Related by context. Frequent words. (Click for all words.) 74 migrated northward 56 drifting northward 55 Migrating birds 53 severe droughts 53 eastern Dakotas 53 Mosquito borne 53 Sea otters 52 Gypsy moths 52 sicken humans 52 northward migration 51 voracious predators 51 milder winters 51 pet prairie dogs 51 freshwater ponds 51 Infestations 50 dolphins wash ashore 50 shortnose sturgeon 50 subtropical regions 50 lowland gorillas 50 warmer wetter 50 tanagers 50 Sandhill cranes 50 Tornadoes rip 49 Paleo Indians 49 bears mountain lions 49 Purple loosestrife 49 Trumpeter swans 49 Barn owls 49 overwinters 49 temperate zones 49 worsening droughts 49 coastal lowlands 49 southward migration 49 Infant mortality rates 49 dunlin 49 grassy plains 49 Shasta glaciers 49 Whooping cranes 49 egrets herons 49 Ice Ages 49 Triassic Period 48 holocaust Racism hallmark 48 frogs salamanders 48 amphibians reptiles 48 Spanish Conquistadors 48 Severe drought 48 avian malaria 48 interbred 48 ancestors migrated 48 Armyworms 48 Warming temperatures 48 prairie pothole region 48 overhunting 48 frogs lizards 48 genetically distinct 48 overwintered 48 red bellied woodpeckers 48 delicate marshes 48 extirpated 48 arctic foxes 48 cattle egrets 47 auklets 47 elk bison 47 Purple martins 47 northern pintail 47 voracious eaters 47 insect eaters 47 leopard frog 47 Opossums 47 migrate northward 47 yellow legged frogs 47 Unusually warm 47 saltwater marshes 47 Pribilofs 47 penguins seals 47 song thrush 47 migratory ducks 47 lesser scaup 47 short tailed albatross 47 permafrost melts 47 spruce budworm 47 frogs toads 47 white crowned sparrows 47 Warmer winters 47 surf scoters 47 diamondbacks 47 migrating 47 woolly adelgid 46 Stink bugs 46 insectivores 46 Basking sharks 46 ring necked ducks 46 roseate spoonbills 46 song thrushes 46 preindustrial times 46 mosquito borne viral 46 Swollen rivers 46 Monkeypox 46 prolonged droughts 46 colder winters 46 leopard frogs