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Diagram of the apparatus for measuring the pigeon's absolute visual threshold. (After D S. Blough, A method for obtaining psychophysical thresholds from the pigeon, J. Exp. Anal. Behav., 1:31–43, 1958)

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from article Air armament

Air Superiority Missile Concept.

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from article Air armament

Low-Cost Autonomous Attack System (LOCAAS; formerly Low-Cost Antiarmor Submunition). (a) Autonomous submunition, with length of 30 in. (0.75 m), wingspan of 40 in. (1.0 m), and weight of 90–100 lb (40–45 kg). (b) Various warhead modes.

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from article Reproductive behavior

The mating of dragonflies encompasses a number of reproductive behaviors. Typically, the male is in front and the female is behind. If the female is willing to mate, she bends her abdomen forward to collect sperm from the male's accessory genitalia,…

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from article Reproductive behavior

Sage-grouse lek. Males stake out and defend territories on a traditional breeding ground. Females breed with males in selected territories. (Credit: U.S. Fish and Wildlife Service)

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from article Reproductive behavior

Two bull northern elephant seals fighting for dominance on the beach. (Credit: eoind/Getty Images)

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from article Reproductive behavior

Natterjack toad giving a mating call with its vocal sac expanded. (Credit: Bobby Bok)

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from article Reproductive behavior

Mating behavior of sticklebacks: (a) zigzag dance of a male, which leads a female to the nest; (b) the male stimulates the female in the nest to lay eggs; (c) schematic portrayal of the events in a courtship sequence. (Credit: Based on original…

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from article Reproductive behavior

Lordosis in a female rodent. When mounted, the females of many mammalian species adopt the lordotic posture, rendering copulation possible. Note the concave arching of the spine. (Credit: Based on an original drawing by L. C. Drickamer and S. H.…

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from article Reproductive behavior