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A clutch of
eggs is the group of eggs produced by
birds
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
,
amphibians
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
, or
reptiles, often at a single time, particularly those laid in a
nest.
In birds, destruction of a clutch by
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill t ...
s (or removal by humans, for example the
California condor breeding program) results in ''double-clutching''. The technique is used to double the production of a species' eggs, in the California condor case, specifically to increase population size. The act of putting one's hand in a nest to remove eggs is known as "dipping the clutch".
Size
Clutch size differs greatly between
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
, sometimes even within the same
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
. It may also differ within the same
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
due to many factors including
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
, health, nutrition, predation pressures, and time of year.
Clutch size variation can also reflect variation in optimal reproduction effort. In birds, clutch size can vary within a species due to various features (age and health of laying female, ability of male to supply food, and abundance of prey), while some species are determinant layers, laying a species-specific number of eggs. Long-lived species tend to have smaller clutch sizes than short-lived species (see also
r/K selection theory
In ecology, ''r''/''K'' selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of indivi ...
). The evolution of optimal clutch size is also driven by other factors, such as
parent–offspring conflict.
In birds, ornithologist David Lack carried out much research into regulation of clutch size. In species with altricial young, he proposed that optimal clutch size was determined by the number of young a parent could feed until fledgling. In precocial birds, Lack determined that clutch size was determined by the nutrients available to egg-laying females. An experimental study in Black Brent Geese (Black Brant), which rarely lay more than five eggs, found that the probability of an egg successfully leading to a fledged gosling declined from 0.81 for two-egg clutches to 0.50 for seven-egg clutches, whilst the nesting period increased with the increasing number of eggs laid. This suggests that there is no benefit for female Black Brant to lay more than five eggs.
Gallery
Image:Anas platyrhynchos (nest).JPG, Mallard (''Anas platyrhynchos''), very large clutch or possibly from two females
Image:Larus marinus eggs.jpg, Great black-backed gull (''Larus marinus''), small clutch
Image:Masked Lapwing Eggs.jpg, Masked lapwing (''Vanellus miles''), typical clutch
Image:Waterhoennest.JPG, Common moorhen (''Gallinula chloropus''), small clutch
Image:Aquila pomarina nest with eggs.jpg, Lesser spotted eagle (''Aquila pomarina''), typical clutch
Image:Columba livia nest 2 eggs.jpg, Feral pigeon
Feral pigeons (''Columba livia domestica'' or ''Columba livia forma urbana''), also called city doves, city pigeons, or street pigeons,Nagy, Kelsi, and Johnson, Phillip David. ''Trash animals: how we live with natures filthy, feral, invasive, an ...
(''Columba livia domestica''), typical clutch
Image:Starling eggs.jpeg, European starling (''Sturnus vulgaris''), typical clutch
Image:Stieglitzgelege.jpg, European goldfinch (''Carduelis carduelis''), large clutch
Image:DesmognathusFuscusPageVA.jpg, Northern dusky salamander (''Desmognathus fuscus''), typical egg clutch
See also
*
Oology (the scientific study of eggs)
*
Viviparity
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...
References
{{reflist, 30em
Birds
Bird breeding
Aviculture
Oology