Invasion of the bulbuls: Houston team studies new invasive species

Editor’s note: This blog post is a summation of “Ecology, Behavior, and Reproduction of an Introduced Population of Red-vented Bulbuls (Pycnontus cafer) in Houston, Texas,” written by HMNS Curator of Vertebrate Zoology Daniel M. Brooks and published in The Wilson Journal of Ornithology.

 

Invasive species are (unfortunately) nothing new to Texas. Defined as an “introduced species that adversely affect the habitats and bioregions they invade economically, environmentally, and/or ecologically,” invasive species (aka invasive exotics or exotics) can have wide-ranging negative impacts on regions.

Species such as giant salvinia, feral hogs, zebra mussels and nutria constitute invasive species currently wreaking havoc on Texas wildlife, having decimated food sources and changing ecological dynamics, and even threatening other species’ survival in their environmental niches. It’s for this reason that many scientists have begun to study introduced species and their behaviors before they decimate their new habitats.

In light of this, Brooks initiated the Texas Invasive Bird Project in June 2008, a citizen-science study targeting six avian species invading the state. One of these is the red-vented bulbul (Pycnonotus cafer). This species was previously unstudied in Houston.

The red-vented bulbul is native to Pakistan, India, and Sri Lanka, but has become a well-established invasive species in parts of the Middle East, various tropical Pacific islands … and Houston. In its native and introduced regions, it can be found in a variety of habitats, including urban gardens. In the Houston study, we aimed to determine the ecology, behavior and reproduction of the bulbul through a questionnaire made available at birdwatching clubs, annual birdwatching festivals and circulated on internet list serves. Most of the respondents were either birdwatchers familiar with bulbuls or horticulturalists who maintain diverse gardens.

The results determined that the most frequent activities for the birds included foraging, perching or resting and calling. Ninety-six percent of the reports described residential suburbs as the primary habitat of the birds, with the highest concentrations being found in the Heights neighborhood. In these areas, they were observed perching on 35 species of plants, and feeding on 20. Forty-three percent of the plants they perched on are native to Texas, while only five of the 20 plants they fed on are native to Texas. The most common plants used for perching were also exotic plants (bamboo, crepe myrtle, fig and tallow), which are all found in the native range of the bulbul.

They are generally non-migratory birds. But the largest flocks appear at regular intervals between August and September, and then again from December through January, traveling in flocks of 12 to 22 birds. This matches their patterns in other regions, while their numbers are much smaller in Houston (with gatherings of 20 to 100 birds within their native range).

Ultimately, it seems that bulbuls are not currently a threat to Houston, but they should continue to be closely monitored. While they pose no current negative economic threat as they do in Pacific islands (such as Oahu, where they’ve decimated tropical plant crops), it seems that their largest potential threat in Houston remains through seed dispersal. In this area, they have great potential to disperse noxious weedy seeds, as they have done in Fiji with spiked pepper, guava, and prickly night-shade.

In the meantime, the birds seem to be enjoying their niche in previously untapped resources of other exotic plants brought to Houston and used in gardens, which other birds have not used with great regularity to eat or perch in. However, as the population continues to increase and spread through the region, we will have to monitor any changes that may occur which could negatively impact native species.

Tales from Tanzania: Oh, the things you’ll find in a caldera

On the next leg of our trip, we visited the Ngorongoro Conservation Area.

NgorongoroNow, you may ask, “Nicole, your last adventure was in a national park, and this is a conservation area — what’s the difference?” And I’d answer that a conservation area has people living on it, whereas in a national park, no permanent settlements are allowed. The Maasi people live in the Ngorongoro Conservation Area with their cattle full time. They have been allowed this exception since they do not hunt. According to their traditional customs, they are only allowed to eat cow, goat and sheep so the wild animals in the crater have nothing to fear from them.

The Ngorongoro Conservation Area is especially interesting, as it contains the largest unbroken caldera in the world. It was created by a volcano, which has now collapsed. Before it collapsed, the volcano would have been much, much higher than Kilimanjaro.

The formation of a caldera

The crater has given rise to a variety of ecosystems due to its geography and sheer size. Moisture is pushed in from the ocean in the east, but it gets caught at the rim of the crater. The outside eastern edge of the crater, therefore, is home to a thick highland forest full of tropical birds. The west side of the crater only gets rain in the rainy season and most of the time looks something like dry west Texas.

Interestingly, the crater is responsible for most of what we have seen and what we will be seeing on this trip. The eastern edge of the crater is so dense that natural springs flow into Lake Manyara rather than the crater, keeping it green and providing a source of water for animals.

Looking to the west, when the volcano erupted 2.5 million years ago, the wind blew the volcanic ash to the Serengeti, which caused hard-packed earth that only the acacia can penetrate.

Later in the evening, we were able to talk to crater naturalist, Yotham, at our hotel. He was very surprised to see several of our pictures (we always knew we were looking at something awesome if one of the driver guides took out a cell phone to take a picture).

In particular, Yotham was surprised to see our shots of the Little Bee Eater, as they usually don’t come into the crater. Instead, they live in the highland forests on the outside western edge.

DSCN1517DSCN1205As we continued to go through our shots, he indicated that we had, in fact, had a very, very good day of observations.

Here are some of the highlights: 

Hyena kill: We arrived right after the wildebeest was taken down. Just out of screen are several other hyenas and 20 or so vultures waiting for their turn at the carcass. The eating hyena kept dragging the carcass away so it could eat without feeling crowded.

DSCN1604Ostrich: So, I learned something new today. When you see a male ostrich with a bright pink neck, it is feeling frisky. A male ostrich with a white or gray neck is not currently interested. Female ostriches are very beautiful but very differently colored than the male ostriches.

DSCN2036DSCN2048Serval: This picture is a bit miraculous. The serval is normally a nocturnal animal, so it was amazing to see it out during the day. AND THEN IT STARTED HUNTING. AND IT WAS AWESOME.

DSCN1957

Na na na na na na na … BATS, man!

For bats being amazing examples of evolutionary resilience and fascinating, intelligent creatures with complex, long lives that perform invaluable ecological roles, we humans don’t seem to appreciate them very much. They’ve had a bad rep in cultures around the world due to their association with the night for millennia, but what’s this based on, really? Fear of the dark? Jealousy? Our imaginations — which can make almost anything out to be our “enemy”?

Like many other things deeply ingrained in our social consciousness, these feelings have been added into our speech patterns. We often use an association with bats to point out odd or unfavorable behavior.

Take for instance:

“Without my glasses, I’m blind as a bat.”

“From his erratic behavior, we were sure he had bats in the belfry.”

“She ran away like a bat out of hell.”

Well, how about this:

“Without my glasses, I’m blind as a bat. No, really I’m fine — I don’t need them. My sense of smell and hearing are better than using sight anyway. Oh, and I’ve been around for 50 million years, so I’m pretty sure I know the lay of the land anyway, so NBD. By the way, I provide an invaluable service to humankind by eating the insects which seem to cause them so much trouble.”

OK, a bit wordy, but you get the idea – bats are freakin’ awesome. They’re the only mammal that legitimately flies – having developed wings out of what used to be hands (look at their skeleton and you’ll see how crazy this is; it would be like having webbed fingers that go the length of your body!).

And they live nearly everywhere on earth, except for some small, isolated islands. Now that’s what I call evolutionarily resilient.

Bats are native to the orange areas on the map. (Which is pretty much everywhere.)

In spite of all this awesomeness, bats in America are under threat from a new disease called White-Nose Syndrome. This disease is caused by a fungus which is taking hold in caves along the entire northeast corridor. It infects bats while they’re hibernating, so their bodies have essentially shut down and can’t fight it. The fungus causes their flesh to deteriorate as the spores take hold and suck the water and nutrients out of the bat. This causes them to wake up and search for food (which they can’t find, because it’s winter), wasting the rest of their fat reserves and leading to starvation.

The fungus appeared in New York in 2007 and has since killed millions of bats who seem to have little to no way to fight it. It came to New York from Europe; however, the bats across the pond don’t seem to mind nearly as much as American bats. This leads some to believe that they’ve evolved to be resistant to it (think Black Plague resistance in European populations — or lack thereof when smallpox came to America).

White Nose Syndrome by found county

But that’s not to say all hope is lost! Scientists across the country are performing research to learn more about the fungus — mapping where it’s been found, how it takes hold, and performing experiments to prevent the onset of the disease.

(You can learn more here, here, here, here, and here.)

But one of the best ways to help save the bats is having a well educated population that’s invested in the little furry flying guys. Lucky for YOU, there’s an exhibit at HMNS Sugar Land opening on Sat., Jan. 18 all about bats! Come to Masters of the Night: The True Story of Bats and learn all about these amazing creatures (and, come spring, you can check them out in Houston under the Waugh St. Bridge).

 

Nota bene: Baby bats are super adorable. I hereby submit that they should become part of the never-ending flood of baby animal pictures shared around on social media as to better their public perception.

Don’t believe me? Just check these out.

One in a million: Last-minute Bolivian bat netting yields a brand new big-eared bat

Notwithstanding the horrible tragedy of the Columbine (Colorado) incident, April 1999 was by far one of the most surreal experiences of my life. Not even a week prior to leaving, I was preparing to give final exams for courses I was teaching at the time. I was about halfway through creating an exam when I received a phone call from a former student, who sounded a bit short-winded and stressed out.

As I asked him to slow down, he explained that the environmental consulting company he worked for was between a rock and a hard place, and had to redo a series of environmental impact statements — this time using biologists experienced in the area. I immediately dismissed myself as a candidate, explaining that I had final exams to give soon, and then I was off to my site in the Peruvian Amazon where I would lead a natural history tour, followed by field work (my usual grind this time of year).

It was at this point during the conversation that some things were pointed out to me that made it difficult to say no — namely the incredible opportunity to work in one of the least explored areas in the neotropics, my specialty region of focus.

This map depicts the country of Bolivia with Chiquitano forest (light shading) extending east into Brazil, as well as Cerrado (dark shading). The dots represent the general region we worked in (map produced by K. Koy).

This map depicts the country of Bolivia with Chiquitano forest (light shading) extending east into Brazil, as well as Cerrado forest (dark shading). The dots represent the general region we worked in. (Map produced by K. Koy.)

Less than 50 hours after that life-changing phone call, I had convinced co-workers to give my finals and cover the tour in Peru for me, left my keys with someone to house-sit, and was on the red-eye to Santa Cruz, Bolivia! Also during that time, I quickly helped hire a science staff of about 30 biologists (mostly Bolivian, some ex-pats, and a couple of Argentines) to undertake a Rapid Ecological Assessment (REA) of the eastern Bolivian panhandle.

Things were very busy indeed.

The politics of the situation were gruesome, and I was ecstatic when I was finally granted permission to just begin getting people into the field to do our work. A botanist from Spain was responsible for forestry, plant community and hydrology crews, while I worked with the vertebrate zoology crews (birds, fish, herps, two mammal crews). Wanting to become involved “on the ground,” I joined up with the mammal crew and we got ourselves situated at the base camp, Las Conchas.

Julieta Vargas and Hugo Aranibar, young mammalogists from the Colección Boliviana de Fauna (National Museum in La Paz), José Manuel Rojas (also a mammalogist) from the Museo de Historia Natural Noel Kempff Mercado (in Santa Cruz), a couple of others, and myself comprised the mammal teams. Although they were allowed to leave a full day before me (via four-wheel drive vehicles) while I was stuck in administrative hell in Santa Cruz — my helicopter ride to Las Conchas more than a day later actually landed me at the remote field site half a day before their arrival.

After resting up the first night, we were ready to hit the field! The only problem was inclement weather that prevented helicopter flight to some of our target areas. After several hours we became bored with no entertainment, save a deck of cards. So we decided to inventory the region around the base camp.

On the evening of April 17, Julieta, Hugo and José Manuel snuck off to do some bat netting. Any seasoned bat netter knows that nets need to be monumented in a long continuous linear run, sometimes with a T-head on the end, but always surrounding a resource (e.g., a fruiting tree, a light luring in many insects, over water, etc).

Well, by the time I was able to cut loose of my meeting and catch up with them, I found that they erected only a single mist net in the middle of a small patch of savannah surrounded by patches of Cerrado forest. To make things even more dismal, it was drizzling and tiny beads of rain clung to the otherwise virtually invisible net. Another thing any seasoned bat netter can tell you is that netting in the rain is a waste of time, because the bats can detect the rain droplets on the net and will thus avoid it.

So I feared our chances of netting any bats that evening were maybe one in a million? Of course I didn’t have the heart to tell Hugo and the others that the netting was gone about all wrong — they were SO EXCITED; how could I possibly rain on their parade?

Nothing short of miraculous, we actually caught a (i.e., ONE) bat that evening. We knew it was a specimen of the genus Micronycteris (big-eared bat), but beyond that I was uncertain — it was very late, very dark, and we were very tired. We collected it and decided to key it out in the morning once recharged.

Photo of holotype of M. yatesi by A. Muñoz, provided by L. Siles.

Photo of holotype of M. yatesi by A. Muñoz, provided by L. Siles.

In the morning and through the rest of the trip, I pored through dichotomous keys, but was unable to assign our little bat to any known species previously reported for the region. Could this be something new? After convincing myself there was no way in hell we’d net a bat that evening, if the ONE that was netted turned out to be something new … that would be pretty cool. I felt a little like I was witnessing the scene in the Peanuts Christmas special when Charlie Brown buys the measly little tree that gives out and all but dies. Then his buddies come and pour some TLC into the tree and make it pretty cool after all.

After returning to the U.S., I went to visit Nancy Simmons, a Micronycteris specialist, at the American Museum of Natural History to see if she was able to designate the specimen to species level. Simmons suggested it likely represented a new species most closely allied to the Micronycteris sanborni group.

So I put out the word to other bat scientists working in Bolivia to be on the lookout for this unique little bat. After several years, we were finally able to find someone else who netted some of the unique little bats, Liz Siles.

Many years and much work later, we were finally able to describe the new species fully in a recent article in the Journal of Mammalogy. After some discussion, we decided to name this species “Yates’ big-eared bat (Micronycteris yatesi),” after our late colleague Terry Yates of the University of New Mexico and the National Science Foundation.

The etymology reads, “This species is named in honor of Terry Lamon Yates (1950–2007) for his pivotal contributions to the knowledge of Bolivian mammals, training Bolivian biologists, and starting collaborations that strengthened mammalian research and shaped current science and field biology in Bolivia.”

Since the big-eared bat find in Bolivia, it is really spectacular to see how far the main players have come. Julieta, Hugo and José Manuel were fairly young and green mammalogists at the time; today they have their own career trajectories. Julieta ultimately became Curator of Mammals at the National Museum in La Paz. Hugo went on to direct a program for the highly endangered Wattled Curassow (Crax globulsa) in Bolivia (read here for an account on this rare species). And my dear hermano boliviano José Manuel became increasingly involved in human sustainable living, now working on these projects in rural Bolivia.

As for myself, it was overwhelming how much I was able to accomplish in my career as a result of this trip. From the REA, I was able to describe two new species of mammals (a rice rat and the bat), got three wonderful mammalogy grad students working in Bolivia, and published some great manuscripts on the birds and mammals of this unique region.

Sometimes life taps you on the shoulder to take a chance. Even though I wasn’t able to administer my own finals or go to my field site in Peru that spring, this one in a million chance of a lifetime was irreplaceable – VERY glad I took the chance to stray off the beaten path.