The Sagalla caecilian lives underground, burrowing through the soil using its strong, bony head to compact soil and produce a burrow. They move through the soil by body undulation, and search for their prey, possibly by collecting chemical and tactile signals. In addition to their sense of smell through their nose, retractable tentacle sensors either side of their head near to their nostrils may also function to transmit chemical messages from the environment to the nasal cavity, which aids the caecilian in finding prey. The feeding mechanism of the Sagalla caecilian’s close relative (the Taita Hill’s caecilian) has been closely studied. They were found to employ rotational feeding, which is where the caecilian grabs a prey item and then rotates about the long axis of their body. This is a common behaviour in gape-limited creatures, and would seem to serve a dual purpose in caecilians. First, it may aid the breaking up of oversized food items. However, it is thought that caecilian prey is not always oversized so a second function of rotation may instead help them to judge prey size through the detection of how much spin force is required to move the object. Caecilians spend their time in narrow, dark tunnels, so rotational feeding allows the caecilian to gauge more information about its surroundings and prey.
The observation of caecilian behaviour is rendered difficult by their subterranean lifestyles. Many caecilian species are dietary generalists, feeding on earthworms and various species of other soil-dwelling invertebrate. Boulenger’s caecilians also feed on a range of prey items, most commonly termites and earthworms. Caecilians catch their prey using a variety of methods, which range from a “sit and wait” or stealth strategy, whereby they slowly approach the prey and then quickly seize it using a strong grab of the jaws, to active hunting of prey items using an acute sense of smell. Their main predators are probably snakes and birds, although they are thought to possess some defense mechanisms against predation. Their skin contains mucus and poison glands (as found in other amphibians), and caecilians are probably quite toxic to many potential attackers. They are often well camouflaged and spend the vast majority of their time underground away from a wide variety of potential predators. The principal predators of the Sagalla caecilian are thought to be driver ants (which are sometimes known as “killer” ants). Living in colonies of up to 20 million individuals, driver ants are a formidable force and may tackle prey up to the size of a zebra, although the bulk of their diet consists of earth worms. Since the Sagalla caecilian occupies a similar habitat to the earth worms, they too are hunted in their burrows.
All caecilians are thought to have internal fertilisation, in that the eggs are fertilised by the male’s sperm inside the female and not when they are being laid. Virtually nothing is known of caecilian mate recognition or courtship, although some aquatic species have been observed performing an undulating dance before mating. During mating, the male everts and inserts his phallus into the cloaca (or reproductive opening) of the female for up to several hours. The Sagalla caecilian is egg-laying (or “oviparous”), and in caecilians this means that the female lays her eggs in an underground chamber and then guards them until they hatch. This species is presumed to resemble its close relatives in having direct development, so the young hatch out from the eggs without first passing through a free-living larval stage. Caecilians can produce clutches of two to more than 100 eggs, and a Sagalla caecilian female has previously been found bearing five eggs.
It had been thought that following the hatching of the eggs in oviparous species, caecilian mothers provided little or no further care of their offspring. However, the Sagalla caecilian’s closest relative, the Taita African caecilian (Boulengerula taitanus), has recently been shown to exhibit the extraordinary behaviour of “maternal dermatotrophy” or skin feeding its young. The hatchlings possess special teeth that allow them to peel and eat their mother's skin, which contains a high level of fat and other nutrients. Indicated by the presence of special teeth in the hatchlings of other oviparous caecilians, skin feeding may have evolved in caecilians around 150 million years ago in the late Jurassic period. The young of the Taita African caecilian are therefore provisioned with both yolk whilst in the egg and, subsequently, a diet of the nutrient-rich skin of their mother when they hatch. This remarkable level of parental care has not yet been observed in the Sagalla caecilian. The specialised teeth have not been found in their independent young, but it is unclear whether this is because they had already been shed and replaced with the adult-like dentition in the observed stages or whether they do not skin-feed. More studies are needed to fully discover the life history of the Sagalla caecilian, although skin-feeding is expected to occur in the Sagalla caecilian based on its presence in its sister species and the possibly broader distribution of this trait among the closer relatives of Boulenger’s caecilians.
Sagalla caecilians possess a single developed lung (the left lung being considerably reduced or missing as is often the case in snakes) and they are also capable of gaseous exchange (or respiration) through their skin and the lining of their mouth. Local farmers on Sagalla Hill have reported that the Sagalla caecilian is more commonly encountered during the wet seasons, which is also known to be the case for the Taita African caecilian. The rains may encourage the Sagalla caecilian to move up into the upper layers of the soil where it becomes more visible to the farmers that cultivate the land. The Sagalla caecilian requires moist soil, both to maintain their moist skin and to provide a suitable habitat for their prey
This species is thought to have originally been present in montane forest soils, as well as that covered by bushy shrub vegetation, but this habitat has now been transformed into shambas (Kenyan smallholder farms). Most of the Sagalla caecilians observed by scientists so far have been unearthed from soil underneath banana plants or beneath decomposing organic debris within these farms, especially near to streams. The Sagalla caecilian therefore seems to be tolerant of small-scale farming activities. However, the density of animals is much higher near streams than in shambas away from streams, so the area of potentially preferred habitat within the possible range of the Sagalla caecilian is very small. Although Boulenger’s caecilians require moist soils, their reproductive mode (direct development of terrestrial eggs) has liberated them from a dependence on streams or other water bodies for their reproduction. The species has not been found in the Eucalyptus plantations that cover much of the Sagalla Hill area (due to soil desiccation, toxic accumulations of Eucalyptus leaf litter, and resultant limited prey), and is only found in very low abundance in the small remaining area of natural forest on the ridge of Sagalla Hill. This is potentially because this remnant forest is at a higher elevation than that apparently favoured by the species, or it could be due to the absence of suitable soil conditions or streamside habitat.
Currently very little is known about what constitutes suitable or optimal habitat for caecilians. For example, specimens of the Taita African caecilian observed in shambas have been found to be significantly smaller but more abundant than those inhabiting naturally forested areas of the Taita Hills. It is therefore difficult to determine whether the human alteration of the Sagalla caecilian’s habitat is having a long-term effect upon this species.
No population data are currently available for this species. However, within its extremely restricted range of about 29 km², the Sagalla caecilian is considered to be common in a small number of suitable habitats.
No population data are currently available for the Sagalla caecilian, but the population trend is assumed to be in decline by the IUCN Red List of Threatened Species.
The Sagalla caecilian is listed as Critically Endangered in the IUCN Red List of Threatened Species because it has an extent of occurrence of less than 100 km², is restricted to one location, and its habitat is undergoing a continuing decline in quality.
Sagalla Hill has been significantly deforested and only a small amount of natural forest remains within the range of the Sagalla caecilian. However, it is not clear whether these caecilians might sometimes benefit from human modified or disturbed habitat. The Sagalla caecilian appears to be tolerant of small-scale farming activities such as those practiced in the shambas on Sagalla Hill. The continued expansion of these farming activities has in recent years resulted in the removal of streamside vegetation causing severe flooding and an increase in the erosion of river banks. The substantial loss of earth washed away in these floods has removed soil where the Sagalla caecilian is known to breed and occur at its highest densities.
The main threats to the Sagalla caecilian would appear to be linked to the removal of native vegetation, with a number of negative consequences for this species. Clearance of native vegetation has increasingly led to the cultivation of steep slopes and the resultant erosion of good, thick soils for the Sagalla caecilian. Vegetation removal has also caused the drying out of soils in many areas of this species’ range, rendering the soil uninhabitable for the Sagalla caecilian because they probably require moist conditions. Shambas now extend all the way up to the streams in the area, which is drying out some of the best places for this species as they thrive in moist streamside soils. The conspicuous lack of Sagalla caecilians in the Eucalyptus plantations may also indicate that the species is unable to survive around this non-indigenous tree species. Eucalyptus trees probably affect the Sagalla caecilian in two main ways. Firstly these trees desiccate their surrounding, leading to compaction of the soil. Secondly, the presence of Eucalyptus trees has led to a thick accumulation of toxic leaf litter which decomposes very slowly and does not allow for the build up of communities of local insects and other soil invertebrates. This means not only is the soil rendered too dry and hard for Sagalla caecilians, but there are also no prey items.
Eucalyptus plantations have been present on Sagalla Hill for many years and many belong to the Kenyan government, making their removal very difficult. Continued presence (and any expansion) of the Sagalla Hill Eucalyptus plantations will negatively impact remaining populations of the Sagalla caecilian. Chemicals used in farming on Sagalla Hill, as well as other pollutants, may also pose a threat to this species.
The Sagalla caecilian is not known from any protected areas, although there are some limited conservation initiatives occurring for this species. An important first step was to raise the profile of this species among the local people of Sagalla Hill. A competition was organised for people in the small Sagalla community to find a new name for the Sagalla caecilian in the local dialect, kisagalla. On Sagalla Hill, the local name of the caecilian has always been “ming’ori” or earthworm. Providing this species with its own identity is a critical component of raising awareness about its plight. Patrick Malonza of the National Museums of Kenya (co-describer of this species and one of the organisers of the competition) explained the importance of naming the species locally: “If the animal has a local kisagalla name, we think that Sagalla people may recognise it for the special endemic species that it is. They have something unique to be proud of.”
Conservation International (CI), through its Critical Ecosystems Partnership Fund (CEPF), supports conservation projects in the region of Sagalla Hill. The Taita Hills (including Sagalla, Dawida, Kasigau and Mbololo) are part of the Eastern Arc Mountains and coastal forests (in Kenya and Tanzania) hotspot of biodiversity, and are therefore a conservation focus of CI. Many of the unique species in this region are threatened by habitat loss and degradation. Funding from CEPF is being used to understand the amphibian biodiversity of the region, as well as looking for sustainable ways of conserving the environment for people, animals and plants. Local and international scientists are currently measuring and monitoring all of the amphibian species in the area in the remaining naturally indigenous forests, exotic plantations and shambas. Working thorough local counterparts, this project aims to train local field assistants with a view to developing a sustainable long-term monitoring program.
However, much more can still be done to specifically conserve the Sagalla caecilian and its habitat.
It is an urgent priority to restore the vegetation along stream banks and on steep slopes within this species’ range in order to minimise erosion and loss of important soil habitat for the Sagalla caecilian.
The Sagalla caecilian is a very recently discovered species, and so little is currently known of its habits, habitat requirements and population dynamics. Further study of the ecology of this species would benefit future conservation panning as it may help inform decisions about habitat management and protection. This should involve the training of local conservationists, which could be achieved by appointing a local EDGE Fellow for the Sagalla caecilian.
Plans to remove the Eucalyptus plantations in the area would also be very beneficial for the species, as well as other native biodiversity. If the Eucalyptus plantations are removed, it is imperative that these areas are replanted with preferably native vegetation to stabilise the soil and prevent further erosion and desiccation. However, since this species has often been found associated with banana plantations, it is possible that the ecologically sensitive cultivation of bananas may also benefit this species, whilst providing an income for local communities. Because many of the Eucalyptus plantations on Sagalla Hill are government owned, their removal may require appealing to a policy-level decision making process. However, Eucalyptus trees were also planted on locally owned land, within the shambas. An initiative that provides subsidies for the removal of these locally-owned trees would be a positive step for the conservation of the Sagalla caecilian. Furthermore, encouraging ecologically sensitive arboriculture using native species (i.e. creating mixed species tree plantations that may also provide income for local people) and creating a special nature reserve within good habitat for the Sagalla caecilian would also be enormously beneficial for the survival of this species.
Project Manager for the Sagalla Caecilian conservation project