Night hikes might more aptly be described as slow walks rather than hikes. The campus trails that students get to know by day harbor completely different ecological communities at night.
Colorful, vocal, mixed-flocks of birds retire to their roosts as bats take their turn to forage for choice fruits and insects. We usually preface our hikes with some information about the species we are likely to encounter, sounds we are likely to hear, and how to spot eye shine. We never know what we are going to see, but we usually expect to hear a chorus of cricket and katydid stridulations, punctuated by the chirping of bats. Night hikes are exercises in patience as a dozen flashlight beams scan the forest floor, dense surrounding foliage, and upper canopy for the creatures of the night. As much as everyone (naturalists included!) would love to see an olingo, kinkajou, sloth, or family of bats, it is important to remember that it is the elusive nature and cryptic colorations of many nocturnal species that enhances their survival in this ecosystem of abounding predators and prey. We expect to see some animals on every hike- usually some of the six-legged varieties- but sometimes you just get lucky!
On Saturday night (March 1st) I led a group of students from Steller Secondary School in Anchorage, Alaska. Our walk began with a silent passage through the small banana forest on the Cecropia Trail. The leaf-cutter ants were quite active, in spite of the wind and the rain, and we carefully stepped over leaf-cutter ant highways that cross-cut the trails. Eda, our resident Orange-kneed Tarantula, was in her rock cave near the fork of the Sendero Cecropia and Sendero Buho. Orange-kneed Tarantulas (Brachypelma smithi) are indigenous to the tropic and subtropic regions of Central and South America. This particular species is sexual dimorphic. We know Eda is a female because she is has a dark brown coloration and bright orange bands around her legs and abdomen; males have lighter brown or gray bodies with duller orange bands. In contrast to many web-spinning spiders, Orange-kneed Tarantulas are nest builders and prefer to make their homes on the ground in rock caves or piles of leaf litter, from which they can catch the unsuspecting beetle, ant, or small arthropod and hide from predatory army ants and hawk wasps. Despite their frightening appearance, they are relatively harmless and shy. Their first line of defense is to runaway and hide. If seriously threatened, they will rear up on their hind legs and flick urticating hairs from their abdomen at the antagonist. Biting is an expensive, last resort and their bite is less potent than a bee sting. “No one has ever died from a tarantula bite,” I say as we leave Eda’s hideaway.
We found a sleeping, pot-bellied bird with its head tucked snuggly behind its wings, bobbing up and down, seemingly unperturbed by the movement, at the end of a branch. Contrary to what one might think, many birds deliberately sleep at the end of a branch, far from the trunk of the tree. They do this to put more distance between themselves and any snakes which might be lurking around the trunks or at the base of tree limbs. Farther along the trail I found a Phasmid- stick insect – which crawled around my jacket and passed from palm to palm as students held up the insect for closer inspection. Stick insects are one of the quintessential examples of cryptic camouflage. In addition to looking like twigs, some species are able to alter their colorations to blend into their surroundings like a chameleon. Returning our phasmid to his post, we moved on to the Casita Trails where Steller students spotted many crickets and katydids, all of differing sizes and colors. As we entered the Casita Trails, we also stumbled upon a Swainson’s Thrush (Catharus ustulatus) perched at eye level on a bush. These are migratory birds that spendmost of their non-breeding, winter months in Central and South America, spending most of their time unseen, rummaging for insects in the understory. Later in our walk we found a Wood Thrush (Hylocichla mustelina). From afar, the Wood Thrush looks similar to the Swainson’s Thrush. At a mere arm’s length away, however, we could see that the Wood Thrush has a starker white belly with more pronounced dark brown spots and a reddish-brown back. The Swainson’s Thrush’s speckled belly is more subtle and its back and wing feathers have a more cinnamon hue.
Turning toward the moth wall – a hallow of light in otherwise impenetrable darkness – we found an iridescent green beetle with red legs, moths of varying sizes, five glass winged butterflies and a blue morpho butterfly. As students peered through the translucent wings of the butterflies, the brown and seemingly nondescript blue morpho took flight, its wingbeats revealing its brilliant blue coloration.
The coup de grace of Saturday’s night hike was spotting a male and female pair of Orange-bellied Trogons (Trogon aurantiiventris aurantiiventris) perched in a thicket over-hanging the trail. The male has a vibrant orange belly separated by a white line from its dark black-green head and neck. Its long, squared-off tail feathers are one of his most eye-catching features, displaying a horizontal pattern of black and white striations. The female has a paler orange belly and brown head and back. Our close proximity allowed us to see her elliptical white eyeing and yellow beak.
Endemic to Costa Rica and western Panama, this species is commonly found between 700-2300m in northwestern Costa Rica. Trogons are secondary cavity nesters. Lacking the ability to bore holes in trees, they use tree cavities made by woodpeckers. Preferring the lower canopies of secondary and disturbed forests, trogons feed on a variety of fruits and insects. They are sally-glean foragers, meaning they will leave their perch to snatch an insect or fruit and return to their perch, using their heavily serrated bills to chew their meals. Trogons are among the most colorful and, arguably, most beautiful birds in the Neotropics.
Saturday night’s excursion was a testament to the sheer diversity of life in our premontane humid forest life zone. I am glad I was able to share this experience with so many enthusiastic students and budding naturalists. Thank you!
Blog contribution by Hannah E. Durick, UGACR Resident Intern Naturalist
Photo Credit: Jonas Banta, Steller Secondary School Group, Alaska