Western Long-Beaked Echidna

One of the world’s few egg-laying mammals, the western long-beaked echidna lives in the highland forests of New Guinea. It uses a long, downward-curving snout and a spiny tongue to feed almost entirely on earthworms. Critically endangered, it is threatened by hunting and habitat loss.

The Western Long-Beaked Echidna (Zaglossus bruijnii) is primarily nocturnal to crepuscular, though activity patterns can shift with elevation, temperature, and human disturbance; individuals in cooler montane forests are sometimes observed foraging during cooler daylight hours. This monotreme spends the majority of daylight hours resting in self-excavated burrows, hollow logs, or dense vegetation, emerging under cover of darkness to forage across the forest floor. Like other echidnas, it is a solitary species outside of brief breeding encounters, with no evidence of pack, herd, or harem structures. Individuals maintain loosely defined home ranges that overlap with conspecifics, and there is little indication of aggressive territorial defense, likely due to low population density and the species’ cryptic, low-energy lifestyle.

Communication in Zaglossus bruijnii is not well studied due to the species’ rarity and elusive nature, but as with other echidnas, chemical cues via scent marking (from cloacal secretions) are believed to play a role in mate location and individual recognition during the breeding season. Tactile communication is limited given the solitary lifestyle, though courtship involves close physical contact, including the formation of “echidna trains” where multiple males follow and jostle around a single female. The species’ most notable adaptive behavior is its formidable digging ability: robust forelimbs and curved claws allow it to excavate soil and rotting logs in search of prey, and when threatened, it can rapidly dig straight down into the substrate, leaving only its spines exposed as a defense mechanism—a strategy far more effective than fleeing given its slow, deliberate movements.

Zaglossus bruijnii is a specialized insectivore, though its diet is more accurately described as vermivorous, with earthworms constituting the overwhelming majority of intake, supplemented by termites, ants, and other soil-dwelling invertebrates. Foraging occurs by probing leaf litter, rotting logs, and moist forest soil with its elongated, slender snout, which houses electroreceptors capable of detecting the faint bioelectric signals generated by prey movement underground. The echidna uses its long, sticky tongue—which can extend significantly beyond the snout—to draw prey into its mouth, where food is ground between the tongue and horny spines lining the roof of the mouth, as the species lacks teeth entirely.

Metabolically, Zaglossus bruijnii exhibits one of the lowest body temperatures and metabolic rates among mammals, an adaptation that reduces caloric demand and allows it to survive on the relatively low-yield diet of earthworms. This slow metabolism also permits extended periods of inactivity or even short bouts of torpor during unfavorable conditions. Seasonal dietary shifts are not well documented but are presumed to track earthworm and invertebrate abundance, which fluctuates with rainfall and soil moisture in New Guinea’s tropical highland forests. Water dependency is moderate; the species obtains much of its hydration from prey items and moist forest substrates, reducing the need for frequent direct water intake.

Breeding in Zaglossus bruijnii is believed to occur during the austral winter months (approximately June to September), based on limited field observations and comparisons with the better-studied short-beaked echidna. The mating system appears to be promiscuous, with multiple males forming “echidna trains” behind a single receptive female, competing for mating opportunities over several days or weeks. As an egg-laying mammal (monotreme), the female undergoes a brief gestation period of roughly 21-28 days before laying a single soft-shelled egg, which she transfers directly into a temporary, seasonally developed pouch-like skin fold on her abdomen.

The egg hatches after approximately 10 days, producing an underdeveloped, larval-like offspring called a “puggle.” The puggle remains in the mother’s pouch, nourished by milk secreted from specialized mammary patches (as echidnas lack nipples), until its spines begin to develop—typically around 45-55 days—at which point the mother deposits it in a burrow and visits periodically to nurse. Weaning occurs at approximately 6-7 months of age. Sexual maturity is reached slowly, estimated between 5 and 10 years, contributing to the species’ naturally low reproductive rate and slow population recovery potential.

The Western Long-Beaked Echidna faces severe and mounting threats, chief among them habitat loss and fragmentation driven by logging, agricultural expansion, and mining across its restricted range in the Indonesian provinces of Papua and West Papua. Historically confined to lowland and montane forests, the species has been pushed into increasingly higher, more remote elevations as accessible habitat is converted or degraded. Compounding this pressure, subsistence and commercial hunting remain significant threats; the species is highly prized as a traditional food source and cultural item by local communities, and its slow movement and defensive “freeze and dig” behavior make it exceptionally easy for hunters and trained dogs to capture.

Climate change poses an emerging but poorly quantified risk, as shifts in rainfall patterns could affect soil moisture and earthworm availability, directly impacting the species’ primary food source. Natural predators are limited due to the echidna’s spine-covered defense, though introduced dogs have become effective hunters of the species in areas of human settlement. The species is listed as Critically Endangered on the IUCN Red List, and conservation initiatives include CITES Appendix II protection, the establishment of protected areas such as the Foja Mountains and Cyclops Mountains Nature Reserves, community-based conservation and education programs led by organizations like Save Our Species and the Zoological Society of London (ZSL), and ongoing camera-trap surveys aimed at confirming population strongholds and informing habitat protection priorities.

• Electroreception in a Mammal: Zaglossus bruijnii possesses electroreceptors in its snout, an extremely rare sensory adaptation among mammals that allows it to detect the faint electrical signals produced by the muscle movements of buried prey.
• Egg-Laying Mammal: As a monotreme, this species lays a single soft-shelled egg rather than giving live birth, placing it among only five living mammal species worldwide capable of doing so.
• Named After a Naturalist: The species epithet “bruijnii” honors Anthonie Augustus Bruijn, a 19th-century Dutch trader and naturalist who collected specimens in New Guinea.
• Feared Extinct, Then Rediscovered: After decades without confirmed sightings, camera-trap footage in 2023 from the Cyclops Mountains provided the first photographic evidence of the species in over 60 years, reigniting global conservation interest.
• Extremely Low Metabolism: This echidna has one of the lowest body temperatures (around 32°C) of any mammal, an adaptation that conserves energy given its low-calorie earthworm diet.
• Living Fossil Lineage: Echidnas and their monotreme relatives diverged from other mammals over 180 million years ago, making Zaglossus bruijnii part of one of the most evolutionarily ancient mammalian lineages still alive today.
• Formidable Spines and Digging Defense: When threatened, the species can dig vertically into soil within moments, leaving only its dense coat of spines exposed—an effective defense against most predators, though not against human hunters.