Table 3. Examples of human-induced nonbreeding impacts on population dynamics of diverse seasonal migrants, as suggested by empirical studies. Nonbreeding season event Suggested population impact Taxonomic group(s) Studies HABITAT CHANGE Tropical deforestation (winter habitat) decline in abundance passerines Robbins et al. 1989, Rappole & McDonald 1994, Haney et al. 1998   minor relative to other factors passerines Bohning-Gaese et al. 1993, Latta & Baltz 1997   Coastal habitat destruction decline in abundance shorebirds Norris et al. 2004b, Drent et al. 2006 Depletion of stopover food source reduced survival, abundance shorebirds Baker et al. 2004 Loss of winter, staging habitat decline in abundance waterfowl Pettifor et al. 2000 Increase in agricultural development increased migration survival waterfowl Gauthier et al. 2005 River damming (breeding/migration habitat) reduced migration survival salmonids Ratner et al. 1997, Kareiva et al. 2000, Wilson 2003   disruption of metapopulation salmonids Fraser et al. 2007   Agricultural development and fencing decline in abundance ungulates Bolger et al. 2008 Human settlement, farming, fencing interruption of migration route terrestrial mammals Berger 2004, Thirgood et al. 2004   CLIMATIC VARIABILITY Change in winter climate fluctuations in abundance butterflies Vandenbosch 2003 Increase in winter/spring temperature improved survival, reproduction waterfowl Lehikoinen et al. 2006, Kéry et al. 2006 Sudden weather changes, storms mortality during migration birds (various) Newton 2007 (review) Change in ocean temperature reduced nonbreeding survival salmonids Friedland et al. 1993, Bisbal & McConnaha 1998   variation in breeding frequency   seabirds, sea turtles Lee et al. 2007, Saba et al. 2007 Variation in dry-season rainfall reduced annual survival ungulates Owen-Smith et al. 2005 Decline in climate-linked food sources reduced reproductive success birds (general) Bairlein & Huppop 2004, Ward et al. 2005, Lee et al. 2007 Variable seasonal rates of change mistimed breeding phenology shorebirds; passerines Stenseth & Mysterud 2002, Drent et al. 2003, Both et al. 2006   MORTALITY/DISTURBANCE Sport harvest reduced nonbreeding survival waterfowl; salmonids Menu et al. 2002, Calvert & Gauthier 2005, Quinn 2005 Declining sport harvest increased survival waterfowl Gauthier et al. 2005 Disturbance at staging sites reduced pre-breeding condition waterfowl Mainguy et al. 2002, Klaassen et al. 2006 Ship collision/gear entanglement reduced nonbreeding survival marine mammals Caswell et al. 1999, Runge et al. 2004, Kraus et al. 2005 Fisheries bycatch reduced nonbreeding survival marine reptiles; seabirds Crowder et al. 1994, Cuthbert et al. 2001, James et al. 2005, Phillips et al. 2005