Whales, Dolphins, and Porpoises of the Western North Atlantic Part 17

Sperm whales (p. 57) have a squarish head that may somewhat resemble that of an adult male northern bottlenosed whale. However, there are numerous characteristics which will permit these species to be distinguished even from a distance:

NORTHERN BOTTLENOSED WHALE SPERM WHALE

BLOW

Low and bushy; projects Low and bushy, projects upward from indentation on obliquely forward from left top of head. side of head; usually less than 8 feet (2.4 m).

COLORATION

Lighter brown; adults splotched Brownish gray; body appears with grayish white; wrinkled.

body smooth.

FLUKES

Rarely notched; seldom raised Notched; raised on long dive.

on long dive.

HEAD

Tapering in younger animals; Squarish, long, all black; bulbous in adults; beakless.

white in older animals; beaked.

A further aid to distinguis.h.i.+ng northern bottlenosed and sperm whales at sea is the fact that the sperm whales that are found in areas where northern bottlenosed whales are encountered are usually older, larger males from 40 to 60 feet (12.2 to 18.3 m) long. Northern bottlenosed whales do not exceed 32 feet (9.8 m).

Northern bottlenosed whales may also be confused with the poorly known North Sea beaked whale (p. 82). When they can be examined at close range, however, northern bottlenosed whales should be distinguishable on the basis of the distinctly bulbous forehead.

Distribution

In the western North Atlantic, northern bottlenosed whales are restricted to Arctic and north temperate waters, where they most commonly occur in offsh.o.r.e areas. They have been reported from Davis Straits and the entrance to Hudson Strait, the Gully southeast of Sable Island, and as far south as Narragansett Bay, R.I.

In the spring and summer they concentrate near the northern limits of their range, occasionally visiting deep channels of the Gulf of St.

Lawrence and eastern Newfoundland in summer. During these seasons they may extend to the edge of the pack ice.

In the fall and winter the bulk of the population migrates southward.

Many probably winter in the Labrador Sea while others move farther southward and farther offsh.o.r.e.

Stranded Specimens

Like the beaked whales discussed on p. 70 through 83, the northern bottlenosed whales have no notch in the tail flukes, have two throat grooves forming a V-shape on the chin, and have only two teeth in the lower jaw, with those teeth emerged from the gums only in adult males.

These teeth may have sometimes fallen out of older males, but the tooth sockets should still be visible in the gums.

NOTE: Some specimens--both male and female--will be found to have a series of vestigial teeth the size of toothpicks in the upper and/or lower jaws. Similar vestigial teeth, 5-40 in number, sometimes occur in goosebeaked whales (p. 70). Further when they are prepared for museum collections, the lower jaws of adult northern bottlenosed whales may be found to contain a second pair of teeth just behind the first.

Northern bottlenosed whales may be distinguished from the remainder of the beaked whale family, however, by the extremely robust body, by the bulbous forehead, which is more extensively developed in larger animals, particularly males, and by the p.r.o.nounced dolphinlike beak.

[Ill.u.s.tration: Figure 67.--Northern bottlenosed whales at sea off Nova Scotia. Note the prominent dorsal fin and the blotches of grayish-white coloration on the body. Northern bottlenosed whales reach 32 feet (9.8 m) in overall length. (_Photo by H. E. Winn._)]

[Ill.u.s.tration: Figure 68.--Views of the heads of male northern bottlenosed whales off Nova Scotia. Note the distinctive beak (right) and the bulbous forehead, features which develop with age and are most p.r.o.nounced in adult males. In the animal on the left, note also the low bushy blow emanating from the indented area on the top of the head.

(_Photos by H. E. Winn._)]

[Ill.u.s.tration: Figure 69.--Northern bottlenosed whales occasionally raise their tail flukes when beginning a dive. At close range, these flukes can often be seen to lack a distinctive notch on the rear margin.

(_Photo from off Nova Scotia by J. Hain._)]

[Ill.u.s.tration: Figure 70.--A stranded northern bottlenosed whale from Holland. Note the bulbous forehead, the long dolphinlike beak and the frequent absences of a notch in the rear margin of the tail flukes.

(_Photo by J. P. Strijbos, courtesy of Rijksmuseum van Natuurlijke Historie te Leiden._)]

GOOSEBEAKED WHALE (T)

_Ziphius cavirostris_ G. Cuvier 1823

Other Common Names

Ziphius, Cuvier's beaked whale, grampus (St. Vincent) (see also p. 96).

Description

Goosebeaked whales reach a length of 23 feet (7 m). Females are slightly larger than males of the same age. Calves are probably less than about 6 feet (1.8 m) at birth. The head is small relative to the body length and, when viewed laterally, is slightly concaved or scooped on the upper margin. The cleft of the mouth is small, smaller than in any other species of beaked whales. The beak is indistinct in larger individuals.

There is a distinct indentation on the back behind the head. Two teeth are found at the tip of the lower jaw of adult males only.

The dorsal fin is relatively tall and distinct, to at least 15 inches (38.1 cm), smoothly falcate, and located well behind the midpoint of the back. The blowhole is located far forward on the top of the head. The blow, which may project slightly forward and slightly off to the left, is usually low and inconspicuous. Though the first blow after a long dive may be more distinct, even it is rarely visible even under good wind conditions for more than a few hundred yards.

Descriptions of the color pattern vary. Individuals may be dark rust brown, slate gray, or fawn colored on the back and generally lighter on the belly. Some appear dark in both regions, still others--particularly youngsters--appear lighter gray or tan on the belly. The body is frequently covered with white or cream-colored blotches (particularly on the belly). The tail flukes are dark on the bottom. The head is frequently paler in color. Old males have a distinct white head and are frequently extensively scarred.

Natural History Notes

Goosebeaked whales frequently occur in groups of from 10 to as many as 25 individuals. They have been reported to jump clear of the water. They are presumably deep divers and are known to stay down for more than 30 min. When they begin a deep dive, they often raise their tail flukes above the surface and dive nearly vertically. Goosebeaked whales feed primarily on squid.

May Be Confused With

So little is known of the external appearance and behavior of the living beaked whales at sea that all the species may easily be confused.

Goosebeaked whales are larger than all other beaked whale species with the exception of the northern bottlenosed whale. Upon close examination they may be distinguished from the northern bottlenosed whale by the lighter coloration of the head, reaching an extreme in the white head of adult males. (See p. 67 and Fig. 75.)

Distribution

As with other species of beaked whales seldom encountered or at least seldom positively identified at sea, the distribution of goosebeaked whales is poorly known and must be constructed from records of stranded specimens. Such records, often involving sick individuals that may have washed ash.o.r.e from considerable distances, may give an inaccurate picture of normal ranges.

In general, stranding reports suggest that goosebeaked whales are spa.r.s.ely but widely distributed in nonpolar lat.i.tudes. They appear to be primarily tropical in distribution, though they venture into temperate areas in summer. They have been reported from Ma.s.sachusetts and Rhode Island south to Florida and thence to the islands of the West Indies.

They are frequently stranded along the Florida coast and are not an uncommon species in the extant whale fishery of the Antillean Islands.