Flying snakes. Serpents that climb trees and launch themselves to the sky to chase their prey – these are an ophidiophobe’s nightmare. And while the name conjures a sizable mythical creature brimming with malice and ill will, the truth is that the snakes are smaller and far more innocuous. And they do not fly. They do, however, lurk around homes and more than a few alarmed gardeners in rural areas.
Flying snakes belong to the genus Chrysopelea, which has five species distributed from western India and Sri Lanka to much of Southeast Asia southwards to Indonesia. These arboreal snakes are distinguished by their flattened heads that are barely distinct from the neck and ventral scales that are keeled on both sides, a feature that is also seen in many other tree-dwelling snakes, such as the Asiatic bronzebacks (Dendrelaphis ssp.) and green ratsnakes (Gonyosoma ssp.).
The bronzebacks would be the snakes most similar in morphology to the flying snakes, but the mid-dorsal scales in the former are trapezoidal whereas it is the same as the rest in Chrysopelea. Dentition between the two are also very different; Chrysopelea are rear-fanged snakes, while bronzebacks are entirely nonvenomous. Nevertheless, in common with diurnal snakes that rely heavily on visual cues to search for prey and avoid potential predators, the eyes are large.
Compared to the two other related arboreal snakes Ahaetulla and Dryophiops, the pupils are round instead of being horizontal. The body is commonly in varying shades of green or brown, with a network of fine black patterning in the scales. In some species, such as C. paradisi, C. pelias, and C. rhodopleuron, the dorsum is decorated with a row of red spots edged anteriorly and posteriorly with black.
As stated above, the snakes have venom-conducting opisthoglyphic fangs situated from the rear of the upper maxillae, and though I am tempted to say that the venom is mild, the truth is that the venom is too weak to kill even their preferred prey items. Consuming prey is a straightforward process where the snakes swallow the prey alive or, if a bit too big, constriction is employed though the prey is swallowed alive just the same.
One species is found in the Philippines, the variable paradise flying snake (C. paradisi subsp. variabilis), a subspecies endemic to the archipelago. Despite the “paradise” connotation, the species name “paradisi” actually was derived from the Greek word “paradeisos,” which refers to a park; the holotype (the first, scientifically collected specimen deposited in a museum’s zoological collection) of C. paradisi was collected in Java, likely on a park, hence the name given.
Ecology and distribution
Paradise flying snakes are generalists, and occur either in more forested areas or within human habitation, such as towns, gardens, and coconut plantations. Apart from areas with vegetations, paradise flying snakes are also found in and on thatched roofs, wood piles, and among rocks on the ground. In this respect, the snakes have much in common with the bronzebacks (Dendrelaphis ssp.) than with the related long-nosed vine snakes (Ahaetulla ssp.) and the Asian arboreal whipsnakes (Dryophiops ssp.) both of which prefer some degree of original vegetation to feel more secure.
Not surprisingly, Chrysopelea lives sympatrically with bronzebacks and there might be a certain degree of competition where the two genera overlap, since the prey spectrum of both are nearly identical; Dendrelaphis also feed on frogs, though lizards make up the bulk of their diet.
Subspecies variabilis is endemic to the Philippines where they are found in virtually all the islands in the archipelago. These Philippine snakes are smaller than the nominate paradisi subsp. paradisi, attaining total lengths of about a meter (versus 1.4 meters for females). Males are shorter and slighter in build, and more brilliantly colored.
Anyone who has had ample experience or observations with these snakes can easily distinguish the sex of these snakes even in photos alone if the snakes illustrated are mature enough. Females are thicker and drabber in coloration, typically with very narrow black edging on the scales. Females also have less conspicuous red dorsal spots, and may lack it altogether.
Juveniles are black with narrow white cross bands; the white cross bands are red atop. The head is also black with thin white cross stripes but without the red coloration. Juveniles appear more terrestrial and the coloration may be a form of mimicry with coral snakes or kraits to deter possible predators.
Paradise flying snakes, including the Philippine subspecies, are notably arboreal snakes although there is a very wide gradient pertaining to their preferred distance from the ground. While there are individuals found in the canopies of tall trees, there are also those that can be encountered very close to the ground.
Indeed, some specimens have been observed either resting or foraging even in gardens, leading to startled gardeners. If sufficiently alarmed, the snakes attempt to flee in a shooting manner. When grabbed, the snakes deliver a series of staccato bites, though with the teeth being rather small, the damage incurred is no more than negligible pinpricks.
Not venomous enough
The defensive behavior is in stark contrast to that employed by the Asian long-nosed vine snakes (Ahaetulla ssp.) and bronzebacks (Dendrelaphis ssp.). Whereas Chrysopelea prefers striking in rapid succession, the two snakes mentioned above would rather plant their jaws firmly on their offender and chew their teeth, effecting trifling envenomation. It would seem that Chrysopelea themselves are aware of how weak their venoms are to be of any effect to their perceived aggressors.
Gliding or flying?
As their common name suggests, the snakes are primarily noted for their “flying” abilities. When chasing down prey or escaping would-be predators, the snakes hang to the tips of branches and hurl themselves into the air, flattening their bodies by spreading their ribs and creating a concave space in their center as they “swim” in the air and land a good distance away, the expanse covered aided by the snake’s head moving from side to side and effecting a swimming motion.
Among the species, C. paradisi is the one documented to possess the longest “lights.” However, since the snakes’ aerial maneuvers are still influenced by gravity instead of being independent from it, the “flying” designation is much more accurately interpreted as “gliding.”
Nevertheless, there is still some debate as to whether the concavity of the abdomen does indeed produce a parachute effect since due to the snakes’ narrow profile, there is little surface area to actually make the theory plausible. In the parachute effect, the air trapped beneath the space slows the descent and enables the snakes to stay aloft for a longer period of time than if they do not have the concave abdomens.
Still, it is likely that the resulting concavity during glides is just an artifact of the ribs spreading sideways, in which case aerodynamics is more at work than the aforementioned parachute effect. Critics of the supposed parachute effect in these snakes have also pointed out that animals distended with food or gravid females would not be able to employ the gliding behavior to escape would-be predators if ventral concavity during “flights” are of particular importanc.
Snakes from the genus Chrysopelea are the only serpents known to glide. Apart from the obvious advantages when hunting down prey or escaping natural enemies, gliding also provides an easier and more economical way to move from one spot to another instead of descending to the ground and climb up all over again.
Chrysopelea paradisi and its subspecies are predators and arboreal lizards, and literature suggests that geckos figure prominently in their diet. This might come as a surprise, considering that geckos are nocturnal animals and flying snakes are strictly diurnal, but my observations in captivity revealed that geckos resting during the day are easily spotted by the snakes if they make even brief movements, such as when flicking stray ants or moving towards the shade when sunlight reaches their perch.
The snakes’ large eyes are especially effective in spotting even obscurely colored lizards. The largest snakes even tackle more formidable gecko species, such as the highly defensive tokay gecko (Gekko gecko), and here, the snakes resort to constriction than resting their full faith in the quieting effect of their venom, which is weak. Only tokays of sufficiently smaller sizes are attacked.
Apart from geckos, agamids and arboreal skinks, such as Dasia and Lamprolepis, are on the menu, although the more mature individuals of the larger agamid species, such as those from the genera Bronchocoela and Gonocephalus, are avoided. The flying dragons (Draco ssp.), however, are fair game.
Juvenile C. paradisi are still arboreal but stay closer to the ground, often on shrubs or on rock walls. Despite a seeming absence of definitive observations, these small snakes most likely prey on the smaller and more slender skinks from the genera Emoia and Lipinia. American and European herpetoculturists have attempted to switch these snakes to a rodent diet, but the results are far from encouraging. Of the five Chrysopelea species, only C. ornata has proven to be the one most likely to accept a diet of mice.
Flying snakes, despite the horrific images they may conjure to the uninitiated, are a wonder of adaptation and evolution. Their presence around homes and gardens should be better interpreted as a vestige of vanishing natural world where they still feel secure of one driven by human fear and antipathy.
I certainly fell honored to see these snakes safe and secure in my own garden sanctuary.
This appeared in Animal Scene magazine’s March 2020 issue