Introduction

Personal research interests have been combined with teaching both under- and post-graduate students on expeditions to Trinidad &

Tobago most years since 1989. Data-gathering and execution have benefited from association with the Exploration Society of the

University of Glasgow (see Downie, et al., 2017). The Percy Sladen Memorial Fund has been a particularly valuable source of small

grants that can be used for equipment purchase for expedition projects. Here we present information from three different research

themes.

Frogs, turtles and insects in Trinidad & Tobago

Hunterian Museum

(Zoology)

.

J. Roger Downie1

E Geoffrey Hancock2

Malcolm Kennedy1

1. Institute of Biodiversity, Animal Health and Comparative Medicine

2. Hunterian Museum, University of Glasgow, G12 8QQ, Scotland, UK

Acknowledgements

We are pleased to acknowledge the support of the Percy

Sladen Memorial Fund over a number of years. A considerable

number of colleagues and students, past and present, have

helped with their hands and brains during the same period

Neotropical frog reproductive ecology

An award in 2010 allowed the purchase of two

accurate 0.001g resolution balances, and another

in 2015 provided a set of temperature/humidity

dataloggers. Although spring balances are useful

in the field for weighing adult frogs, they do not

provide enough resolution to weigh tadpoles. The

availability of the balances has allowed us to

carry out several studies on tadpole development

and competition, such as Downie et al.’s (2013)

report on leaf nests and egg hatching in the tree-

frog Phyllomedusa trinitatis. Egg masses are

folded in leaves overhanging forest pools.

Eggless jelly capsules scattered amongst the

eggs, and jelly plugs at the nest top and bottom

provide a water supply that allows development

to a late stage when the tadpoles tend to hatch

then fall from the base of the nest, several

hundred over a fairly short time, into the water

below.

The temperature/humidity loggers have been

used so far to measure the microclimate in which

Tobago glass frogs Hyalinobatrachium orientale

develop. These are laid as a flat clump, each egg

surrounded by jelly, adhering to the lower surface

of a leaf, often of a Heliconia plant, that

overhangs a stream. Unlike Phyllomedusa egg

masses, those of glass frogs are open to the

atmosphere. The eggs take about ten days to

reach hatching stage, when the tadpoles fall into

the stream below. As part of a study into the costs

and benefits of using the underside of the leaf

(other genera of glass frogs utilise the upper

surface), we attached the loggers to both sides: so

far, surprisingly perhaps, the temperature and

humidity measurements we obtained differ little

between the two surfaces, except during heavy

rainfall. The results will form part of a series of

papers in progress on glass frog reproductive

ecology (Nokhbatolfoghahai et al., 2015). JRD

ReferencesBarabás, S.P. & Hancock, E.G. 2000. Asymmetrical colour and wing-folding in Tithrone roseipennis (Saussure

1870), a Neotropical praying mantis (Mantodea Hymenopodidae). Tropical Zoology 12: 325 -334.

Burns, T.J., D.J. McCafferty, and M.W. Kennedy (2015) Core and body surface temperatures of nesting

leatherback turtles (Dermochelys coriacea). Journal of Thermal Biology 51, 15-22.

Downie, J.R., Nokhbatolfoghahai, M., Bruce,D.,Smith, J.M., Orthmann-Brask, N. & MacDonald-Allan, I. 2013.

Nest structure, incubation and hatching in the Trinidadian leaf-frog Phyllomedusa trinitatis. Phyllomedusa 11,

13-32.

Downie, J.R., Hancock, E.G., Stewart A. White, S.A., Broderick, A.C. & Godley, B.J. 2017. The Natural History

Contributions of the University of Glasgow Exploration Society: to Scotland and the World. The Glasgow

naturalist 26(4):

Hancock, E.G. 2016. A new species of Mycetobia from the Neotropical region with a note on Mycetobia limanda

Stone, 1966 (Diptera, Anisopodidae; Mycetobiinae). Entomologists Monthly Magazine, 152: 253-258.

Hancock, E.G., Rotheray, G.E. & Zumbado, M. 2000. A new larval habitat in Helius (Diptera, Limoniidae).

Entomologists monthly Magazine, 136: 91 - 93.

Hancock, E.G. & A. Ward. 1996. The effect of shade on the relative abundance of insects in water traps in the

tropics. The Entomologist 115(2): 91-96.

Nokhbatolfoghahai, M., Downie, J.R. & Pollock, C.J. 2015. Oviposition and development in the glass frog

Hyalinobatrachium orientale toagoense. Phyllomedusa 14, 3-17.

Ricarte, A., M. Ángeles Marcos-García, M.A., Hancock, E.G. & Rotheray, G.E. 2012. Revision of the New

World genus Quichuana Knab, 1913 (Diptera: Syrphidae) including description of 24 new species. Zoological

Journal of the Linnean Society 166: 72-131.

Ricarte A, Marcos-García MÁ, Hancock EG, Rotheray GE (2015) Neotropical Copestylum Macquart (Diptera:

Syrphidae) breeding in fruits and flowers, Including seven new species. PLoS ONE 10(11): 1-58

Rotheray, G.E., E.G. Hancock, M.-A. Marcos-Garcia. 2007. Neotropical Copestylum (Diptera, Syrphidae)

breeding in bromeliads (Bromeliadacea) including 22 new species. Zoological Journal of the Linnean Society

150: 267-317.

Villalobos, C. de, Hancock, E.G. & Zanca, F. 2004. Redescription and sexual dimorphism of Chordodes balzani

Camerano, 1896 (Nematomorpha). Journal of Natural History 38(18): 2305-2313.

Research on Neotropical insects

Grants have enabled the development of knowledge

and skills in tropical forest ecosystems in South and

Central America. Species diversity in Diptera has been

a principal interest, mainly in the Tipuloidea,

Anisopodoidea (e.g., Hancock, 2016) and Syrphidae.

Undergraduate 4th year Honours projects have been

supervised while other students helped with sampling

that produced publishable results (e.g., Barabas &

Hancock, 2000; Hancock & Ward, 1996; Villalobos, et

al., 2004).

The principal outcomes have arisen from applying

techniques developed in temperate woodlands for

sampling saproxylic (dead wood) habitats and

phytotelmata for insects . These latter water bodies

include rain-filled tree rot holes or ssubtended in plant

bracts. Many Bromeliaceae, one of the defining

families of the Neotropical Region, have water tanks,

in both epiphytic and terrestrial species. The

Syrphidae, Richardiidae and several nematocerous

families are characteristic flies in such habitats. These

water bodies can be transient such as within the

flowers of Heliconia spp. (Strelitziaceae) or longer

lasting as in bamboo stems. Trapped detritus support

the various faunas and vary in organic richness so

provide for a diverse range of taxa. Sampling also

includes sap flows on trees and decaying fruits,

flowers and stems. Percy Sladen grants acted as seed-

funding of studies that continue (e.g., Hancock, et al.,

2000; Ricarte, et al., 2012 & 2014; Rotheray, et al.,

2007). EGH

Glass frogs on a Heliconia leaf, just after

egg deposition (credit: Chris Pollock)

Thermobiology of nesting leatherback sea turtles

Leatherback turtles (Dermochelys coriacea) are the fourth

largest reptile (after crocodilians). They are unusual in

nesting in the tropics and migrating to cold northern and

southern oceans to feed on jellyfish. They can achieve this

because they are well insulated with fat, and large enough to

retain heat more efficiently than smaller species – they are

therefore termed ‘gigantothermic’. A crucial question is how

will leatherbacks fare in their tropical nesting grounds as the

oceans warm with climate change? Will there be a critical

temperature above which they cannot breed, or will they

need, or be able to change their nesting sites to cooler

climes. We have therefore been monitoring the core

temperatures of leatherbacks in Trinidad over several years,

and comparing them with the smaller hawksbill turtles

(Eretmochelys imbricata) that live in the tropics all year

round. We made measurements using infrared-detecting

thermometers provided by the Percy Sladen Trust. These

allow us to measure temperatures of freshly laid eggs that

would have equilibrated with the internal temperature of the

mothers (Burns, et. al., 2015). We thus take measurements

without disturbing or making contact with the nesting

females or their eggs. The graph shows our results over five

years. This unique dataset shows that leatherbacks range in

body temperatures more than would a species of mammal,

but that the population as a whole scarcely alters from year

to year. In contrast, hawksbills change substantially from

year to year, presumably by being more responsive to

seawater temperatures. It is conceivable that leatherbacks

may be highly susceptible to anthropogenic increases in sea

temperatures. MK

Nesting leatherback turtle

illustrating their large size

relative to a human. Note the

reddening of the animal’s

throat, possibly indicating

that they may be in danger of

over-heating when they are

not being cooled by seawater

(credit: Steve Garvie)

The body temperatures of

two species of sea turtle

as estimated from the

surface temperatures of

their freshly-laid eggs in

the years 2013 to 2017.

The leatherbacks were

studied on the east coast

of Trinidad, and the

hawksbills in the north of

the nearby island of

Tobago.

JRD sampling Phyllomedusa nests

Sampling Glomeropiitcairnia

bromeliad in elfin cloud forest,

El Tucuche, Trinidad