Consider: the Pekapeka

Note: Consider Nature contains some strong language and adult themes which may be inappropriate for younger readers. Reader discretion is advised.

Islands are often bastions for Earth’s weirdest and most-unique animals. Geographically isolated by vast swaths of ocean, island animals often develop completely differently from their counterparts on the mainland, adapting to their very specific local environments. Islands often possess fewer terrestrial predators compared to mainland ecosystems, as most of them aren’t particularly motivated to swim out into the vast, deadly nothingness of the sea in the hope of maybe finding an island filled with dodos or giant tortoises to snack on (though of course, humans made short work of both). As such, many traditional prey species like birds and reptiles become larger and more docile than their mainland counterparts when they move to island ecosystems.

Even among island ecosystems, though, New Zealand stands out. The ranks of the archipelago’s wildlife include baseball-sized crickets, reptiles older than the dinosaurs, parrots smart enough to dismantle satellite dishes, and more species of flightless birds than any other place on Earth. This menagerie of bizarre animals developed in part due to a fascinating quirk of New Zealand’s natural history: until the Māori people arrived around 1300 AD, no large mammals had ever lived there. In fact, prior to human migration, the only group of mammals to have colonized New Zealand were the microbats. But these are no ordinary bats: they are the world’s only terrestrial, ground-foraging bat species. Consider: the pekapeka. Mystacina tuberculata.

Look at those lil’ teefers! He looks like a first grader on picture day. Source: New Zealand Department of Conservation

The pekapeka (also known as the Lesser Short-Tailed Bat, but pekapeka is the Māori term) is one of three species of bats native to New Zealand. As microbats, pekapekas are quite small, generally weighing 12-15 grams (0.42 - 0.5 ounces), or slightly less than a standard dino nugget. They have short, velvety fur, large ears, upturned pig-like noses, and a circle of whiskers on their faces that distinctly resemble Jamie Hyneman’s mustache. Like all bats, they have wings composed of thin, leathery flaps of skin stretched between the elongated bones of their front limbs. A pekapeka’s wingspan is about 300 mm (11 inches).

Pekapekas spend more time on the ground than any other bat species on Earth. While they can fly and will catch insects midair, pekapekas prefer to dig through the humus and leaf litter of the forest floor to find their next meal. Most bats can't even walk with their wings, much less dig, but pekapekas have a unique method of folding their wings which strengthens them and prevents their thin membranes from tearing. This anatomical change makes pekapekas one of only two bat species on Earth capable of true walking (the other is a species of vampire bat). While digging around in the leaf litter, the mustache of whiskers on their faces helps pekapekas sense prey where their other senses would fail them.

By folding their wings and tail membranes, pekapekas can strengthen their wings well enough to be used as forelimbs for walking, climbing, and digging. Image credit: Colin O’Donnell, under CC BY-SA 4.0.

Pekapekas are omnivores, with a wide-ranging diet. They eat insects, of both the flying and burrowing varieties, and in captivity will eat basically any bug presented to them. Beyond munching on bugs, though, pekapekas have several adaptations for feeding on nectar and pollen. They have particularly long tongues (for a bat the size of a jalapeño) which can fit deep into the nooks and crannies of flowers to slurp out nectar (I wonder what else that mouth can do...). Pekapekas are the only microbats known to eat fruit, and they will gorge themselves on perching lily berries when they ripen in the early autumn. They are voracious eaters, capable of consuming up to 40% of their own body weight each night (much like I did when I was banned from Golden Corral for taking “all you can eat” a little too seriously).

Their appetites for nectar and pollen make pekapekas important pollinators for a variety of plants, including several species of epiphytes. Also known as air plants, epiphytes grow on the surfaces of trees and derive their water and nutrients from the air around them. Pekapekas eat the fruit of these epiphytes and act as seed distributors for them, shitting out seeds all over the forest to help spread the plants (meanwhile, when I’m caught shitting all over the forest, I’m just arrested for public indecency). Pekapekas are also an important pollinator of the wood rose, Dactylanthus taylorii, called “Te Pua o Te Rēinga” (meaning “Flower of the Underworld'') in the Maori language. This eerily-beautiful flower is the only parasitic plant native to New Zealand. It has neither leaves nor roots of its own, instead obtaining all of its nutrients by invading the roots of trees. The place where these hell-roses invade tree roots grow into wide, flat disc shapes which were once collected as curios. Wood roses are endangered (due to the aforementioned curio collection) and as such pekapekas provide a crucial service in helping to protect these plants from extinction.

In addition to having no roots or leaves, wood roses possess no chlorophyll, causing them to appear an ethereal, ghostly white. This same phenomenon is observed in other parasitic plants, such as the ghost pipes of Asia and the Americas. Image credit: New Zealand Department of Conservation, under CC BY-SA 4.0.

When mating time comes, male bats gather in large groups called leks to sing and attract a female. To humans, these songs sound like a box of low-battery smoke detectors, but they are actually quite nuanced, with a wide range of pitches from within the human hearing spectrum into the ultrasonic range. It’s kind of like if Tinder was suddenly invaded by a massive and extremely horny all-men’s choir. In order to impress a female, males will fight over particularly good singing posts (also like Tinder). When a female finds a singing male who she likes, she approaches and the mating begins. A male pekapeka’s penis is 6 millimeters (about a quarter inch) long. I know this because B.D. Lloyd published a description of the species in 2001 where he measured the bat’s penis. Thank you, B.D. Lloyd, for cursing me with this knowledge and all of the horrible, intrusive questions it has afflicted me with. Are these bats growers or showers? Do you think they’re self-conscious about how their tongues are only one millimeter shorter than their dicks? How do you get university funding to go out into the forest and measure bat penises?

Highly-social animals, pekapekas nest in large summer colonies which can have up to 6,000 individuals, though they split off into smaller groups during the winter months. Pekapekas nest in the hollows of ancient trees within New Zealand’s old-growth forests, trees which can be two to four hundred years old. The bats often carve these roosts themselves, using their teeth to scrape tiny shavings off of the walls of their hollows and slowly widen them (I hope they have good dentists). The bats often rotate between colonies throughout the year, and have re-used some of the same roosts for centuries. As such, the trash piles up—researchers have noted piles of guano (bat poop) up to a meter thick found on the forest floor beneath the oldest roosts. While humans generally consider shitting on your next-door neighbor's lawn a felony, this process actually helps to recycle nutrients from what the bats eat back into the soil, including lots of wood from all that shaving.

Pekapekas roost in massive colonies of up to 6000 individuals during the summer months. The bats will, however, occasionally spend a night alone outside of a roost. I certainly sympathize with those lone sleepers—imagine how foul those roosts must smell. At least the bats don’t have to worry about their roommates hogging the bathroom. Image Credit: New Zealand Department of Conservation.

Pekapekas pose an interesting evolutionary question to scientists: no other bat species on Earth spends as much time on the ground as the pekapeka does—why does this bat do things differently? The answer comes in the form of the bizarre ecology and geography of the islands on which pekapekas live. New Zealand formed 25 million years ago as the fault line between the Australian and Pacific plates began to split apart. A portion of that crust, stuck in the crossfire of its parents’ messy divorce, rose to the surface of the ocean, becoming New Zealand. This remote and relatively recent formation means that no land bridge on which large terrestrial animals could cross ever connected the island to the Australian mainland. As such, the island was colonized primarily by animals that could swim or fly.

With an absence of large mammals, birds, reptiles, amphibians, and arthropods came to rule New Zealand, and over time they evolved into forms more suitable for their new homes. No large mammals on the islands meant no large land predators, and so some airborne animals didn’t need to rely on flight to escape predation anymore so long as they stayed in forested areas where native birds of prey didn’t live. Over time, a handful of bird species, such as the kiwi, kākāpō, weka, and takahē all lost the ability to fly because it no longer conferred an evolutionary advantage.

Pekapeka can fly though. They just choose not to. How come? Flying is energetically-intensive, and that means that flying animals need more energy than ground-dwelling animals to survive. Pekapekas already eat close to half of their body weight each night, so relying less on flight allows them to conserve energy. In most habitats, a terrestrial bat is just begging to be munched on by cats, rodents, or a penis-measuring human scientist, but with none of these to worry about, pekapekas could ground-forage safely. Over time, this behavior became hard-wired into the species via genetics or social learning, and their physiology adapted to accommodate this new lifestyle through natural selection.

New Zealand is home to 11 species of flightless birds, more species than any other place on Earth. Here are some of my favorites. Left to right, top to bottom: Tokoeka, also known as the Southern Brown Kiwi (Apteryx australis), Little Blue Penguin (Euydyptula minor), Kākāpō (Strigops habroptila), Weka (Gallirallus australis), and Takahē (Porphyrio hochstetteri). Despite New Zealand's reputation as a bastion for flightless birds, four of these five species now face extinction (the penguin is safe for now). Image sources: Allie Caulfield under CC BY-SA 2.5, Tanya Dropbear (who ever said image attributions couldn't have jokes?) under CC BY-SA 2.0, New Zealand Department of Conservation (DOC), Bassar under CC BY-SA 4.0, Public Domain

With no experience dealing with mammalian predators, the arrival of invasive rodents, felines, and marsupials spelled doom for many of New Zealand’s species, the pekapeka included. The first of these invasive species came in the form of the Polynesian brown rat, which arrived in New Zealand with the Maori. Over five hundred years later, Europeans arrived and introduced black rats, brushtail possums, stoats, and half a dozen more mammalian land predators to the islands. This has led to the endangerment or extinction of many of New Zealand’s species, including 10 out of its 11 species of flightless birds. Pekapekas are currently listed as Vulnerable by the International Union for the Conservation of Nature (IUCN), and currently only occupy 30% of their native range.

Rats specifically pose a major threat to pekapekas. With their excellent climbing abilities, rats can easily infiltrate pekapeka roosts. Since pekapekas evolved in a habitat without predators, they aren’t well equipped to defend themselves, and the rats go to town like preschoolers with a Chick-fil-a chicken nugget catering box. Pekapekas also hibernate over the winter, putting themselves in a vulnerable position. When rats arrived on New Zealand's Titi Island, the pekapeka population there completely vanished, and removing rats from Codfish Island restored their local bat population. Feral cats also hunt pekapekas, and have a particular talent at plucking them out of the air as they leave their roosts. A 2011 study found that a single feral cat in the forests on the southern slopes of Mount Ruapehu killed over 102 pekapekas in a short period of time.

A rogue’s gallery of some of the most-threatening mammalian predators introduced to New Zealand by humans. Left to right: brushtail possum (imported to be harvested for their fur), stoat (imported to hunt invasive rabbits in a failed attempt at biological control), black rat (introduced by European ships), and the domestic cat (yes that is Grumpy Cat, may he rest in peace). Image Sources: Brisbane City Council under CC BY-SA 4.0, Steve Hillebrand Public Domain, Avinashmaurya under CC BY-SA 3.0, Gage Skidmore under CC BY-SA 2.0.

Land clearing for timber and agriculture also threatens pekapekas. Two-thirds of New Zealand’s forests have been clear-cut since the arrival of Europeans, completely remaking much of the country’s landscape. While modern reforestation efforts have begun to restore some of this cleared land, pekapekas roost in ancient trees that take centuries to grow. Unless someone can pull a time machine out of their ass, reforestation doesn't actually accomplished much for pekapekas. The clearing of these ancient forests also poses a risk to our planet’s climate, as the carbon stored by trees is released when they are killed or when their wood is burned. Altogether, New Zealand’s old growth forests store an estimated 1.8 billion tons of carbon, almost twice as much carbon than is emitted by commercial aviation every year. Harvesting those trees would not only devastate the habitats of many species, the pekapeka included, but would further exacerbate the effects of climate change. To protect these forests, the New Zealand Ministry for Primary Industries (MPI) has placed limits on how many trees can be felled and requires logging companies to develop a sustainable forestry management plan, which the MPI must approve.

If the pekapeka were to go extinct, it wouldn’t be the first time New Zealand has lost a bat species. Three species of bat could once be found in New Zealand: long-tailed bats, pekapekas, and greater short-tailed bats. No one has seen a greater short-tailed bat since 1967, and most scientists believe that they have gone extinct. These bats lived only on two small islands off the coast of Stewart Island in southwestern New Zealand. Like pekapekas, greater short-tailed bats were preyed upon by invasive rats. It took two years from the time black rats were introduced to the greater short-tail’s islands for the species to completely vanish.

Caption: This was the New Zealand Greater Short-Tailed Bat, the closest relative to the pekapeka and one of New Zealand’s three bat species. It’s gone now. I…don’t have any jokes this time. It's just sad. Image credit: Auckland Museum, under CC BY-SA 4.0.

How do we keep history from repeating itself with pekapekas? Researchers have focused primarily on protecting New Zealand’s wildlife by exterminating invasive species. Trapping operations across the country have killed thousands of invasive rats, cats, possums, and stoats. The trapping armory of New Zealand’s Department of Conservation (DOC) runs the gambit from your run-of-the-mill Victor snap traps to high-tech carbon monoxide tunnels and electrified plates. A whole culture has sprung up in New Zealand around destroying these invasive species, including Squashed Possums, a chocolate-coconut novelty candy with a picture of a road-killed cartoon possum on the front (which you can buy here). Predator-Free 2050, a DOC initiative, seeks to rid New Zealand of invasive mammalian predators within the next 27 years.

While useful in backyards, parks, and other well-patrolled areas, traps don’t quite fit the bill when you are trying to eradicate every last rat, cat, and possum across eight million hectares of remote forest. As such, Predator-Free 2050 makes frequent use of 1080, a rat poison. Designed in 1942 by the United States National Defense Research Committee’s chemical weapons division (seriously), 1080 is a fluoroacetate salt derived from several different species of plants found in northern Africa. Once consumed and absorbed into the bloodstream, fluoroacetate is converted into fluorocitrate, an acid which interrupts the process cells use to convert sugar into energy. Most animals that ingest 1080 die within 48 hours, generally of heart or respiratory failure. The New Zealand DOC deploys 1080 in massive airdrops over forest regions, with the hope that the bait will kill as many mammalian predators as possible.

While carpet bombing a land full of endangered species with rat poison sound fucking bananas, there’s a method to the DOC’s madness. 1080 is extremely effective against the exact kinds of invasive species that terrorize New Zealand’s wildlife. Scents and colorings can additionally be applied to the bait to make it unappetizing to local birds, lessening collateral damage. But bats are mammals, not birds—how does 1080 affect our beloved pekapekas? To answer this question, 1080 drops were performed over Eglinton Valley on New Zealand’s South Island in 2014 and 2016. Populations of both pekapekas and long-tailed bats had been closely monitored in the valley since 1997, so researchers could monitor their changes over time. The 1080 drops corresponded with increases in the populations of both bat species, a sign that the poison does more good than harm at the least.

Basically everyone in the worldwide conservation community agrees that 1080 is an imperfect solution, the DOC included. As a poison, 1080 causes some suffering in the animals that ingest it, especially possums. The poison is also exceptionally toxic to dogs, even more so than it is to rodents, causing them fatal and extremely painful convulsions reminiscent of epileptic seizures. Poisonous chemicals can also leech into bodies of water, damaging the ecosystem or polluting drinking water. The DOC’s position is that, while dangerous and somewhat inhumane, 1080 is the only way to protect New Zealand’s wildlife from eradication. A variety of controlled studies have proven 1080 to be effective in species conservation. One such study found that in areas containing invasive predators, only 5% of kiwi chicks survived to adulthood. With the application of 1080, 60% of chicks survived. Research has also shown that 1080 quickly biodegrades in water, so it is unlikely to contaminate lakes, rivers, and reservoirs. Amphibians, reptiles, and arthropods also have a very low sensitivity to 1080 bait, so it is unlikely to harm them if ingested.

How far should we go to protect endangered species? Is causing suffering to thousands of animals worth it if doing so will protect an island chain’s unique ecosystems? After all, it’s hard to truly blame the individual invasive predators for the havoc they’ve wreaked across a land where they didn't mean to be and didn't ask to go. Is the evidence of 1080’s harmlessness to the environment sufficient to ensure there won’t be collateral damage? Personally, I love the pekapeka and its community of ground-dwelling neighbors. It would break my heart to see a species as special as this one confined to zoos or museum specimen collections. I believe that humans have a moral responsibility to mend what we’ve broken when it comes to our climate and our ecosystems, whatever it takes. I hope that while hawks and eagles and parakeets will soar in the sky above, the humble pekapeka will burrow through the mud and the undergrowth for many centuries to come.

Sources and More Information:

• Boyes, B. 2006. Mystacina robusta. Animal Diversity Web.

• Eglinton Valley lesser Short-Tailed Bat Monitoring Programme. New Zealand Department of Conservation

• Geology—Overview. Teara, the Encyclopedia of New Zealand

• History of New Zealand 1769-1914. NZ History

• Holdaway, 1998. Grounded! Why do Some Birds Walk? New Zealand Geographic.

• Lloyd et al., 2001. "Advances in New Zealand mammalogy 1990–2000: Short‐tailed bats". Journal of the Royal Society of New Zealand (also thank you Dr. B. D. Lloyd for the work you have done to describe this species—sorry for making fun of you)

• Overton, 2022. "Issue Brief | The Growth in Greenhouse Gas Emissions from Commercial Aviation (2019, revised 2022)". Environmental and Energy Study Institute

• New Zealand Lesser Short-Tailed Bat. Zoological Society of London EDGE of Existence

• Paul et al., 2021. "Natural forests in New Zealand – a large terrestrial carbon pool in a national state of equilibrium". Forest Ecosystems

• Protecting New Zealand's Forests. New Zealand Ministry For Primary Industries

• Rare Species: Short-Tailed Bat. New Zealand Forest Owner's Association

• Roach, 2021. "Fuzz: When Nature Breaks the Law". W.W. Norton & Company Publishing. (I cannot recommend this book enough. It is really influential for me).

• Science Learning Hub, 2018. "The Chemistry of 1080". Pokapū Akoranga Pūtaiao

• Scrimgeour et al., 2011. "Cat predation of short-tailed bats (Mystacina tuberculata rhyocobia) in Rangataua Forest, Mount Ruapehu, Central North Island, New Zealand". New Zealand Journal of Zoology

• Short Tailed Bat. New Zealand Department of Conservation

• Why We Use 1080. New Zealand Department of Conservation

Video Resources:

• Great News For Pekapeka! | New Zealand Nature News. New Zealand Department of Conservation

Consider Nature is written and published by Stephen Goralski. Editors for this article included Benjamin Gamble, Jesse Cristoforo, and Oli Platt. Our web designer is Oli Platt. Olmungandr, the Consider Nature logo, was made by Maxwell Schumacher.

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Does anybody else remember Chick-fil-A being spelled "Chik-fil-A"? Must be some Mandela Effect shit. Anyways, Royal Farms' chicken sandwich is better, and you can add Old Bay mayo to it (and also RoFo isn't run by homophobes).

Jesus Christ I wanna snort a line of Old Bay and feel the salt in my brain.