Birding Notes from Ambergris Caye

On the last full day of our trip to Ambergris Caye, I had the chance to go on a birding excursion to a Mayan ruin site outside the town with Professor Paul Patev and Belize fellow Alyssa Ferrell. Despite the blazing mid-day heat, we were able to observe several exciting species. As sometimes occurs when birding, some of the most exciting species we saw were not at the destination itself. On the way to the ruins, we made a stop at a sandfill that looked promisingly “birdy”. Sure enough, in addition to several other species, we saw the striking White Ibis (Eudocimus albus) and the undeniably odd Black-necked Stilt (Himantopus mexicanus) in the brush and standing water along the side of the road. Upon arriving at the ruins, we had looks at several woodpeckers, orioles and flycatchers. Although the birds seemed unperturbed, I found that even under the shade of the trees, the noonday sun was uncomfortably hot. Wanting to sit down for a minute, I walked over to a comfortable looking tree bough low to the ground, only to be greeted by a sign hanging from the branch with the label “poisonwood”. After a short search on Google, I believe this was probably Metopium brownie, commonly known as Black Poisonwood, which contains the same irritating urushiol found in the poison ivy of Massachusetts.  As we were exiting the area, we were lucky to get long, close up looks at a Tri-colored Heron, which was standing on the boardwalk just ahead of us. By its plumage and slightly confused behavior, I’m fairly confident this was a juvenile bird. Young birds will often allow for closer approach than adult birds. Due to the agitated behavior of a nearby pair of stilts, I believe they nest in that same area as the herons there.

In addition to listing birds, I noticed two aspects to birding on Ambergris Caye that surprised me. First, Eurasian Collared Doves (Streptopelia decaocto) seem to be established on the island. This species is not even listed in my guidebook to birds found in Belize, so I’m guessing it exists only in isolated patches or its presence is a very recent occurrence. It is also possible all the birds I saw were escapees and the doves are not currently breeding on the island, but this seems unlikely to me. I do not know what the potential implications of this new species are for the many native avian species of San Pedro. My second observation was the curious lack of gulls along the shoreline, especially given the fact that fishermen frequently clean fish in the shallow water along the beach. I suspect the fishermen do this, in part, to give tourists a chance to interact with the incredible Southern Stingrays (Dasyatis americana) that will swim right over people’s feet to get pieces of fish. However, I would expect gulls to similarly take advantage of this handout given the usual scavenging behavior of many gull species. The abundant Magnificent Frigatebirds (Fregata magnificens) certainly seemed to have no hesitation in diving for nearby scraps. I began to wonder if these large, opportunistic Frigatebirds might outcompete gulls for resources on San Pedro, as they seem to behave in a similar manner to the latter.

I left San Pedro marveling at the species that can be seen both above and below the surface of the water. I naturally hope to return someday! After all, I still need Roseate Spoonbill on my life list…    

 

Comparing Invertebrate Counts

The invertebrate creatures that life on the coral reefs are in integral part of the vast and complicated ecosystem that has been referred to as the rainforest of the oceans. There is much about these ecosystems that we do not understand, and compiled with the complicated effects of human impact reefs makes it even more difficult to understand. However, after compiling years of data and the results inferred, it has been determined that there are key indicator species that can be used to determine the health of a reef. Almost as one would do with a canary in a mine shaft.

The species that have been determined by Reef Check to be indicator organisms based on economic (harvested for the aquarium trade) and ecological (balancing the algal growth) value are;
1) Banded coral shrimp (Stenopus hispidus)
2) Diadema urchins
3) Pencil urchin (Eucidras spp.)
4) Collector urchin/sea egg (Tripneustes sp.)
5) Triton (Charonia variegta)
6) Flamingo tongue (Cyphoma gibbosum)
7) Georgonian (sea fan, sea whip)
8) Lobster (Palinuridea)

While in our reef ecology class we reviewed and studied an article that studied and almost certainly concluded that the diadema (black spine) urchin was not only integral, but perhaps the most important, or key stone, invertebrate species within the coral reef ecosystem. Following a mass die out of diadema (aprox 95%) in 1984, the increase of alga was almost instantaneous. However, since the return of the diadema in recent years (since the mid 90s) they greatly reduced microalgal (from >60% to <5%) which in turn increased coral growth. The study was conducted throughout the Caribbean, but the discovery of the impact of the diadema was a place called Dairy Bull, in Jamaica. It was here that there as actually been an increase in coral cover in the past two decades (in vast contrary to the rest of the Caribbean), almost 100% more living coral and 90% less algal cover then it did in 1995. This coral growth is occurring even while overfishing is still a problem. This phase shift in coral growth  appears to always be preceded by the recovering and increased population of the diadema urchin.
Source:
http://www.int-res.com/articles/meps_oa/m403p091.pdf

On the first dive located at, Buena Vista, we discovered invertebrate species in the low single digits only. This had also been a trend in most of the dive sites we had been to prior to our Reef Check dives. In addition to the lack of invertebrates, their was large amounts of coral disease and bleaching. Their was a large amount of algal proliferation, as well as a great over abundance of georgonians. The site just looked sick.

In contrary, the second dive site, Coral gardens, looked radically healthier. The amount of diadima urchins was around 50 and pencil urchins was even more then that. Also, reef urchins, which are not counted by Reef Check would have easily surpassed 200 if they had been counted. There were more flamingo tongues, and even two collector urchins, the georgonian count was also much lower. The coral substrate itself was vastly more abundant and disease and bleaching was far less prevalent. Also, there was significantly less algal proliferation. Both sites are legally allowed to be fished and the species discovered at each site were about even.

With out conducting a purely scientific study we can not make any fact based conclusions. However, from the data we gathered and what we were able to see just from being there supports the findings of the article we studied in class and the study it was based on. The diadema urchins, and other herbivores are indeed a keystone species. They are integral to the promotion of of healthy coral and increased coral growth. In addition to this, what we observed at another site, Hol Chan, also supports the article. While not a Reef Check site (so we did not study, just notice and observe), it is protected from fishing, which means far greater number of fish species. However the overall health of the site was less the that of Coral Gardens, and in parallel to that the amount of diadema we noticed was far less.

The coral reefs are an incredibly complex biosphere, and the more we study the more we learn. Reef Check, and the observations we make while conducting it, is an invaluable asset into this learning process. Just seeing that the two locations we studied were so different and the species we found in each site is an enormous help. The fact that what we found supports conclusions by other scientific data is large step forward in the understanding of healthy reefs. Hopefully, with time , the damage that has been done to the reefs can be stopped and the health of these underwater biosphere can be returned to their natural unparalleled state of beauty.

 

 

What we are actually doing

A brief overview of what we are doing and why we are here, with out getting into too much detail or getting too complicated.

The coral reefs around the world are dying, a variety of reasons contribute to this tragic fact; over fishing, climate change, water pollutants, and degradation of terrestrial habitats are thought to be some of the causes. However, because of the sheer expanse of the coral reefs its very difficult to pinpoint many of the whys and hows. Also, these different causes have a varying effect on the complicated ecosystem of the reefs. Regardless of this, the more data we have the more solid conclusions we can come to. That is were Reef Check, and people like us come in.

Because of the expanse of the coral reefs, the job of surveying and studying them can not be left to scientists alone. Reef Check was created to establish standard parameters and methods in which citizen scientists could work with and under qualified individuals to gather the necessary data around the world. Some of the goals of Reef Check are to educate the public about the reef crisis, create a global network of volunteers, scientifically investigate the coral reef ecosystem, and to stimulate the local community into taking taking action to protect their reefs.

The first thing we do is lay out a 100m transect line along the chosen reef that meets the required criteria. This is done at two depths, one of 3m and one of 10m. Then using that line we collect four types of data:
1) A description of each reef site based on over 30 measures of environmental and socioeconomic conditions and rating of human impact.
2) A measure of the percentage of the seabed covered by different substrate types, including live and dead coral, along four 20m sections of a 100m shallow reef transect.
3) Invertebrate counts over four 20m x 5m belts along the transect.
4) Fish counts, up to 5m above the same belt.

We took the reef ecology course to learn about the reefs and their ecosystems, as well as their global impact and importance. We all had to be SCUBA certified , as well as spend time learning the diving skills required to collect the data. Then it was our job, broken up into assigned teams, to collect and record the data under these parameters.