWP), founded in 1998 by members of the Whitehead Lab from Dalhousie University, is the world’s longest running study focused on this species! The research focuses on the social lives and vocalizations of long-finned pilot whales found off the northwestern coast of Cape Breton Island, Nova Scotia. I was fortunate enough to work for the CBPWP during my final year of undergraduate studies at Dal, and have forever fallen in love with these derpy but charismatic whales, and with the beautiful Cape Breton Island 💙