Featured subspecies: Ecuadorian Mantled Howler Monkey (Alouatta palliata aequatorialis)

Ecuadorian Mantled Howler Monkey (Alouatta palliata aequatorialis)

Ecuadorian Mantled Howler Monkey (Alouatta palliata aequatorialis) is the most studied monkey of Panama, but only for the area of the Panama Canal and Barro Colorado Island (BCI). It is a subspecies of the mantled howler monkey, A. palliata, and differs from the Golden-mantled Howler (A. p. palliata) primarily by being paler, with a more yellowish mantle. They eat fruit, leaves and flowers; including those of Ficus insipida, Spondias mombin and Cecropia insignis.

Ecuadorian Mantled Howler Monkey (Alouatta palliata aequatorialis)

The range limits separating A. p. aequatorialis from A. p. palliata are not clear. A.p. aequatorialis ranges from eastern Panama (or possibly the eastern tip of Costa Rica), including eastern Panama Canal basin, BCI, Chagres, Darién, and San Blas, reaching Colombia, Ecuador and northern Peru.  These photos were made in Pipeline Road, Gamboa, Panama Canal Area. This subspecies is listed as Vulnerable as it is estimated that it will experience a decline exceeding 30% over 3 generations (36 years) largely due to past and ongoing rates of habitat loss due to deforestation in northern Colombia, Ecuador, and south-western Panama, as well as from hunting. It was even used by the United States military forces and the Panama Defense Forces as an alternative source of protein in their jungle survival courses. Unfortunately, they have been partially extirpated from some unprotected areas of Panama.

Ecuadorian Mantled Howler Monkey (Alouatta palliata aequatorialis)

Botflies (Alouattamyia baeri syn. Cuterebra baeri) larvae develop in their skin, forming large abscesses. The larvae do not necessarily kill the monkeys, but may further weaken animals that are already suffering from malnutrition. These black flies are large, 1.8 to 2 cm (0.7-0.8”) in length, and the maggots reach 2.4 cm (0.95”) long and 1.5 cm (0.6”) wide. When flies that were collected from the howler populations on BCI were reproduced in captivity, it was found that female flies produced an average 1400 eggs each, laid in discrete rows. These eggs required the appropriate heat stimuli to hatch into parasitic larvae that then invade their host through the nose and mouth where it migrates to the neck and opens a larval pore. The larva reside in the howler’s neck for approximately 6 weeks, passing through 3 instars (developmental stages). After this, the larva drops out of the monkey and burrows into the soil where it finishes the last developmental (pupa) stage underground. The entire life cycle takes approximately 13 weeks. Interestingly, a 1998 publication states that in a study, none of the larvae infested in test rabbits survived to pupate.

Ecuadorian Mantled Howler Monkey (Alouatta palliata aequatorialis)

As if having large maggots in their necks wasn’t bad enough, the hole they made in the monkeys remains open for several days. Then screw-worm flies (Cochliomyia hominivorax) may lay eggs in these open flesh wounds. When these larvae hatch, they feast on anything surrounding that wound. Some monkey cadavers were even found with hands eaten down to the bone, and this infestation has a higher killing ratio than botflies.