User:UtherSRG/Fossa description

Description

The Fossa appears as a diminutive form of a large felid, such as a Cougar, but with a slender body and muscular limbs, and a tail nearly as long as the rest of the body. It has a mongoose-like head, relatively longer than that of a cat, although with a muzzle that is broad and short, and with large but rounded ears. It has medium brown eyes set relatively wide apart with pupils that contract to slits. Like many carnivorans that hunt at night, its eyes reflect light; the reflected light is orange in hue.

Both males and females have a short, straight pelage that is relatively dense and is without spots or patterns. Females are a reddish-brown dorsally and colored a dirty cream ventrally. Males are similarly colored, although some have an orange coloration to their abdomen from gland secretions when in rut, although some researchers have failed to observe this. Darker, blackish individuals are known, as are whitish ones, but there is no consensus as to whether these are melanistic and leucistic individuals, folklore, or simply general pattern distinctions. Locals call the reddish morph fosa mena, and the larger blackish morph fosa mainty. The tail tends to be lighter in coloration than the animal's sides. Juveniles are either gray or nearly white.

Its head-body length is 70–80 cm (28–31 in) and its tail is 65–70 cm (26–28 in) long. There is some sexual dimorphism, with adult males (weighing 6.2–8.6 kg (14–19 lb)) being larger than females (5.5–6.8 kg (12–15 lb)). Smaller individuals are typically found north and east on Madagascar, while larger ones to the south and west, likely due to Bergmann's rule. Unusually large individuals weighing up to 20 kg (44 lb) have been reported, but there is some doubt as to the reliability of the measurements.

Several of the animal's physical features are well adapted to climbing through trees. It uses its tail to aid in balance and has semi-retractable claws that it uses to climb trees in its search for prey. It has semiplantigrade feet, switching between a plantigrade-like gait (when arboreal) and a digitigrade-like one (when terrestrial). The soles of its paws are nearly bare and covered with strong pads. The Fossa has very flexible ankles that allow it to readily grasp tree trunks so as to climb up or down trees head first or to leap to another tree. Captive juveniles have been known to swing upside down by their hindfeet from knotted ropes.

Cranium (dorsal, ventral, and lateral views) and mandible (lateral and dorsal views)

Overall, the Fossa has features in common with three different carnivoran families, leading researchers to place it and other members of the Eupleridae alternatively in Herpestidae, Viverridae and Felidae. Felid features are primarily those associated with eating and digestion, including teeth shape and facial portions of the skull, the tongue, and the digestive tract, typical of its exclusively carnivorous diet. The remainder of the skull most closely resembles those of genus Viverra, while the general body structure is most similar to that of various members of Herpestinae. The permanent dentition is 3.1.3-4.13.1.3-4.1, with the deciduous formula being similar but lacking the fourth premolar and the molar. The Fossa has a large, prominent rhinarium similar to that of viverrids, but has comparatively larger, round ears, almost as large as those of a similarly sized felid. Its facial vibrissae are long, with the longest being longer that its head. Like some mongoose genera, particularly Galidia (which is now in the Fossa's own Eupleridae family) and Herpestes (of Herpestidae), it has carpal vibrassae as well. Its claws are retractile, but unlike those of Felidae species, they are not hidden in skin sheaths. It has three pairs of nipples (one inguinal, one ventral, and one pectoral) to support a litter of two to four young.

The Fossa has several scent glands, although the glands are less developed in females. Like herpestids it has a perianal skin gland inside an anal sac which surrounds the anus like a pocket. The pocket opens to the exterior with a horizontal slit below the tail. The genus name Cryptoprocta refers to this hidden (crypto-) anus (procta). A gland on its chest produces a reddish substance that stains the abdominal fur of males in rut. Other glands are located near the penis or vagina, with the penile glands emitting a strong odor. Like the herpestines, it has no prescrotal glands.

One of the more interesting physical features of this species is its external genitalia. Males have an unusually long penis and baculum, reaching to between its forelegs when erect. The glans extends down the shaft about halfway and is spiny except at the tip. In comparison, the glans of felids is short and spiny, while that of viverrids is smooth and long. The female Fossa exhibits transient masculization, starting at about 1-2 years of age, developing an enlarged, spiny clitoris that resembles a male's penis. The enlarged clitoris is supported by an os clitoridis, which decreases in size as the animal grows. Females do not have a pseudo-scrotum, but they do secrete an orange substance that colors their underparts, much like the secretions of males. Hormone levels (testosterone, androstenedione, dihydrotestosterone) do not seem to play a part in this transient masculization, as those levels are the same in masculinized juveniles and nonmasculinized adults. It is speculated that the transient masculization either reduces sexual harassment of juveniles females by adult males, or reduces aggression from territorial females. While several other mammal species (such as the Spotted Hyena and the Binturong) have a pseudo-penis, none of them are known to have theirs diminish in size as the animal grows.

• Comment to myself and readers: Hrm... HMW1 says the ears are short, while Kohncke says they are large. I suppose it's a matter of what other ears they are being compared to. And to my eyes, the ears in the pictures look large to me.

• The contradiction may come from interpretation. I've read that they have "rounded ears", which put together may mean that they have large but short, rounded ears... unlike maybe a lynx which has longer ears. – VisionHolder « talk » 01:09, 25 May 2010 (UTC)

• Ok, I think I have it consistent now. - UtherSRG (talk) 11:55, 26 May 2010 (UTC)

Mating and reproduction

Most of the details of reproduction in wild populations are from the western dry deciduous forests; whether certain of these details are applicable to eastern populations will require further field research. Mating typically occurs during September and October, although there are reports of it occurring as late as December, and can be highly conspicuous. Intromission usually occurs in trees on horizontal limbs about 20 m (66 ft) off the ground. Frequently the same tree is used year after year, with remarkable precision as to the date the season commences. Trees are often near a water source, and have limbs strong enough and wide enough to support the mating pair, about 20 cm (7.9 in) wide. Some mating has been reported on the ground as well.

As many as eight males will be at a mating site, staying in close vicinity to the receptive female. The female seems to choose the male she mates with, and the males compete for her attention of the female with a significant amount of vocalization and antagonistic interactions. The female may chose to mate with several of the males, and her choice of mate does not seem to have any correlation to the physical appearance of the males.

To stimulate the male to mount her, she gives a series of mewling vocalizations. The male mounts from behind, resting his body on her slightly off-center, a position requiring delicate balance; if the female were to stand, the male would have significant difficulty continuing. He places his paws on her shoulders or grasps her around the waist and often licks her neck. Mating is incessant and may last for nearly three hours. This lengthy mating is exceptionally interesting due to the physical nature of the male's erect penis, which has backwards-pointing spines along most of its length. Fossa mating includes a copulatory tie, which may be enforced by the male's spiny penis. The tie is difficult to break if the mating session is interrupted.

Copulation with a single male may be repeated several times, with a total mating time of up to fourteen hours, while the male may remain with the female for up to an hour after the mating. A single female may occupy the tree for up to a week, mating with multiple males over that time. Also, other females may take her place, mating with some of the same males as well as others.

The birthing of the litter of one to six (typically two to four) takes place in a concealed location, such as an underground den, a termite mound, a rock crevice, or in the hollow of a large tree (particularly those of the Commiphora genus). Contrary to older research, litters are of mixed sexes. Young are born in December or January, making the gestation period 90 days, with the late mating reports indicating a gestational period of about 6-7 weeks.

The newborns have nearly white fur, are blind and toothless, and weigh no more than 100 g (3.5 oz). After about 2-3 weeks the cubs eyes open, they become more active, and their fur darkens to a pearl grey. The cubs don't take solid food until 3 months of age, and don't leave the den until they are 4.5 months of age; they are weaned shortly after that. After the first year, the juveniles are independent of their mother. Permanent teeth appear at 18 to 20 months. Physical maturity is done by about 2 years of age, but sexual maturity doesn't happen for another year or two, and the young may stay with their mother until they are fully mature. Lifespan is up to or past 20 years of age, possibly due to the slow juvenile development.

Refs

Comments Sasata (talk) 14:49, 19 May 2010 (UTC)

1. maybe change venter to abdomen; pelage to fur?
2. how long is the fur (or does "fine" imply that it's short?)
3. if males weigh more, surely they are longer as well?
4. Could you review the article I found at http://smallcarnivoreconservation.org/sccwiki/images/b/bf/SCC37_Mueller_et_al.pdf and possibly include it in the breeding section?
5. more details: "solid food is not taken for 3 months"; "growth is complete at 2 years, although they are not sexually mature for another two years."; "The female mates with several of these, sometimes copulating incessantly over a long period (up to 165 minutes)... The prolonged mating period is all the more surprising when one considers the structure of the male genitalia. The penis is supported by a bone and covered with hard, backward-pointing spines. When erect, these spines stick out, and are probably responsible for the lock seen between mating fossas, similar to that between domestic dogs." That last factoid would make a prize-winning DYK.
6. "Fossas also undergo a strange development phase unknown in other mammals. During their adolescence, female fossas take on some distinctly masculine characteristics not seen in adult females. The clitoris grows disproportionately, develops a small supporting bone, and becomes covered with spines. In addition, the cream fur of the underparts is colored by a bright orange secretion. In adult fossas, this secretion is only seen in males. This temporary "masculinization" has not been identified in any other female mammals, and it remains unclear whether it is a mysterious adaptation or an unusual side-effect of pubescent hormonal changes."

• All quotes from "The Princeton Encyclopedia of Mammals" (2009), p.668-69. Sasata (talk) 17:43, 20 May 2010 (UTC)

  I believe these details are also covered in the Hawkins articles from the book The Natural History of Madagascar. I've cited the article on my sandbox, and if someone could distribute a digit copy to all the editors, I'd greatly appreciate it. (The book is too massive for me to scan it on my dinky scanner.) I cannot recommend that article strongly enough. It is very detailed about many aspects of the Fossa biology. – VisionHolder « talk » 19:45, 20 May 2010 (UTC)

If no one scans it before I'm back home at the start of June, I'll pick up my own copy. - UtherSRG (talk) 07:10, 21 May 2010 (UTC)

Responses UtherSRG (talk) 15:09, 19 May 2010 (UTC)

1. I like pelage as it's used often in our zoology articles and generally has a distinction from fur, but I can change venter.
2. Yes, short. I'll work on that. Although "fine" could also mean "thin" or "soft". I know "short" is correct, but so might other answers.
3. Not necessarily as they could simply have more muscle mass. The sources don't say.
4. Will do.... there's definitely some I can use.
5. Done
6. Done- this is not entirely unique to Fossas. Hyena females also have a pseudo-penis. the transitory nature is unique.