Candid Creatures: How Camera Traps Reveal the Mysteries of Nature

Candid Creatures

HOW CAMERA TRAPS REVEAL THE MYSTERIES OF NATURE

Candid Creatures

ROLAND KAYS

© 2016 Johns Hopkins University Press

All rights reserved. Published 2016

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Library of Congress Cataloging-in-Publication Data

Names: Kays, Roland, 1971–. author.

Title: Candid creatures : how camera traps reveal the mysteries of nature Roland Kays.

Description: Baltimore : Johns Hopkins University Press, 2016. | Includes bibliographical references and index.

Identifiers: LCCN 2015017512 | ISBN 9781421418889 (hardcover : alk. paper) | ISBN 9781421418896 (electronic) | ISBN 1421418886 (hardcover : alk. paper) | ISBN 1421418894 (electronic)

Subjects: LCSH: Animals—Pictorial works. | Animals. | Animal behavior—Pictorial works. | Wildlife photography.

Classification: LCC QL46 .K39 2016 | DDC 590—dc23 LC record available at http://lccn.loc.gov/2015017512

A catalog record for this book is available from the British Library.

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To

Judy,

Eli, and

Fletcher

CONTENTS

Acknowledgments

INTRODUCTION

THE CRITTERS

Tiger

African Lion

Leopard

Snow Leopard

Jaguar

Cougar

Clouded Leopards

Cheetah

Bobcat

Chinese Mountain Cat

Domestic Cat

Flat-headed Cat

Leopard Cat

Marbled Cat

African Golden Cat

Jaguarundi

Ocelot

Fossa

Spotted Fanaloka

Ring-tailed Vontsira

Broad-striped Vontsira

Servaline Genet

Masked Palm Civet

Otter Civet

Hose’s Civet

Banded Civet

Wolf

Coyote

Dingo

Dhole

Red Fox

Bush Dog

Short-eared Dog

Black Bear

Brown Bear

Giant Panda

Spectacled Bear

Sun Bear

Wolverine

Fisher

Tayra

Malay Weasel

African Bush Elephant

African Forest Elephant

Asian Elephant

Black Rhino

Javan Rhino

Brazilian Tapir

Malayan Tapir

Bearded Pig

Pygmy Hippopotamus

Giant Sable Antelope

Tamaraw

Asiatic Wild Water Buffalo

Alpine Ibex

Southern Pudú

White-tailed Deer

Chimpanzee

Western Gorilla

Bornean Orangutan

Golden Snub-nosed Monkey

Pig-tailed Macaque

Aardvark

Giant Armadillo

Giant Anteater

Giant Pangolin

Wombat

Tasmanian Devil

Sumatran Striped Rabbit

Thomas’s Flying Squirrel

Common Vampire Bat

Sumatran Ground Cuckoo

Black Cod

ANIMAL NEIGHBORHOOD WATCH

Chinese Mountains

Panama Canal Islands

Australian Rocky Reef Fish

Rainforest Canopies

The Wildlife of Tokyo

America’s Urban Predators

The Foggy, Forested Hills of Yemen

Cattle and Wildlife in Africa

Rocky Mountain Trails

America’s Hunting Grounds

Gaps in the Polish Woods

Oil Palm Plantations

CAUGHT IN THE ACT

Holes in the Ground

Water Holes

Movement Corridors

Treetop Corridors

Road Underpasses

Electromats

Fence Escape Routes

Highway Rope Bridges

Glide Poles

Nest Predators

Nest Protectors

Carcasses

Mineral Licks

Fruiting Trees

Bush versus Elephant

Buried Seeds

Animal Robots

Animal Models

Surfing Genet

Food on the Run

Mating

Poachers

Photo Credits and Citations

Literature Cited

Index

ACKNOWLEDGMENTS

First and foremost, I am completely indebted to the hundreds of camera trappers who shared their photographs and discoveries with me. This book could never have happened without their hard work in the field setting many thousands of camera traps around the world. The 613 photographs come from 153 different research groups, many of which represent large teams, meaning that many thousands of people helped run the cameras that generated the photos and discoveries featured here. Hiking through the woods to the next camera is only part of the work; these camera trappers also sorted through many millions of photographs, tabulating each as a data point for their research and saving just a few in their folder of greatest hits. They graciously shared these collections of their best photos with me, from which I picked the very best that I could find to tell the stories of their discoveries.

This book is more than just pretty pictures—it also represents a summary of the scientific discoveries and conservation accomplishments of these research projects. The literature cited has 240 citations referencing the scientists’ original work, which I have tried to summarize in the text, graphs, and maps. I am grateful to many colleagues who were willing to share preliminary results or raw data to help me accurately represent their latest discoveries. I also am greatly indebted to the staff and volunteers of the eMammal project, a citizen science camera effort that I work with, which contributed many photographs and findings. Eric Knisley helped convert some of this science into art by creating the original artwork in the Animal Neighborhood Watch section. Many thanks to him for his creativity and patience to make sure the pieces were both accurate and interesting.

A number of people helped read the text, and their attention greatly improved the accuracy and flow of the writing. Thanks for reviews from Laila Bahaa-el-din, Danielle Brown, Iain Gilby, Matt Gompper, Klaus Hacklaender, Patrick Jansen, Judy Kays, John Perrine, Robin Sandfort, and Stephanie Schuttler. Three undergraduate students from North Carolina State University helped with the early phase of this book; thanks to Summer Higdon, Rebecca Owens, and Gabriella Quinlan for their research and ideas. Thanks to Kathryn Marguy and Vincent Burke at Johns Hopkins University Press for helping bring this book to fruition. Finally, thanks to my family, Judy, Eli, and Fletcher, for helping me run cameras and chase critters.

Candid Creatures

Introduction

The world is alive with animals that we virtually never see with our own eyes. Most wildlife, especially mammals, hear or smell us long before we see them. Some hide out in holes or thickets as we pass by. Others run away to avoid us before we can catch a glimpse. Many species are nocturnal, starting their activity right when we are winding down our day, hiding under the cover of darkness. The rarest and most elusive species live in remote corners of the world that are difficult to access.

The near impossibility of seeing some wildlife species frustrates nature lovers and exasperates zoologists. How can we study or count animals we can’t see? Some are rare and listed as Endangered Species; others we know so little about we can’t assess them, instead classifying them as Data Deficient. The scientist’s solution to this problem is the camera trap—a motion-sensitive camera that can be left alone in nature to quietly record photographs of any animals that pass by.

CAMERA TRAPS REVEAL NATURE’S SECRETS

Like microscopes for microbiologists or telescopes for astronomers, camera traps give zoologists a new way to observe the subjects they study. Each of these inventions created new ways of seeing, opening windows on the natural world and leading to rapid scientific development in their fields. Not only are camera traps a unique way to look at critters, but the tool has transformed the way wildlife science is conducted and is having important implications for our understanding of these animals. The photos are translated into data, which are used to ask questions and test hypotheses. Modern studies use dozens of camera traps over hundreds of locations to collect many thousands or millions of photographs. Each image registers which species are living in a given place at a given time. The identity of the species in the photo can be checked and verified, an important part of the scientific process. Indeed, the camera trap photograph offers a way to measure biodiversity, a testament to life on earth similar to the traditional animal skins and skeletal specimens stored in the collections of our great natural history museums. These new digital libraries of camera trap photos provide a snapshot of the abundance and diversity of animal communities around the world.

An endangered Grévy’s zebra is caught on camera on a hot day in Kenya. Text at the top of the photo records the date and time, that this was the third of three consecutive photos after the animal triggered the motion sensor, and that the temperature was 100°F. The text at the bottom records the camera make and model, and sometimes a customizable code.

The stories in this book are about the discoveries made by scientists probing the secrets of nature with camera traps. The mere existence of a species, documented with a camera trap photo, can be a discovery on its own. Sometimes it can be a species new to science, or it may be the rediscovery of a rare animal feared extinct. Unique behaviors can also be documented by cameras, which wait soundlessly with more patience than any human observer possibly could. Often the discoveries come later, once the images have been converted to numbers and summed up in a database. The resulting patterns of where animals are and are not present can reveal the forces of nature, and of humans, in determining which species survive where.

Almost nothing is known about the ecology of the black-footed mongoose. Camera traps have recorded them in African rainforests, such as this one from Korup National Park in Cameroon.

Truth be told, most of the millions of camera trap images collected each year are rather boring. Camera traps capture anything and everything that triggers their motion sensor, often recording the rear end of some common mammal or a blurry shot of a small bird passing through the frame. But the mindless persistence of automated cameras and the considerable quantity of images being amassed in the name of science eventually result in some pretty amazing photographs. The memory card of each camera has at least a few good animal shots, and every camera trapper has a folder full of his or her own greatest hits. The goal of this book is to pull these few amazing photographs out of the scientific archives to show a new perspective on wildlife and to highlight the scientific discoveries they enable.

An Indian porcupine raises its quills and scurries toward safety with a tiger on its tail. Tigers generally prefer larger prey without quills, but they are known to kill and eat porcupine, presumably if they are hungry enough.

THE HISTORY OF CAMERA TRAPPING

The basic principles of camera trapping are simple. Set a camera someplace you want to monitor for wildlife, rig up a motion sensor, leave it to silently record images for a few days or weeks, and then come back to see what you got. Although the use of camera traps has skyrocketed recently, the concept has been around for more than 100 years. The inventor was a wildlife photographer from Pennsylvania named George Shiras, who used to hide in his boat and use a string to trigger his camera when deer came to the shoreline. Shiras realized he could set up his camera to have the animals pull on the same string as they walked by, thus creating the first automatic camera trap. This new kind of close-up wildlife image was hugely popular and was first published in National Geographic magazine in 1913 (in their second issue featuring photographs).

Shiras’s photographs were both curiosities and works of art. Another decade would pass until a scientist adapted the method, when Frank Chapman started using a camera trap to document the rainforest mammals of Barro Colorado Island, Panama. His photographs, published in National Geographic magazine in 1927, stand up today as not only beautiful but also useful for science. For example, his photographs prove that white-lipped peccaries were present on the island in his time, although they are now extinct at this site.

Advancement in the method was slow for another half century. The technical challenges are obvious when considering Chapman’s rainforest setup: a large-format glass plate as film and cakes of magnesium flash powder. The explosive flashes made as much noise as light and must have frightened animals for miles around. Commercially available photography equipment remained bulky and complicated for years; a 1964 article in the Journal of Mammalogy bragged that their new equipment weighed only 47 lbs.

A surprised lion looks down on an overenthusiastic jackal in Namibia. Jackals are typically a nuisance to lions, stealing scraps from the larger carnivore’s kills. This jackal’s aggressiveness suggests that it might have rabies, which would be dangerous for the entire animal community, including humans, if passed on to the lion after this encounter.

A rhesus macaque takes a walk along the river at sunset in Manas National Park, India.

Frank Chapman was an early pioneer of camera traps. He is pictured here on the porch of his lab on Barro Colorado Island, Panama, with the latest technology of the 1920s: a large-format camera with a single glass plate.

Frank Chapman used a trip wire set across the trail to trigger his camera, which had two cakes of magnesium powder wired to explode as a flash. Explosions illuminated the image well, but they were also as loud as a small cannon, according to Chapman’s notes, and certainly gave animals a fright.

By the late 1980s, 35 mm point-and-shoot film cameras had become small and inexpensive enough to create large numbers of affordable camera traps. For the first time, zoologists could send out field crews with dozens of camera traps to get the sample sizes needed for proper scientific surveys. Early pioneers of this approach include Ullas Karanth and his tiger research in India and the Pacific Northwest Research station of the US Forest Service, which used cameras to survey for lynx and wolverines. In both cases, scientists were improving on existing camera trap designs to survey species that were otherwise almost impossible to see.

The use of camera traps in scientific papers has grown rapidly in the past decade, with an annual growth rate of about 25%, which is a faster growth rate than most other scientific fields.

Around this same time, American hunters started using camera traps to scout for deer, trying to learn the movement patterns of the largest bucks to plan their fall hunts. A new crop of companies sprung up to make camera traps for the hunters, and scientists were eager to try out these lunchbox-sized units. Photos and data rolled in, and their use in scientific papers increased; a 1999 review covered 78 journal articles reporting results from camera traps, dating back to Chapman’s Panama work.

Camera trappers were probably the last group of photographers to totally switch from film to digital. Although having only 36 frames per roll of film was a huge limitation, early digital camera traps were so unreliable that most scientists decided that they just weren’t worth the time and money. Early designs weren’t completely sealed to the environment; it is amazing to see the damage that moisture and insects can wreak on electronics left tied to a tree for a few weeks, especially in the tropics. Another problem with early digital cameras was that it took them a few seconds to wake up and take a photograph once they were triggered. This trigger delay resulted in many empty frames as the moving animal passed out of the field of view before the photograph was taken.

Digital camera traps finally became field worthy by around 2008. Whereas the earlier digital equipment failures had simply wired a point-and-shoot digital camera to a motion sensor, these new companies started creating integrated systems with extra weather proofing specifically for use in camera traps. The hunter and researcher market continued to grow, and new discoveries filled the pages of journals. The number of scientific articles reporting results from camera traps has grown at a rate of about 25% per year over the past decade, with 741 articles published in 2014.

An infrared flash illuminates a gaur walking through the dark forests of Malaysia; cameras in forests with thick tree canopies often need to use flashes even for daytime photos.

CAMERA TRAPS TODAY

Although camera traps go by a variety of names (e.g., remote camera, game camera, trail camera), most have the same design, with a passive infrared (IR) motion sensor triggering a digital camera and flash inside a waterproof box that also holds the batteries and a memory card on which to save the photos. This type of motion sensor is triggered by moving heat, typically a warm-blooded animal moving through a colder environment. Other triggering devices that have been tried over the years have mostly been abandoned because of the complexity of setup and unreliability of triggering, including active IR sensors (aka break-beam or laser beam sensors), pressure pads, and a piece of string tied to bait.

A leopard walks through a paired set of cameras with white flashes. Setting two cameras facing each other allows scientists to capture both sides of an animal, which helps identify unique individuals by their stripes or spots.

Most cameras used by scientists save images to a memory card that must be retrieved to view the photos. There are networked cameras available that send the images instantly through cellular or satellite networks, but these are expensive and typically not worth the cost for a scientist who might be running dozens or hundreds of cameras. However, the live images from these cameras are quite fun and have been developed into outreach tools through smartphone apps (e.g., Instant Wild) or Twitter feeds (@CamtrapLive). A live feed can also be useful for catching poachers.

Scientists are increasingly running camera traps in video mode. This provides more detail about the animal’s behavior, although often in lower resolution than still photos. Video files also take longer to review and are harder to store and organize, which becomes a problem for larger projects.

Most mammals are nocturnal, requiring some illumination for the camera to capture a photo of them. The flashes of camera traps can be either a normal incandescent white light or an IR light. The white flash captures better photographs that are color and always sharp, whereas IR images are black-and-white and sometimes blurry (depending on the strength of the light). However, an IR flash is typically not noticed by animals, whereas the white flash has the potential to frighten animals away from an area.

A male mandrill pauses to look at the camera as it passes through the African rainforest.

A chimpanzee reaches out to touch the camera trap and triggers its motion sensor, taking an apparent selfie.

DO CAMERA TRAPS BOTHER ANIMALS?

Scientists refer to camera traps as a noninvasive survey technique because they generally don’t disturb animals, especially if they have an IR flash. Certainly camera trapping is less invasive than traditional methods that physically trap an animal. Nonetheless, some animals clearly do notice the camera. Any piece of plastic strapped to a tree in the woods would probably attract the attention of wildlife passing by just because of its novelty or unique smell. Some camera traps make faint noises or have IR flashes that glow a dull red, which might attract a bit more attention. Occasionally, animals look right at the camera or approach it for a sniff. These instances make the best photographs and so are overrepresented in this book. However, in the typical scientist’s database, such close-up photos are actually a rarity, as most animals that pass by act naturally, probably without even noticing the device.

This young jaguar has eyeshine from only one eye, suggesting that it has a damaged tapetum lucidum, possibly from some prey animal trying to defend itself.

Camera traps with white (incandescent) flashes are more likely to affect animal behavior. This isn’t surprising given the blinding effect a flash of light can have on the eyes, especially when they are adjusted for night vision. A study in India found that tigers avoided a site for five days after triggering a white flash. Scientists always want to minimize their impact on the animals they study, and thus more and more researchers are adopting IR flash cameras.

All types of camera flashes can light up the eyes of mammals looking at the camera. This eyeshine is a reflection off a layer in the back of the eye called the tapetum lucidum. This layer reflects light back through the retina, improving the collection of light and therefore the animal’s night vision, although slightly blurring the image. Humans, as well as many other diurnal animals, do not have a tapetum lucidum, but we still sometimes have glowing eyes in photographs, which is known as the red-eye effect. This phenomenon is similar to eyeshine, but in this case light reflects off a blood-rich (and thus red-colored) part of the eye known as the fundus.

A white rhino sniffs a camera trap in Kenya.

An elephant vandal is caught on one camera as it tips over the post holding up another in this paired set.

Occasionally, animals not only notice the camera but walk up and destroy it. Elephants and bears are the most problematic camera vandals. Bears are known to take advantage of the hard corners of a camera to scratch their backs, and then sometimes they chew on the camera. Elephants can easily wreck the normal plastic casing, forcing some camera trappers to reinforce their setup with metal enclosures.

CAMERA TRAP DISCOVERIES

Scientists translate the images recorded by camera traps into data that can be used to test hypotheses and answer questions about wild animals. In recent years these cameras have become one of the core methods in the field biologist’s toolbox, alongside traditional traps, tracking collars, binoculars, and mist nets. Typical motion sensors will occasionally trigger on mice or rats when they run close to the camera, although the smallest animals are difficult to identify from photographs. Most camera trap research focuses on terrestrial animals larger than a rat, which are easier to identify and more reliably trigger the cameras.

Camera traps are more difficult to secure in environments without trees. Here a mountain deer known as a taruca passes by a pair of camera traps set in the rocks in the Bolivian Andes.

The most basic question one can address with a camera trap is where a species lives. A good camera trap image can offer proof that an endangered species survives in an area, as in the case of the Angolan giant sable antelope, found by camera trap after not being documented for two decades. Likewise, photos often extend or modify the known geographic ranges of animals.

Once you know that an animal lives in the given area, the next natural question is, How many? Counting animals in person is surprisingly hard because of their amazing skills at hiding from us. Counting animals in camera trap photos is much easier. If animals have stripes, spots, or other unique marks, they can be individually identified in photographs, allowing a straightforward census of a study site. Since the right and left sides of an animal can have different patterns, camera trappers often put a pair of cameras along a trail to record both sides of each animal that walks by.

Scientists spread their cameras throughout the study area and generate photo libraries of all the known individuals, and then they translate this into a matrix of zeros and ones. This is known as a capture history, with a one indicating that a given animal was photographed on that day, and a zero showing that it was not detected. These data can then be analyzed using a method traditionally known as mark-recapture to estimate the proportion of animals counted, the proportion missed by the cameras, and thus the total number of animals in the population. Usually the goal is to estimate the density of animals (animals per square kilometer), so once the animals are counted, the next step is to estimate the size of the area covered by the camera traps. A second analysis on the spatial arrangement of the capture history can provide this component, resulting in a final estimate of the number of animals per square kilometer.

An African wild dog begins its activity at sunset. This animal is wearing a tracking collar, which allows scientists to collect more detailed data on its movement and activity.

It is safe to say that most camera trappers have spot or stripe envy, because most species recorded by camera traps are not uniquely marked and thus cannot be individually identified in photos. Tigers, spotted cats, and hyenas have patterns that are relatively easy to match up between photographs, and some species of deer have unique branching patterns in their antlers, allowing males to be counted during certain parts of the year. Unfortunately, bears, canids, female deer, and most other mammals have too little variation in their appearance to be recognized individually. In these cases, scientists can use alternatives to true counting that allow the relative abundance of an animal to be estimated and compared over