The Teal

First a simple fact - near exactly one third of the book is appendices and references.
Perhaps because neither author is English, but apparently us English call Anas (c.) crecca, "common teal". Well, I have never heard it called that. Unlike a great deal of Europe and the Americas, the UK has only a single tiny dabbling duck species that is at all common and this is it - teal, no qualification, just teal. If this were not so, the book's title wouldn't make much sense, or at least be highly imprecise.

Now, an unforgiveable, terrible schoolboy error - Fig. 9.7 shows two colour mutation teal with the caption that includes - "..... breeders have produced a range of Teal varieties in captivity .....". Totally and utterly incorrect.

Natural genetic mutation produced the changes in colour, which a degree of inbreeding in captive stocks made visible (most colour mutations are recessive, so that an individual has to carry two copies of the controlling gene(s), one from each parent, to show its effect, in this case a change in colour. That gene is almost certainly inherited from an ancestor common to both parents as genetic mutations such as these are so very rare that the same mutation occurring twice in close proximity and time, are all but nil). Man has guaranteed perpetuation of the genetic mutation by selective breeding, but no person ever produced it.

Are these colour mutations, varieties? No, not in any normally accepted sense, they are simply colour variants/mutations.

Chapter 2 starts - ""Like most dabbling ducks, teal show a strong sexual plumage dimorphism." There are around 50 species of dabbling ducks; a quick survey reveals that only around a third show marked sexual dimorphism (it depends on how a species is defined and where you draw the line for "strong ... dimorphism").

On page 29, it states - " In North America only Baikal Teal..., Blue-winged Teal and Cinnamon Teal...................". Why mention Baikal teal when the species is a staggeringly rare vagrant to Canada and even rarer in the 48 contiguous US states (total confirmed NA records, ever, are around 20 sightings - mostly in the Aleutians)?

Pp 30-32, a very great deal of detail is gone into on how to sex teal in the hand, much of it using very subjective features. Not one mention of vent-sexing which can be performed on day-olds upwards - something of a skill, but easily learned. No mention of sexual differences in beak colouration either, where differences appear early in life, persist throughout the moult and are useful in the field if suitable binoculars or a telescope is available.

The remaining contents reveal little that anyone interested in anatids would not at least have some idea about, although the discussion about the genetics of the NA and Eurasian (sub)-species is comprehensive and something that I have not seen in this much detail, in one place before.

Looking back across my collection of Poyser monographs, some authors have approached their subject from life-long personal field observation, while others have created a very thorough shake-down of research carried out by many people. The book is in the latter camp.

My comment is not intended as a snub – Matthieu Guillemain is a Research Fellow at Tour du Valat in the Camargue in France, and Johan Elmberg is Professor of Animal Ecology at Kristianstad University in Sweden. There are few people who have their level of experience in assessing the population and ecology of waterfowl. The approach that they take is therefore primarily academic as they summarise all that is known about the “Teal”.

Despite the book’s title, it is in fact about two forms – Common Teal and Green-winged Teal, which are still treated as one by the American Ornithologists Union and also in the Howard and Moore checklist. Most European records panels have chosen to split them, as do the IOC and Clements checklists. However what becomes clear as you read the text, is that apart from fairly minor plumage and size differences, these two species appear to share identical lifestyles. Indeed the authors summarise recent evidence presented by Jeffrey Peters and others that claim the gene flow between both species is still too great to allow them to become separate species.

Although these are common species I was struck by the challenges they face in their relatively short lives, both on the breeding and wintering grounds. Living in the UK It is easy to think of them as resident, but our situation is unusual, because in most countries are these are primarily or completely migratory species. This is particularly the case for Green-winged Teal which are able to travel much further south than Common Teal due to habitat limitations in Europe, North Africa and Asia.

The book covers all of the key areas that you would expect – distribution, population trends, foraging ecology, breeding behaviour and population dynamics. Both species of Teal are major targets for hunters and so there are sections on management and conservation too.

Although all Poyser monographs are always highly factual, some of the past authors have weaved their facts into a very readable text. This book is somewhat clinical in comparison, and given the backgrounds of the authors that is what you might expect. Every chapter is full of facts about wildfowl ecology, showing how these two Teal species compare to others within the family. In fact by reading this book you will encounter a lot of information about wildfowl in general, and at times I felt that this rather overshadowed the data on the Common and Green-winged Teal themselves.

A series of Appendices covering almost 100 pages provide a great level of detail on population numbers by country, key wintering sites and a detailed list of food items (the latter covering 23 pages!). There is also a summary table of 42 Avian Influenza Virus strains that have been found in either species, plus a long list of parasites and ectoparasites that have been found using Common or Green-winged Teals. There is also of bibliography of around 800 papers and publications.