Question | Answer |
Rapport's rule | latitudinal ranges of plants and animals are generally smaller at low than at high latitudes |
What are 3 strategies for northern living? | 1. permanent residents 2. short-distance migrants (winter in temperate areas) 3. long-distance migrants (wintering in the tropics) |
Define Nearctic | the zoogeographic region of North America, Greenland and N Mexico |
Palaearctic | the zoogeographic region of Europe, North Africa, W Asia, Siberia, N China, Japan |
Holarctic | the zoogeographic region comprising the Nearctic and Palaearctic |
Zoogeography | study of the geographical distribution of animals and animal communities |
Tree cavities | hollowed out portions of live or dead trees originating from….. • Natural (non-animal) agents – decay or physical damage, fungus, broken limbs • Excavation – usually by woodpeckers |
Primary Excavators | species that create their own cavity, usually woodpeckers |
Weak Excavators | can create their own cavity but also often renovate, enlarge or otherwise use existing cavities, e.g. chickadees, nuthatches |
Secondary Cavity Nesters / Users | cannot create their own cavity, rely on those created by primary or weak excavators or natural cavities, e.g. swallows, ducks, |
Why use cavities? | 1. avoid predation 2. Refuge from weather – more stable temperature, drier, less wind, generally warmer when nesting, but especially for single and communal roosting in cold weather (nuthatches, bats) |
Synchronous hatching | because eggs are all incubated at the same time, the eggs in a clutch all hatch at the same time, even though egg laid over 2 weeks |
What are the benefits of migrating north? | long photoperiod – allows more time for foraging • abundant food (but limited over time) • reduced competition |
capital breeders | accumulate nutrient reserves before breeding and these are used to form the eggs (e.g., geese) |
income breeders | ingest food and immediately divert a fraction into egg formation without relying on stored reserves |
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