Pen

A pen with cygnets.

A female swan . In the Whistling Swan and Mute Swan, the male stands guard while the female incubates the eggs . Males tend to be larger than females . Mute Swan cobs tend to have a larger knob on the bill than the pens .

References

^A Listed under Mute Swan, Trumpeter Swan and Whistling Swan ^{pp. 237-8}.

This article is part of Project Glossary, an All Birds project that aims to write comprehensive articles on each term related to animals.

Project Glossary
Glossary v • t • e A Abdomen • Aberrant • Abmigration • Abrasion • Absolute magnitude • Absorption line • Abyssal • Abyssal plain • Abyssal zone • Accelerating universe • Accidental • Accretion • Acquisition • Active galaxy • Active prominence • Adaptive radiation • Addition • Adult • Adult plumage • Aerie • African parrot • Air mass • Air sac • Airfoil • Alarm call • Albedo • Albino • Allopatric • Allopreening • Altazimuth mounting • Altitude • Altricial • Alula • Americas • Anadromous • Anaerobic • Anatomy • Annual parallax • Annual proper motion • Annualar eclipse • Anoxic • Antarctic Circle • Ant-follower • Anterior • Anticyclone • Anting • Antimatter • Antiparticle • Antiphonal song • Aperture • Apogee • Apparent magnitude • Arachnoid • Arboreal • Arctic Circle • Argon • Arm • Asexual reproduction • Asterism • Asteroid • Astronomical unit • Asynchronous hatching • Atmosphere • Atoll • Atom • Auricular • Auricular patch • Aurora • Autapomorphy • Authigenic • Autotroph • Autumnal equinox • Avian influenza • Axillaries • Azimuth B Back • Background radiation • Backshore • Backwash • Baleen • Band • Bank • Bar • Barbel • Barbule • Barnard • Barrage • Barred • Barred spiral galaxy • Barrier island • Barrier reef • Baryon • Basal (phylogenetics) • Basic I • Basin • Bathyal • Beach face • Belly • Beryllium • Benthos • Berm • Bib • Big Bang • Big Crunch • Big Rip • Binary star • Binomial nomenclature • Biodiversity • Biogenic • Bioluminescence • Biomass • Biome • Bioturbation • Bipedalism • Bird anatomy • Bird diets • Bird egg • Bird flight • Bird hybrid • Bird intelligence • Bird migration • Bird nest • Bird of prey • Bird reproduction • Bird senses • Bird song • Black body • Black dwarf star • Black hole • Black smoker • Blazar • BL lacterae object • Bloom • Blue shift • Body fossil • Bok globule • Booted • Bore • Brackish • Breaker zone • Breakwater • Breast • Breastband • Breeding plumage • Brood parasite • Brown dwarf star • Bustle • Buzzard • Bycatch C Calcareous • Calcium carbonate • Calendar year • Caldera • Callosity • Calve • Carapace • Carbon cycle • Carnivore • Carpal • Carpal bar • Casque • Casual • Catadromous • Cere • Cheek • Chemosynthesis • Chevron • Chin • Chlorophyll • Chromatophore • Cilia • Clade • Class • Cline • Cloaca • Coast • Cob • Cold seep • Collar • Colonial • Colour morph • Commensalism • Commic terns • Commissure • Common name • Concordant coast • Congeneric • Conservation status • Conspecific • Continental crust • Continental margin • Continental rise • Continental shelf • Continental slope • Convection • Convergent evolution • Coral bleaching • Coral reef • Coralline • Coriolis effect • Coverts • Crepuscular • Crest • Cretaceous • Crissum • Critically Endangered • Crown • Crown patch • Cryptic • Culmen • Current • Cusp • Cyclone D Dactyly • Dark zone • Dawn chorus • Deforestation • Delta • Demersal • Deposit feeding • Depositional coast • Detritus • Deuterium • Dewlap • Diagnostic • Digital object identifier • Dihedral • Discordant coast • DNA • DNA sequence • Doldrums • Dorsal • Drift • Drowned coast • Dune E Ear tuft • Earth • Echolocation • Echo-sounding • Eclipse plumage • Eddy • Egg • Egg tooth • Ekman effect • El Nino • Emargination • Emergent coast • Endangered • Endangered species • Endemic • Endemism • ENSO • Eocene • Equator • Erosional coast • Estuary • Eustatic • Eutrophication • Evolution of birds • Extant • Extinct • Extinct in the wild • Extinction • Exoskeleton • Eye • Eye line • Eye ring • Eye stripe • Eye wattle • Eyebrow F Face skin • Facial disk • Family • Fast ice • Fathom • Fault •Feather • Feather fringe • Fecal sac • Femur • Feral • Ferrel cell • Fertilization • Fetch • Filoplume • Filter feeding • Finger • Fjord • Flagellum • Flank • Fledgling • Flight feathers • Flightless bird • Flipper • Fluke • Foot • Foot projection • Forced wave • Forecrown • Forehead • Foreneck • Foreshore • Forest • Forewing • Fossil • Fractal • Frazil ice • Fringing reef • Frons • Front • Frontal shield G Gabion • Gander • Gape • Gape flange • Genus • Gibber • Gill rakers • Glacier • Gleaning • Glide • Gonydeal angle • Gonys • Gorget • Gravitational lens • Grease ice • Grease ice • Groyne • Guano • Gular • Gular fluttering • Guyot • Gynandromorph • Gyre H H1N1 • Habitat • Habitat loss • Hackle • Hadal • Hadley cell • Half-hood • Halocline • Hand • Hatchling • Hawk • Headland • Heat capacity • Helium • Herbig-Haro object • Herbivore • Hermaphrodite • Hibernation • Hindneck • Holdfast • Holoplankton • Hood • Hotspot • Hover • Humerus • Hurricane • Hybrid • Hydrocarbon • Hydrogen • Hydrothermal vent I-K Ice age • Iceberg • Ice cap • Ice lead • Ice rafting • Ice sheet • Ice shelf • Igneous rock • Immature • Incertae sedis • Infraorder • Insectivore • Intermediate coast • Internal wave • International Standard Book Number • Introduced species • Intertropical convergence zone • Invertebrate • Iridescence • Irradiance • Irruption • Island arc • Isolating mechanisms • Isotasy • IUCN • Juvenile • Katabatic wind • Keel • Kite (verb) • Kleptoparasitism • Krypton