Invasion of the bulbuls: Houston team studies new invasive species

March 24, 2014

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.

Authored By Vincent Covatto

Vincent is the Copywriter at HMNS.

7 responses to “Invasion of the bulbuls: Houston team studies new invasive species”

  1. Steve Hurd says:

    These Red Vented Bulbils have been here in my Woodland Heights neighborhood
    for a number of years it seems. I saw them in my own yard about 5 years ago.
    They are not nesting here on my property, but are frequent visitors, eating berries
    and insects it seems. They seem to eat much of the same stuff as mockingbirds.
    They don’t seem to be aggressive to me, -or at least not as much as the
    mockingbirds, who usually watch them carefully when in their territory. They feed
    much like warblers do by hanging upside down and looking under every leaf and
    stem. We’ll see if they become a pest or not in the future. They seem to be tolerant,
    or at least indifferent to people.

  2. Denise Crouch says:

    I am a teacher at Helms Elementary. We spotted a couple of pairs of these birds out by our Wetlands area. Swing by our school for a better look.

  3. Julie Rhoades says:

    There is a pair regularly visiting the tree outside my office window in the West Alabama Upper Kirby River Oaks area. They eat berries until run off by the nesting robins. I have not seen any aggressive behavior by the bulbuls.

  4. Jesse sifuentes says:

    Bulbul sighting. In the AM. At Smither park. In a mulberry tree. Last spring . Also last week

  5. Nina Garcia says:

    I just saw these birds only two by the Spanish Flowers Mexican Restaurant in the Houston Heights and I was like I had not seen them before and I looked in my Audubon Bird App to see what it was and I couldn’t find the bird on the app so I gave a description of the bird on Google till some good results popped up and I found the bird’s name and some pictures of it, So I basically saw a new bird I had never seen before.

  6. Alex Morales says:

    I have seen quite a lot of these amazing little birds in my neighborhood in EaDo. Last year there was a pair roosting nightly on one of my carambola trees. I have seen at least more than a dozen pair flying around.

  7. Corinne says:

    I have seen a small group of these birds several times. Yesterday, I saw 4-5 high in the trees near White Oak Bayou, near i-10 and Heights blvd. There was a 1-2 males, 1-2 females and a juvenile. They seemed to be passing through or resting, not foraging, at the time, but I’ve seen them at my bird bath in the past.

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