Chicken Embryo
- A number of fine photographs of the development of a chick inside the egg.
- http://www.microscopy-uk.org.uk/mag/artnov04macro/mlchicken.html

When and How do Birds Migrate
- Article discussing the varying strategies adopted by birds in finding their way when taking part in their long distance journeys.
- http://www.earthlife.net/birds/migration2.html

Sense of Direction
- Article from the Princeton Weekly Bulletin outlining how Biologist Martin Wikelski is helping to settle the long-standing debate over how migratory birds manage to navigate in darkness and bad weather.
- http://www.princeton.edu/pr/pwb/04/0503/1b.shtml

EcoBirds Behaviour
- Provides a series of bird articles covering nesting, song, migration and the curious habit of anting.
- http://birds.ecoport.org/Behaviour/EBbehaviour.htm

The Atlas of Bird Migration
- Comprehensive article on the great challenge faced by long distance migrants which have to find their way to winter quarters and return to their breeding grounds in the spring.
- http://www.brownreference.com/php/PDFS/AN_Title_Information/457---Sample_Spreads.pdf

Teachers' Domain: Bird Beak Gallery
- Provides an essay on beaks, and photographs of birds heads and beaks.
- http://www.teachersdomain.org/resources/tdc02/sci/life/stru/beakgallery/index.html

The Normal Moulting Process in Birds
- Talk given by Avian Vet A. K. Jones to a conference of the Association of Avian Veterinarians in August 1998.
- http://www.parrotpassionsuk.com/Advice/Moulting.htm

Birdcall synthesis
- Article describing how birds use their syrinx, throat and beak to make a wide range of tones without the sophisticated muscle structure possessed by humans.
- http://www.obiwannabe.co.uk/tutorials/html/tutorial_birds.html

The Structure of Avian Skin and Feathers
- Technical article describing a bird's skin and associated structures, its feathers, beak, claws and spurs.
- http://pcwww.liv.ac.uk/~timn/THE%20STRUCTURE%20OF%20AVIAN%20SKIN%20AND%20FEATHERS.doc

Beak
- Article describing the anatomy of this distinctive feature of birds which, in addition to eating, can be used for grooming, manipulating objects, killing prey, probing for food, courtship, and feeding the young.
- http://www.ipedia.net/information/Beak

Urban Birds
- Article discussing how birds have adapted to urban foraging amid the artificial concrete and steel ecosystems of cities.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Urban_Birds.html

Bird Milk
- Article describing how the young of some birds are fed on special secretions from their parents.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Bird_Milk.html

Incubation: Heating the Egg
- Most birds create the required temperature by sitting on their eggs but some transfer heat through their webbed feet, and the megapodes of Australia bury them in a mound of decaying vegetation.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Incubation.html

Creches
- Article describing how some birds adopt the strategy of grouping their young, leaving them with a guardian while both parents go off to forage.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Creches.html

Parental Care
- The young of passerines when first hatched are naked, blind, and helpless and require much care which involves feeding, training and protection from predators.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Parental_Care.html

Polygyny
- Most birds are monogamous, but in some species the occurrence of polygyny, where one male mates with more than one female, is related to high-quality territories with an abundance of resources.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Polygyny.html

Sexual Selection
- Female birds of some species tend to choose as mates those males holding the most desirable territories, but there is little evidence that females preferentially select males with different degrees of ornamentation.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Sexual_Selection.html

Vocal Functions
- Songs identify the species of the singing bird. The territorial song of males serves the dual purpose of territorial proclamation directed at other males and of mate attraction directed toward females.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Vocal_Functions.html

Vocal Copying
- Article describing how birds learn their songs from adult tutors and may incorporate sounds from other species into their repertoire.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Vocal_Copying.html

Vocal Dialects
- Article describing how the songs of many avian species show geographic variation.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Vocal_Dialects.html

Territoriality
- Article describing how birds try to exclude others of the same species from their home range.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Territoriality.html

Raptor Information System
- The RIS is a free searchable catalog of over 38,000 references about the biology and management of birds of prey.
- http://ris.wr.usgs.gov

Index of Lectures
- A series of articles on different aspects of bird biology such as feathers, flight, respiration, territoriality, reproduction and metabolism.
- http://www.ornithology.com/lectures/Introduction.html

Feather Quest
- Interactive quiz. Can you identify the birds from which these feathers come?
- http://www.nmnh.si.edu/BIRDNET/FeatherQuest/FeatherQuest.html

Development and Uses of Avian Skeleton Collections
- Skeletons are essential for the identification of fossils, bones from archaeological sites and food items taken by predators as well as histological and physiological studies.
- http://www.boc-online.org/PDF/vol124/Storrs%20Olson.pdf

Animal Files: Birds
- Here you can find information on bird biology, bird mythology, symbolism, birds in shamanism and in dreams.
- http://www.dierinbeeld.nl/animal_files/birds/

Flight in Birds
- How do birds fly? An introduction to flight in birds examining wing shape, airflows, flapping flight and gliding.
- http://www.earthlife.net/birds/flight.html

Flapping Flight: Inertial Studies
- Technical article by researchers at Bristol University who measured the wings of bats and birds and calculated their efficiency in flight.
- http://jeb.biologists.org/cgi/reprint/198/8/1655

Site Tenacity
- Many birds return to the same nesting site each season. This essay discusses why this should be so.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Site_Tenacity.html

Population Dynamics
- Essay discussing the factors behind the variation in the number of individuals in a bird population over time.
- http://www.stanford.edu/group/stanfordbirds/text/essays/Population_Dynamics.html

A Qualitative and Quantitative Study of the Lung of an Ostrich
- The colossal body size, the relinquishment of flight and the extreme thermal stresses on the ground make the examination of an ostrich’s lungs rewarding.
- http://jeb.biologists.org/cgi/content/full/204/13/2313

Mechanics of Respiration in Birds
- Notes and diagrams explaining how birds ventilate their lungs.
- http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab26/Notes/birdresp.htm

Bird Respiratory System
- Article explaining how air sacs play an important part in the gaseous exchange in birds, with many diagrams.
- http://people.eku.edu/ritchisong/RITCHISO/birdrespiration.html

Avian Reproduction: Clutch Size, Incubation and Hatching
- Notes on clutch size optimization in birds, reproductive success, embryo development, incubation and the hatching process, with links to other similar articles.
- http://people.eku.edu/ritchisong/avianreproduction2.html

Avian Reproduction: Anatomy and the Bird Egg
- Notes on the bird reproductive system and the development of the embryo, with explanatory drawings and photographs.
- http://people.eku.edu/ritchisong/avianreproduction.html

List of Essays
- Many articles on every aspect of bird life. A comprehensive and useful resource.
- http://www.stanford.edu/group/stanfordbirds/SUFRAME.html

Smithsonian Migratory Bird Center
- Ecological and land-management research, education, conservation policy, data on migration and fact sheets.
- http://nationalzoo.si.edu/ConservationAndScience/MigratoryBirds/

Bird Skull Collection
- Images and data about skulls of western Palearctic and Tropical species, with complete skeletons of some species.
- http://www.skullsite.co.uk/

Birdnet
- Ornithological Council's website with comprehensive data about North American ornithological resources.
- http://www.nmnh.si.edu/BIRDNET/

Ornithological Web Library
- A comprehensive annotated library of over 1,800 ornithological and birding related links.
- http://www.aves.net/the-owl/

Electronic Resources on Ornithology
- Annotated links and ornithological articles by Christopher Majka.
- http://www.chebucto.ns.ca/Environment/NHR/bird.html

Ornithology: Science of Birds
- Includes data on the science of wild birds, with an emphasis on conservation and education.
- http://www.ornithology.com/