Tui De Roy / Salvin's Albatross (Thalassarche salvini) returning en masse to crowded nesting colony at sunset, Proclamation Island, Bounty Islands, New Zealand
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Floris van Breugel / Hibernating Ladybirds (Hippodamia convergens) assembled en masse to overwinter, King's Canyon National Park, California, USA, May 2009
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Andy Sands / Water avens (Geum rivale) growing en-masse on roadside verge, Upper Teesdale, Co. Durham, England, UK, June
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Pete Oxford / Communal caterpillars travelling en masse for protection to make predators think they are larger. Amazonia, Peru
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Michael Quinton / Pink Salmon (Oncorhynchus gorbuscha) spawning en masse, Alaska
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Michael Quinton / Pink Salmon (Oncorhynchus gorbuscha) spawning en masse, Alaska
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Michael Quinton / Pink Salmon (Oncorhynchus gorbuscha) spawning en masse, Alaska
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Peter Blackwell / Wildebeest crossing river en masse {Connochaetes taurinus} Masai Mara, Kenya, Africa
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Peter Blackwell / Wildebeest (Connochaetes taurinus) crossing river en masse. Masai Mara, Kenya, East Africa