Dictionary G-L

This section is aimed at explaining the bird and biology specific vocabulary you are likely to meet in other threads in Birdforum.

This page is divided into four sections: Dictionary A-F, Dictionary G-L, Dictionary M-S and Dictionary T-Z.

G

Gape: see Heads.

Gloger's rule: a zoogeographic rule stating that animals living in a warmer, more humid environment tends to be darker than those living in cooler, dryer areas.

Gonys: see Beaks. Related expressions are gonys spot, gonys angle = gondyeal angle also explained in the link.

H

Homoplasy: is used to describe that two species are identical in some trait not because of common ancestry but because of convergent evolution or random genetic events. As example of convergent evolution, compare the mouth of some small, insect eating marsupials in Australia with shrews in Europe; they are fairly much identical because they are selected to efficiently solve the same problem, catching and eating insects.

Hybrid, Hybridization: a hybrid is the offspring of a mating between parents belonging to two different species or subspecies. A well known example is the mule, which is a hybrid between horse and donkey. Hybridization between distantly related species will most often result in infertile offspring, while more closely related species might result in offspring that seems fully fertile but still has selective disadvantages meaning that in the big picture, the two forms does stay distinct. On the other hand, hybridization between subspecies by definition would result in fertile offspring; if there is reduced fertility or selective disadvantage, then the two groups might be on the way to becoming full species. Examples of bird hybrids found reasonably frequently would be hybrids between ducks in genus Anas or in genus Aythya or geese including Canada Goose x geese of either genus Branta or Anser.

I

Immature (there are two usages of this term):

• 1: strictly speaking, this includes all plumages after juvenile and before full adult plumage is attained². The number of immature plumages can therefore vary widely between groups of species.
• 2: many authors do not really distinguish between juvenile/juvenal and immature¹.

Iridescence: see Diffraction at D

Iris: see Heads

References

1. Erritzoe et al. 2007. The Ornithologist's Dictionary. Lynx Edicions, Barcelona, Spain. ISBN 84-96553-43-4
2. Pyle, Peter 1997. Identification Guide to North American Birds, Part 1. Slate Creek Press, Bolinas, California. ISBN 0-9618940-2-4

J

Juvenile: (synonymous with Juvenal) the first plumage with real feathers, reached by molt from the downy plumage of a nestling or pullus. Strictly, this is a plumage that will be followed by either the first adult plumage or by the plumage of an immature; however, there seems to be great confusion, and many will use juvenile and immature as synonymous. The juvenile feathers often are different than the feathers of later plumages: firstly, they often push out the downs that they replace, and the down may remain attached to the tip of the juvenile feather for a while; secondly, the body feathers often are more fluffy and downy than later feathers; and thirdly, tail feathers in passerines often are more pointed then tail feathers of later plumages. Erritzoe et al. proposes a change in usage so that a juvenile bird is any "young bird that is out of its nest and able to care for itself".

References

1. Erritzoe et al. 2007. The Ornithologist's Dictionary. Lynx Edicions, Barcelona, Spain. ISBN 84-96553-43-4
2. Pyle, Peter 1997. Identification Guide to North American Birds, Part 1. Slate Creek Press, Bolinas, California. ISBN 0-9618940-2-4

L

Lek, lekking: lekking is the behavior where males display in groups hoping that a female will choose one of the displaying males to mate with. Lek can therefore mean such a group, but it can also mean the place where such behavior takes place (colloquially called mating arena). Ruff and Manakins are examples of birds known for their lekking, but lekking happens in several additional groups.

Lore: (more often used in plural, lores) see Heads

This page is divided into four sections: Dictionary A-F, Dictionary G-L, Dictionary M-S and Dictionary T-Z.