Hi to all who have been following the University of Glasgow Tobago Expedition 2013. The expedition has now reached completion and we would like to say thank you once again to Zoological Society of London for their support and belief in the expedition. Additionally, thanks to all those who have been following our progress and reading our blogs. We cannot believe we are at the end – the time really has flown by. The past five weeks in the field have been eventful in all areas of our expedition research – whether sea turtle conservation, frog surveying or individual honours projects. This blog will attempt to describe the highlights of the past five weeks.
The 2013 Tobago Team
The Fishermen’s fetes around the villages of Tobago are now nearly over - the last of which is being held in Castara after we leave Tobago. The continual patrol efforts of the expedition have proved highly successful in limiting the number of poaching events that could have occurred during this period of celebration around the local villages. Due to sources of funding, N.E.S.T. members are now only patrolling beaches on Mondays, Wednesdays and Fridays as they are funded by an organisation largely focused on leatherbacks. The leatherback nesting season began to slow from the beginning of August and should finish by the end of this month. However, the Hawksbill nesting season can continue until October or November – albeit with only the occasional Hawksbill individual nesting on one of several North-East beaches in the later months. Therefore, the expedition has continued to monitor the two most popular beaches for nesting Hawksbills consistently every night. We can proudly report that again, since our last blog, no turtles have been poached from either Campbleton or Hermitage Bay. Our presence on the beach has been crucial for the protection of both adult and hatchling sea turtles, as eggs can also be poached. Furthermore, hatchlings experience predation from stray dogs, which can be deterred by the presence of humans.
Since our last blog, we have had over another 70 nesting’s (5 of which have been leatherbacks), over 20 tagging events (both new pairs and replacements) by expedition members, 3 nest relocations and over 50 hatchlings have been rescued during nest excavations. Indeed, one of these taggings included the placing of a tag on a turtle, which has travelled from Colombia as the expedition discovered due to the number on a pre-existing tag she possessed.
Nest excavations by expedition team members are now crucial in aiding the recovery of a slow-reproducing endangered species such as the Hawksbill sea turtle. When a nest begins to hatch, the first few hatchlings to stir stimulate the awakening of their siblings in the nest. Then, when the majority of the nest is awake in the nest chamber, the hatchlings utilise each other to break free by clamouring over one another to reach the top of the nest – effectively a ladder of hatchlings. Those who are most active break free from the nest and reach the sea within minutes of being on the beach surface. Unfortunately, some hatchlings will be left behind during these miraculous events, whether because they were weaker than their siblings in climbing to the top of the nest or because they had not fully awoken when the others emerged from the nest. Therefore, nest excavations enable the rescue and release of these individuals and provide them with a fighting chance to reach adulthood. Some hatchlings rescued from nests, also require additional stimulation from team members (by stroking the carapace and underbelly) before they are active enough to be released into the sea. Excavations therefore, maximise the hatching success of a nest where without them, many hatchlings would be trapped in the nest chamber and left to die.
Our nest excavations also enable us to identify the overall hatching success of a nest in relation to its location on the beach. For example, on Campbleton Bay and Hermitage Bay, many adults choose to nest in areas of the beach with lots of overhanging vegetation and undergrowth. Consequently, depending on the extent of this vegetation and associated wildlife, some nests have a large number of unhatched eggs whether due to bacterial or fungal infestation. Similarly, some nests can contain a number of infertile eggs or eggs which have stopped developing at different stages. Therefore, expedition team members open all unhatched eggs to identify the reason for this.
Our phase duration and thermoregulation (by way of egg temperature) data collection for University of Glasgow staff member Malcolm Kennedy has been highly successful. We have obtained enough data to provide an effective species comparison with Leatherback sea turtles, which a Glasgow University expedition in Trinidad is studying. The analysis and discussion of these findings should prove to be very exciting and reveal new aspects of marine turtle life history. We also spoke of parasitism of the eyes and cloaca in Hawksbills during our last blog. Interestingly, fewer individuals have been found with parasites in either area as we near the end of the nesting season. This could potentially be due to effective removal by expedition team members whilst collecting nesting event data. However, further analysis will be required to support this theory for lack of re-infection.
Close-up of juvenile
During our last blog, we were also excited to report the expected release of a recovered juvenile Hawksbill, following sickness from infection or blockage. This individual was found washed ashore by expedition team members on Campbleton Bay six weeks ago. The juvenile was brought back to Man O’War Bay cottages and given emergency treatment by expedition team members. Subsequent veterinary treatment followed in the two weeks after. The juvenile was given the all-clear to be released on Tuesday 16th July. Expedition team members and N.E.S.T. members headed round to Lover’s Bay (a quiet, secluded bay around the coast from Man O’War Bay) to witness the release by Grant Walker. However, all did not go as we hoped. The release showed great promise at first, as the juvenile swam away swiftly followed by snorkelling expedition team members monitoring its progress. Our snorkellers soon discovered though that the juvenile was unable to dive. Instead, bubbles would emerge from its carapace during attempted dives after which it would float back to the surface. Upon this discovery, Grant Walker and team members retrieved the juvenile and it was once again brought back to Man O’War Bay cottages. Contact with vets in Trinidad and Florida, in addition to research by expedition members, led to diagnosis of the juvenile with a buoyancy problem. This is particularly difficult to treat in sea turtles with treatment taking several months and no guarantee of success. Since this diagnosis, plans were made to transport the juvenile on Thursday 15th August to Trinidad where it will receive emergency treatment and x-ray, following which if the buoyancy problem cannot be treated, it will be transported to a sea turtle hospital in Florida. We can only hope for the best and remain positive that the juvenile will be successfully treated and released back into its natural environment.
Grant Walker releasing the juvenile
Bubbles emerging from juvenile
The weather in Tobago was very dry and hot until the second last week of the expedition when the local vegetation finally received a downpour of rain. Prior to this, conditions for frog reproduction were poor which made our surveying rather difficult, as individuals could not be located by calls. The heavy rainfall however, resolved this issue and also enabled team members to conduct driving transects around the North of Tobago where they recorded calls at the roadside throughout several areas in the north. This will allow the generation of a more accurate distribution map for all six of our target species in Tobago – all of which are vulnerable or endangered.
Despite the local destruction of transects mentioned in our last blog, P. charlottevillensis and P. urichi have been sighted and heard calling consistently by team members whilst surveying. However, P.turpinorum continued to escape detection due to its elusive call. We are now extremely doubtful that P turpinorum does in fact still exist on Tobago. More specific twilight searches by expedition team members did not yield any results therefore the outlook for its population status is grim. Several individuals collected by team members whilst surveying had the potential to be a P. turpinorum. Yet, after using identification keys, none were actually a member of this species. Recommendations will be made to frog experts to conduct specialised searches for this particular species. It is possible that P. turpinorum was never a new species and individuals classified as members of this species were in fact juveniles of other species of the genus Pristimantis. Furthermore, P. charlottevillensis is experiencing diversification with the appearance of many different colour morphs. This adds further to the confusion surrounding P. turpinorum as this species may actually be a different colour morph of P. charlottevillensis. Alternatively, P.turpinorum individuals collected in the past may have been the last surviving members of a critically endangered species, after which the population could no longer reproduce and sustain itself subsequently collapsing. Again, further research will be required to determine this – potentially with the usage of DNA sequencing.
During the 7th week of the expedition, we had a visit from our expedition staff supervisor, University of Glasgow Honorary Professor Roger Downie, who had been visiting our sister expedition in Trinidad. Roger was extremely pleased with the work the expedition has been doing during his stay and was particularly impressed with each student conducting an honours dissertation. He made several recommendations to each of them, which have subsequently improved the quality of their data collection. Steven Duncan has been investigating the population, distribution and ecology of Mannophryne olmonae, Flectonotus fitzgeraldi and Hyalinobatrachium orientale for his honours project. This project was also managed by Steven on the 2012 expedition. He continues to express concern for M. olmonae and F. fitzgeraldi as there have been few sightings by expedition team members in comparison to last year. He believes this may be due to lack of rainfall this year in comparison with 2012, resulting in many breeding pools for M. olmonae drying out. The outlook is better for H. orientale, which has been sighted regularly and heard frequently. However, sightings have been less frequent than last year. Habitat degradation, in addition to the lack of rainfall, is a particular suspect for population changes in sites monitored since 2012. Steven has also observed irregularities with the Main Ridge population of glass frogs. This population is particularly small and appears to exist without the presence of broad leaves (such as Heliconia). Steven has not encountered any information regarding this throughout his research on glass frogs and thus believes Main Ridge may be separate population. It could have resulted from the destruction of broad leafed vegetation by leaf cutter ants at Main Ridge causing glass frog individuals to use palm leaves for laying their egg clutches. Steven’s analysis of his findings will likely illuminate several environmental factors, which may affect the distribution and presence of these three species.
Chris Pollock has been conducting his dissertation research on the parental behaviour of the male glass frog (H. orientale). Chris’s manipulative experiment - where male glass frogs observed with egg clutches are removed whilst maintaining control clutches where the male is allowed to continue to care for his young - have been very revealing. Thus far, any clutches where the male was removed, have become desiccated and/or predated. On Tuesday 16th July, Chris and team member Jade went on a late night observational trip, where they witnessed glass frogs mating and the act of laying by the female glass frog. Furthermore, they also observed male defensive behaviour over egg clutches against a mating pair of glass frogs nearby. However, the mating male saw this behaviour as potential theft of his mating partner and consequently, challenged the male with eggs. An odd stand-off ensued where neither male understood the other’s actions. This is but one example of novel behaviour in amphibians, which we believe has been largely unexplored. While he has yet to start analysis and discussion for his dissertation, at present, Chris believes the male glass frog is solely responsible for the survival and success of his offspring. Parental care is particularly necessary during the early development of egg clutches. Chris has observed egg clutches which have been abandoned half-way through their development but may yet still survive and reach adulthood. However, clutches abandoned during the first few days of development have no chance of survival. This year has been especially dry despite our fieldwork being conducted in the wet season in Tobago. Thus, amphibian survival is further threatened and behaviours such as parental care are a crucial evolutionary adaptation to increase survival.
Glass frog guarding egg clutch
Next, Melissa Craig has been researching ectoparasites of the invasive Cane toad (Bufo marinus) – first introduced to Tobago last century to control sugar cane pests. Several years ago, a similar project was conducted by a Trinidad expedition team member who found tick load correlated with habitat type but sex and size were unrelated. Wounds associated with previous tick attachment were common and increased chance of secondary infection by other parasites. After sampling several different sites in the North-East of Tobago, Melissa has found tick infection to be extremely prevalent amongst members of Tobago’s cane toad population. She suspects, as was found in Trinidad, that habitat type does indeed affect infection rate of toads with infection rate being much higher in areas of disturbed habitat. Individuals in disturbed areas such as Hermitage Bay, come into contact with much human-induced pollution such as fishing equipment, which also attracts pest species e.g. rats. Thus habitat type may correlate with individuals found with scars and lost limbs – indications of reduced health status. Habitat type and health status may then correlate with rate of tick infection in sampled individuals. Notably, she has observed cane toads appear to preferentially utilise disturbed habitat over natural habitat although they do continue to persist in undisturbed areas of rainforest.
One of the team members with a hawksbill turtle
Level 4 MA Geography student, Mairi Hilton has been conducting her project on the effect of storm events in Tobago on the profile of a key beach for nesting Hawksbill sea turtles - Campbleton Bay. Using the data gathered by the expedition and the local NGO N.E.S.T. on this species, she is examining the effect of beach profile on the number of nest relocations which have to be conducted and the variation in return time between nesting by Hawksbill sea turtles. Females of this species usually lay 3 or 4 clutches during a season in which they are reproductively active. The time between clutches can vary between 11 and 20 days. At present, without analysis, she suspects lunar cycle and tide elevation are more likely to be responsible for variation in return time of Hawksbill individuals between laying clutches. These in contrast with effect of storm events, which she first anticipated would affect return time. Furthermore, she too expresses concern for this species due to lack of rainfall in 2013. The dry weather has enabled a large number of turtles to nest on the riverbank where nests will inevitably be washed away should extreme rainfall occur in subsequent weeks. Nest relocations by expedition team members can alleviate this problem but Campbleton is such a dynamic beach that we cannot predict how the profile of the beach will change following extreme weather. Therefore, several nests will still be lost should the river banking change completely. In addition, the grain size of the sand is affected by the weather, which could in turn impact nest success.
Kirsty Earle and fish trap
Shortly after our last update, Marine Biology Honours student Kirsty Earle finally had success with the traps she was attempting to use to sample fish around different streams in North Tobago. She has been conducting her honours dissertation as an investigation into size variation amongst members of a fish species in Tobago, known as Gobiomorus dormitor. She will be providing a habitat comparison for this particular species where size and abundance may be affected by environmental factors. In addition to those conducting honours projects on the expedition, Giovanni Bianco has been investigating unusual behaviour by a species of bird commonly known as the Motmot. Mike Rutherford, from the University of West Indies, observed that select individuals use rocks as anvils to break open mollusc shells. Exactly when, or how many individuals display this behaviour though, is unknown so Giovanni has been conducting an observational study of individuals at Pirates Bay. Wonderfully, he has obtained video footage of an individual displaying this behaviour, which will serve not only as scientific proof but also as a tool for analysis of the intricacies involved in this behaviour.
Joe and Giovanni measuring a morning turtle
The past ten weeks have been a unique and unforgettable experience for each member of the 2013 Tobago team. They have gained fieldwork experience in two diverse areas of zoology, honours students have learnt how to conduct a research project and additionally, all have experienced a new culture, gained world experience and a new perspective with regards to conservation. We are so grateful to all those who have funded us and would like to express our heartfelt thanks to ZSL for choosing to support our expedition. Without their support and support from other funding bodies, we would have been unable to come to Tobago and achieve all that we have. We truly feel our presence on this island has made a difference and will impact future conservation of Tobago’s wildlife. Many islands such as Tobago, have so much to offer to science due to the high biodiversity within areas of largely untouched, preserved rainforest. However, without conservation efforts from groups like those from University of Glasgow and local people who have chosen to take a stand and reject traditional cultural practices, such as those who are members of NGO N.E.S.T., the outlook is bleak for Tobago’s wildlife. Indeed, some of it could be gone within the next decade or as we suspect with P. turpinorum, is already gone. The expedition will continue to run to Tobago next year, which we believe will be every bit as successful as this year was. We hope ZSL is anticipating our final report and hope all those who have been following these blogs are proud of what the young people involved on this expedition have achieved.
Lynsey Harper (Co-leader)
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