A History of Birdwatching in 100 Objects

Thermal cyclers (top) belong in the lab and not the field, but in the case of cryptic species, if we really want to know what we are looking at, then sometimes they are essential. Such technology solved the mystery of the Flamborough Flycatcher (right), initially thought to be an Atlas Flycatcher (left) but revealed to be a Pied Flycatcher (centre).

An apparent bane of the traditional birder’s life is the cryptic species, an entity now more prevalent as the process of DNA analysis and the production of phylogenetic trees have become increasingly important in taxonomy and biology.

The discovery of DNA’s correct form by Watson and Crick in 1953 and the realisation that each species carries its own unique arrangement of this chemical code could only have confused an ornithological world which relied on physical dissimilarity for its identification of bird forms.

The first fairly comprehensive revision of bird relationships by Sibley and Ahlquist in 1990 used the DNA-DNA hybridisation technique, in which DNA from one species is labelled and compared with another’s in the hope of determining how closely related it is. Some of their conclusions are controversial or, like the claimed close relationship between New World vultures and storks, now largely disproved by later refinements, but it was the first and most major in a long line of taxonomic reshuffles which have continued to illuminate relationships between bird species.

The large-scale analysis of small quantities of DNA – for instance, that taken from the toe pads of bird specimens – was made possible by the polymerase chain reaction (PCR) technique. Thermal cycling – heating and cooling in rotation – to produce a polymerase chain reaction was first tried by biotechnology firms in 1983, using an enzyme from a heat-resistant bacterium to ‘unzip’ DNA into single strands and ‘amplify’ these exponentially until they can be detected, identified and compared. A formal in vitro procedure was invented in 1985, but the first machine was developed by the American laboratory machine suppliers Perkin Elmer in 1987. These machines, despite costing between $5,000 and $10,000, became the standard for biologists and forensic scientists until the end of the 1990s. Now they can be obtained at online auction for around $150, but disputes over the various patents associated with the technique and the enzymes used have continued to this day.

This process is still viable, and enables scientists to produce phylogenetic trees to show interlinking evolutionary relationships and to identify mystery birds like the ‘Flamborough flycatcher’ in 2012, which was initially thought on plumage to be Britain’s first Atlas Flycatcher, but shown in the laboratory to be a straightforward Pied Flycatcher.