Tuesday, 26 November 2013

Identifications and recording

Whilst many of our species can easily be identified on sight, a far greater number require more detailed analysis. This analysis takes many forms, and can vary from measurements, counting features, rearing/breeding, chemical reactions and microscopic analysis through to dissection. Many of the features can be microscopic, which will require a specimen to be collected, captured or perhaps killed.

Identifications can be performed at varying levels of abstraction e.g. to family or genus, or carried out to the precise species (or subspecies!). In order to arrive at a species identification, we usually rely on keys. Keys are constructed in different ways, but the principle is always the same: by comparing features in a systematic way, and taking different routes through the key depending on analysed features, we arrive at an identification.

Once we have a tentative identification, we must then look at the species description to confirm that details such as geographic distribution, phenology (timing and location), host(s) and habitat match to a reasonable extent. If some features do not match well (for example your specimen is many hundreds of miles from the nearest previous sighting) then further assistance will need to be sought from more experienced person(s). If none of the details match, then the identification is probably wrong and the specimen should be taken through the key(s) again.

Identification keys are like gold dust to naturalists: many are out of print, so we need to seek rare (and frequently expensive) books or to find a source of 'draft keys' which are sometimes circulated for comment/testing/approval.

A further complication is that some keys only identify to an abstract level such as family or genus, so we need additional keys to get our specimen to species. These books are often written by different authors at different dates, so terminology can vary. This means that we might need to learn the specific terminology used in different parts of the key, leading to the need for a glossary for each book. So already we can see that some identifications will require at least four books and a microscope (or two) to be in use at the same time. Some keys run to hundreds or even thousands of pages.

Some keys work at the local level (usually country), but some are aggregated across countries (e.g. Northern Europe) and can be written in different languages. So we might also need a dictionary or two. One serious drawback of the multi-national identifications is that they will probably include species not (yet!) found in our own country, so we will also need access to country checklists for the family we are considering. This will give further assistance when considering tentative identifications, but are also useful when identifying a 'country first'.

Finally, ongoing research and changing phenology due, in part, to global warming can mean that we are working with a moving target with new species to consider in our task. Some of this changing work has not yet reached the books, so we need access to articles and papers in various publications in order to keep up to date.

Most people nowadays specialise in a small number of groups, so need only a restricted amount of relevant documentation, but others, like myself, are 'pan-species listers' (generalists) so we need a library that grows exponentially over time. The main benefits of being a generalist, however, are the ability to see across groups and to have a good overall picture of what's going on.

Records are a formal way of documenting where and when a specimen has been found. The minimum information for a record is species name, location name, date, grid reference and name of person making the record. Additional features will be required for different groups. e.g. host plant for fungal rusts, miners and parasites, lifecycle stage for moths, butterflies and other insects, substrate for lichens and mosses. Most recording schemes have a specific recording format that needs to be completed when submitting records for that group, and this will specify any additional data fields that are required.. Records are compiled by 'recorders', who generally work at the vice-county level, although some will work at county or even country level. Recorders are ideally people who are experts in their particular group(s) and will have a methodical way of compiling/aggregating and validating their records. Some records, especially county firsts or country firsts, will usually expect to be accompanied by a specimen. These records are eventually filtered up to the national records database for their particular country. Specimens for country firsts are often curated in national museums.

National records databases are a vital source of information on movements of species (spread, new arrivals or departures) and can be used to detect areas requiring further analysis or assistance. Various initiatives are used to stimulate the flow of records, including bioblitzes and school projects.

I have submitted a (rather late) record for this Common Wasp - Vespula vulgaris - that I found wandering on an indoors window at the weekend:

Vespula vulgaris

Vespula vulgaris - face
This very fresh (shiny carapace with long hairs still in place) worker had emerged very late in the year, long after the nest would have been abandoned. Note that the face is very round, ignoring the jaws: this is a key feature which separates the Vespula genus from the Dolichovespula genus. In Dolichovespula species, the gap between the bottom of the eye and the top of the jaw (the 'malar space') is much larger, leading to a vertically oval, or long,  face. Here's an archive (2010) shot of a male Dolichovespula norwegicus to illustrate the difference:
Dolichovespula norwegica, showing the larger 'malar space'

3 comments:

The Weaver of Grass said...

We found a very similar wasp in our kitchen last week Stuart - I thought it was probably a queen wasp but I see now that I might easily have been wrong. Sadly I didn't keep it for identification - the farmer managed to kill it - I was scared of being stung!

Gill said...

Fascinating. I think a record also requires the date seen?

As global warming changes our flora and fauna records are ever more valuable.

stuart dunlop said...

"I think a record also requires the date seen?"

Oops....only missed a really important one. Sorted, thanks....:)