Climatic factors such as floods, storms, and extreme cold greatly affect human capacities to harvest and process animals used for food. Animals taken for food (e.g., salmon [Oncorhynchus spp.], whales [Cetacea], walrus [Odobenus rosmarus], caribou [Rangifer tarandus]) are generally available during relatively short periods in summer and early autumn; this is especially true for terrestrial wildlife (Chapter 6) and anadromous fish (Chapter 8) populations. Huge variations in abundance are possible, including near total collapse. Much of the year-to-year variation in wildlife populations can be attributed to variation in climatic factors.