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The Ins and Outs of Identification

By Rebecca Pitkin 2 years ago
Categories Phang Nga

   Do you know your Calotes emma from your Calotes versicalor? Would you know how to identify the reptiles in the photographs above (photo left)? Identifying different species isn’t always easy, but it’s an important skill when you’re monitoring regional biodiversity. Here in Phang Nga we work closely with the Thailand National Park Authority tracking the animals found within two forests in the local area: Lampi and Ton Prai. Through our surveys, we have identified 269 species, recorded in our shared database complete with vital photographs. Such catalogues are an important tool in protecting diversity; they allow our partners to know exactly what is within a habitat, a necessary first step in conserving it. As our work continues, new animals are being found, and these must all be identified before we can add them to our records and reports: a process which can be time consuming, and hinges on having good quality images and detailed field guides (both physical and digital).

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   Just last week, Joe spotted this well-camouflaged invertebrate hanging out on a branch in Lampi (photo right). Dave, armed with his trusty digital SLR, captured a series of photos. Invertebrates can be notoriously difficult to ID, and require us to have images of as many different angles and aspects as possible. The challenge is in part due to the number of invertebrates out there. 95% of all animal species are invertebrates, meaning there are lots to filter through when trying to pin an identity down. In addition, it’s easy to misidentify them, since the differences between species can be very subtle, while the intraspecific variations can be large, for instance during different growth stages. Finally, it’s estimated that 80% of invertebrates are still undocumented, so it’s possible you’re looking at something which hasn’t yet been classified.

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   Different classes of animal present different challenges. Like invertebrates, amphibians can be tricky. Colour varies widely within a species, so individuals of the same species can look completely different at first glance. The key to identifying them is to get a good look at every aspect of the animal, particularly the key morphological points: head, eye and limb size, body width. For reptiles, three distinct sections are important: in snakes, the head, body and tail all hold key identifying features; in butterflies we try to ensure we have a good record of their head, dorsal and ventral sides. Birds are typically easier, but only if you can get a good look at them; they are often high up and partly obscured by foliage or unfavourable lighting (viewing them against a bright sky mutes out the colour of their plumage).

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   Once back at base, we were able to consult our guides and databases. Because analysis takes both time and varied resources, we usually complete this kind of work out of the field. Birds are perhaps the only exception, and our well-thumbed books (coupled with decent binoculars) will come out with us on the surveys. For other classes, notably the reptiles and invertebrates, we use a combination of online sources, such as the iNaturalist database or even Google images. In all cases, the knack often hinges on exploiting your existing knowledge to get a rough steer on the family and genus first: it really helps to know that the bird you’ve seen looks quite like a heron, for example. Even so, classification takes time, sometimes upwards of an hour, and at times (particularly with invertebrates) we’re still left at the genus level rather than species.

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   With Joe’s find above, our initial guess was that this was some sort of stick insect; a good starting point, but with over 3000 species found globally, we still had plenty of searching and filtering to do. Location was a good place to start, and a search on stick insects of southern Thailand presented a few potential leads. In particular we were able to find images of a species which was similar to the one we had seen, giving us a scientific name on which we could refine further. This was the find we needed, as a new search brought up some promising pictures of a similar species known as Heteropteryx dilatata or Jungle Nymph, one of the world’s heaviest bugs. After reviewing the available data on this one we had the ID confirmation we needed to add it to our database. This was indeed a Jungle Nymph: the 269th species to be found in the Thai Muang National Parks, and a pleasing new addition to our records!

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Written by Rebecca Pitkin, 12 week Marine Coastal Conservation volunteer

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