Condor Couples

Inti, the female condor. Female condors have red eyes; males' eyes are yellow.  Image by Elizabeth Deatrick
Inti, the female condor. Female condors have red eyes; males’ eyes are yellow. Image by Elizabeth Deatrick

By Elizabeth Deatrick
BU News Service

Ducking my head to avoid a shower of raindrops from overgrown foliage, I push open the heavy metal doors of the Andean condor cage at the Franklin Park Zoo. If it wasn’t so cold, the scene could have come straight out of Jurassic Park: the cage is enormous, a domed web dark against the sky. Vines stretch like cobwebs over its roof. The visitor walkway, a tube of heavy, black wire mesh with a wooden floor, stands about fifteen feet off the ground, and runs between full-grown trees and an artificial waterfall, long-since dried up.

On the damp cement and stone of the old cascade, stoops an enormous female condor: Inti, a jet-black bird who clasps her crag with dignity. Her bald head is drawn back into the white ruff of her neck. Her mate, Humphrey, hops up the cliff face to join her; as he draws close, she snaps at him.

Inti’s brief testiness does not bode well for her species. It’s rare to see a wild Andean condor these days, even in the highest mountains of Peru and Argentina. Only around 2,000 of these magnificent creatures remain in the wild, though as with many other endangered species, zoos across the U.S. are working to maintain them in captivity, with as much genetic variety as possible. Humphrey’s pairing with Inti is a result of that program; he’s been procured from the Sedgewick Zoo, in Kansas, as a replacement for an older bird, named Tito. Tito was once the most genetically valuable Andean condor in captivity, and the keepers had high hopes for him.

Condor Enclosure indoor
The visitor walkway through the condor cage. Image by Elizabeth Deatrick

Despite forming a strong bond with Inti, Tito never managed to fertilize her eggs. Year after year, Inti climbed inside the wooden nest box built into the side of the main cage, scraped out a sandy, bowl-shaped nest, and tenderly brooded a completely useless infertile egg. Even artificial insemination didn’t work: by the time the zoo tried it, Tito had aged out of his prime, and his sperm count was too low.

At six years old, Humphrey has only just entered sexual maturity. His flight feathers are still the dusky grey of a juvenile; they’ll fade to the bright white feathers of the adult male within the next year. At feeding time, Humphrey hops back and forth, waiting for another sliver of horsemeat to be shoved through the mesh. “You can see his head flush red when he gets excited,” notes Greg Stimpson, Lead Keeper of Birds for Franklin Park, as we shiver and watch the birds. I ask if Humphrey’s personality could push Inti away. Stimpson shrugs. He ruefully notes that it takes a long time for condors to form relationships (technically known as pair-bonds). “They’re South American birds, so they mate during our winter, and we got Humphrey too late. We missed this year’s mating cycle.”

Figuring out condor reproduction is a fairly urgent matter: according to a 2007 study, all wild condors are closely related to each other––which means that zookeepers much watch out for inbreeding. The Association of Zoos and Aquariums keeps tabs on where all the individuals of a given species are, how many offspring they’ve had, and how rare their genes are. This collection of records is called a studbook. Wild-caught animals have a high value in the studbook, since they might carry some genes that the captive population doesn’t. Meanwhile, animals with many siblings, whose ancestors have been in captivity for generations, are assigned a lower value.

Condor Enclosure Outdoor
The exterior of the condor cage, red with Virginia Creeper leaves. Image by Elizabeth Deatrick

The studbook may sound almost callously clinical, but several conservation success stories have proved its value. Not only does it help avoid inbreeding, but if Andean condors ever go extinct in the wild (as their cousins, the California condors, did) keeping the genetic variation of the captive population high could ease their reintroduction to the wild. If zoos are careful, the genes of captive birds will mirror those of their wild relatives. From a genetic perspective, it would be as if the wild birds never went extinct.

Luckily, Inti and Humphrey’s wild relatives are relatively safe for now. They’ve adapted to humans’ influence on their environment surprisingly well, supplementing their diet of native guanacos and rheas with goats, sheep, rabbits, and non-native deer. They’re hardy birds, capable of handling the pesticides and other toxins that we release into their environment. Case in point: few other birds could live comfortably in the cage at Franklin Park. Since 1913, when the cage was built, lead-based paint has dripped off the bars and into the soil and pools of water below. The heavy metals killed the waterbirds and macaws that once lived there, but because the old pools have been filled in and the condors don’t spend much time on the ground, they’re hardly affected by the lead contamination.

As I watch Inti and Humphrey through the wire mesh, and the theme from Chariots of Fire echoes and swells from the nearby Franklin Park racetrack, Humphrey arches his neck like a horse on parade and turns to face his mate. His wings partially unfurl, farther than my own arms can reach. His head and comb flush a deep red. His chest contracts, and he lets out a soft, hiccuping, drumming rhythm. Inti reaches out, and gently nibbles at his beak. Eventually they fall back into statuesque silence, huddled against the rain––but beside each other now, staring back at me, together.

One with the Tiger

Anala, a female tiger at the Franklin Park Zoo.

Consider the tiger. On September 23rd of 2014, at the Delhi Zoo in India, a young man either fell or jumped into the tiger pit. There, after a 15-minute standoff, the man was mauled to death.

There is some disagreement as to whether the young man intentionally jumped into the enclosure, or whether he accidentally fell in––but if he jumped, he wouldn’t be the first. Take this visitor to the Bronx Zoo, who was so determined to become “one with the tiger” that he scaled two sets of fences:

Many big cat exhibits, including those at the Delhi Zoo, use a large moat or pit to separate the animals from the visitors. This seems to work well at keeping animals in (with the notable exception of the San Francisco Zoo’s moat, where an enraged attacking tiger was able to climb out), but without additional fences, the moat does nothing to keep determined human visitors out.

There is another approach: reinforced glass walls. On the surface, these are the best of both worlds: humans and big cats can safely see and interact with each other.

But this isn’t a perfect solution: glass walls serve as both metaphorical and literal insulators. They save visitors from the creatures on the other side, but also keep them from connecting with the animals on such a visceral level. Sounds are muffled, and smells blocked. Photos of the animals come back with glare and smudges. Furthermore, it costs a great deal to renovate an exhibit.

By contrast, in an open-air moat design, visitors can feel as if there is nothing between them and the majestic cats. Photos come out crystal clear, and any sounds the cats make are clearly audible. Even fences, of various types, allow for visitors to hear the cats clearly, even if the bars get in the way of pictures.

This sense of being in the same space as a wild animal is vital––it’s one of the main functions of modern zoos, since visitors are less likely to care about, and learn about, and save animals that they feel no connection to. Moreover, we hunger for this connection. But until visitors can be trusted to keep themselves on the right side of the barriers, however, zoos will be forced to weigh safety against education.

A warning on the tiger cage at the Franklin Park Zoo.
A warning on the tiger cage at the Franklin Park Zoo.

Bad News for Big Babies: The Elephant Fertility Crisis

Photo credit to Wikimedia Commons
Photo credit to Wikimedia Commons

By Elizabeth Deatrick
BU News Service 

Baby elephants are among the most adorable infants of the animal kingdom, with their oversize floppy ears, tiny soft eyes and fuzzy rounded backs. But despite their popularity in American zoos, these babies are all too rare: Captive elephants are facing a population crash. In the early 1990s, instead of importing more elephants from the wild, zoos began breeding their own, and it didn’t take long to realize that only a few elephants were fertile. Even today, researchers are still figuring out why.

For every five Asian elephants that die in captivity today, only three are born. And the birth rates are only slightly better for African elephants. The problem isn’t just one of numbers: each time an elephant dies without reproducing, its genes disappear. American zoos already have a very small population of elephants, and losing any diversity means inbreeding becomes more likely. After too many generations of mating with their close relatives, the elephants’ offspring will eventually become sickly and prone to disease. Zoos have thirty years before the elephants start to become inbred. If the problem isn’t solved in fifty years, elephants in captivity will go extinct.

Zoos often portray themselves as bastions of conservation, so the disappearing elephants represent a failure. When elephants die out in American zoos, they’ll likely be gone from American soil for good. Thanks to international and federal restrictions, no new African importing live elephants have been imported to the U.S. since 2003, when eleven orphaned elephants, which would otherwise have been killed to prevent overcrowding, were shipped from Swaziland. Zoos also generally support the ban on elephant imports: for many, conserving elephants in the wild is just as great a priority as educating visitors using captive elephants. While wild elephants don’t suffer the same fertility problems as captive ones, their populations are faltering from habitat loss and poaching.

So what’s the biological basis for captive elephants’ infertility? “It’s complicated,” says Natalia Prado-Oveido, a doctoral candidate at George Mason University who studies elephant endocrinology. Like humans, female elephants go through hormonal cycles. However, elephants’ cycles are four months long, instead of humans’ one-month menstrual cycles. At certain points in the cycle, female elephants will enter estrous, and become receptive to male elephants’ advances. But for some unknown reason, many captive elephants no longer undergo estrous cycling––and stopping the cycle means no more elephant babies.

Even wild elephants can stop cycling naturally for many reasons: when one female in a herd becomes pregnant, the others will “tamp down” their hormonal cycles for a while, so that the resulting elephant calves are more spaced out. “We do see periods when they stop and start [naturally],” says Prado-Oveido, “the problem is when they stop and don’t start up again. We call those the non-cyclers.”

The question now is why elephants in zoos are becoming non-cyclers. Prado-Oveido believes it’s at least partially explained by a condition called hyperprolactinemia––an excess of a protein called prolactin. When normal hormonal cycles associated with reproduction are “turned off” by too much prolactin, the ovaries no longer release eggs on schedule, and it becomes difficult or impossible for a woman (or female elephant) to become pregnant.

The problem with this theory is that not all non-cycling elephants have hyperprolactinemia: some elephants are infertile, but still have low prolactin levels. Recently, researchers have been testing human medications for hyperprolactinemia on elephants, but they haven’t had much success. This suggests that the problem lies elsewhere.

Prado-Oveido isn’t the only one working on the elephant fertility problem. New research, funded in large part by the Association of Zoos and Aquariums, points to something commonly associated with human infertility: fat. In captive elephants, high body fat strongly correlates with infertility. This is a huge problem, as about forty percent of captive elephants are overweight, despite healthy diets and encouragement to exercise.

It’s likely that there’s some link between hyperprolactinemia, the elephants’ weight, and their lack of regular hormonal cycles: in humans, the same conditions that can cause hyperprolactinemia can also cause weight gain. However, because researchers have only studied elephant endocrinology for about twenty years, the chain of cause and effect remains a mystery.

For now, researchers agree, the best thing that zoos can do for their elephants is to keep them as fit as possible, and to continue working with scientists to research the fertility problem. As Prado-Oveido says, “Saving endangered species has to be a concerted effort, or else it wouldn’t work.”

Infographic by Elizabeth Deatrick
Infographic by Elizabeth Deatrick

Birding in Boston – What Urban Birds Tell Us

This green space harbors more than just swans on boats––real birds use it too! Image credit: captain-tucker, Wikimedia Commons
This green space harbors more than just swans on boats––real birds use it too! Image credit: captain-tucker, Wikimedia Commons

By Elizabeth Deatrick
BU News Service

Birding in Boston is much more than just swan boats and the occasional pigeon––the city actually supports an enormous variety of bird species, and one scientist aims to find out why. Dr. Paige Warren, of the University of Massachusetts Amherst, has been studying urban birds and how and where they live. Recently, she has come to some surprising conclusions about what urban areas are best for birds––and what we can do to help both them, and ourselves.

In a recent lecture at Harvard’s Arnold Arboretum, Warren explained that the lives of urban birds are closely tied to social justice issues. The spread of lower-income neighborhoods in cities parallels declining bird populations––in part because poorer neighborhoods often have fewer full-grown trees, and therefore fewer attractive places for birds to live. Warren believes that, by studying how birds are attracted to urban green spaces, and how those green spaces can be improved and expanded, cities and towns can improve the lives of both people and birds.

Warren’s work focused on two cities: Phoenix, and Boston. Despite their radically different environments, the problems that have confronted birds in these two cities are similar: native habitats have been subsumed by lawns, houses, and other human-constructed landscapes.

Dr. Warren cites the invasive European Starling as an example of a generalist. Image credit: Matthew Briton, Wikimedia Commons
Dr. Warren cites the invasive European Starling as an example of a generalist. Image credit: Matthew Briton, Wikimedia Commons

But instead of disappearing from these environments, some birds––though not all––adapted quite well. These new “urban birds” were often generalists: they were not picky about what they ate. But there were limits: in Phoenix, Warren said, “The pigeons would just… stop at the desert [at the edge of the city]. They don’t go out there.”

Instead, more specialized birds took over around the edges, where green lawns were more scarce, and dry, xeriscaped yards that resembled the surrounding desert were more common. Warren acknowledges that this could be for a variety of reasons: either different kinds of birds are coming in from the desert, or xeriscaped yards are more likely to be owned by upper-class people, who can provide more varied kinds of food to their resident birds.

Thanks to a more temperate environment, Boston’s urban birds also prefer parks full of big trees with dense canopies, as well as large patches of undeveloped land. Warren cites the Emerald Necklace park system as an excellent urban bird habitat: it’s designed by and for humans, but it’s large, and has many old trees.

The Wood Pewee is a specialist bird that lives in the Boston area––it avoids very urban areas, preferring the cover of the trees. Image credit: Emily Willoughby, Wikimedia Commons. Sound credit: Jonathan Jongsma, Wikimedia Commons.
The Wood Pewee is a specialist bird that lives in the Boston area––it avoids very urban areas, preferring the cover of the trees. Image credit: Emily Willoughby, Wikimedia Commons.

Are large green spaces the only solution for encouraging birds in cities? Warren is adamant that even small green areas can make a difference. “We were, frankly, not expecting to find anything,” she said, but explained that small patches of greenery, such as tree-lined streets or tiny parks, do attract more birds than the surrounding city, even if they don’t increase the variety of bird species. “In general,” said Warren, “every 150 square meters of greenery gets you one more species.”

These small green spaces, scattered throughout the city, may have an impact on more than birds: Warren is sure that urban greening projects can help with social justice issues, such as urban revitalization––and she’s not the only one thinking that way. Cornell’s Celebrate Urban Birds project, in collaboration with many other organizations across the country, works with lower-income communities to get people excited about their neighborhoods’ potential––both for their avian and human residents. Like Warren, Celebrate Urban Birds sees the greening of urban spaces as a path towards better cities.

“Because a lot of our participants don’t have land, we have a list of plants that grow well in containers, and that attract birds,” says Karen Purcell, the project leader for Celebrate Urban Birds. “If there’s a good habitat for birds, and the birds are thriving, it’s good for people as well.”