Marie Read / Black-necked stilts (Himantopus mexicanus) pair performing post-copulatory display (as copulation ends, the male slides off the female leaving his wings draped over her and crossing his bill with hers...

Donald M. Jones / Northern Pintail (Anas acuta) males flying with female in spring courtship display, Montana

Theo Bosboom / Variable damselfly (Coenagrion pulchellum) pair mating, De Peel National Park, the Netherlands, July.

Jussi Murtosaari / Blackcap (Sylvia atricapilla) female and two males huddling together for warmth while sleeping, Finland, May.

Francois Savigny / Old African elephant bull in 'must', period of sexual dominance when he wil mate with females in his home range, Etosha National Park, S. Africa

Ingo Arndt / Purple Heron (Ardea purpurea) pair courting and building nest in reeds, Germany

Thomas Marent / Velvet-purple Coronet (Boissonneaua jardini) hummingbird in defensive posture, Las Tangaras Bird Reserve, Colombia

Luciano Candisani / Green Anaconda (Eunectes murinus) female constricting male after copulation, after which she will consume him, Brazil

Eric Sohn Joo Tan/ BIA / Black-winged Lapwing (Vanellus melanopterus) calling during defensive display, KwaZulu-Natal, South Africa

Thomas Hinsche/ BIA / Common Buzzard (Buteo buteo) pair fighting, Saxony-Anhalt, Germany

Thomas Hinsche/ BIA / Common Buzzard (Buteo buteo) pair fighting, Saxony-Anhalt, Germany

Alan Murphy/ BIA / Killdeer (Charadrius vociferus) in broken wing display, Texas