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Neotropical Migratory Birds

Neotropical Migratory Birds. Neotropical = ‘New Tropics’ New World vs old world Western Hemisphere Neotropical birds breed in Canada and the United States during the northern hemisphere’s summer and spends the rest of the year in the tropics.

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Neotropical Migratory Birds

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  1. Neotropical Migratory Birds • Neotropical = ‘New Tropics’ • New World vs old world • Western Hemisphere • Neotropical birds breed in Canada and the United States during the northern hemisphere’s summer and spends the rest of the year in the tropics. • Defined as a species in which the majority of individuals breed north of the Tropic of Cancer (latitude = 23 degrees north) • About 200 species

  2. Migration Distance • Varies across species and within species • Shortest (a few hundred miles) are those birds that breed in the southern US and overwinter in Mexico. • Some of the longest are birds that breed in the arctic tundra in northernmost Canada and winter as far south as the southermost tip of South America • One way mileage = 10,000 • Arctic Tern • Nests as far north as land extends • Overwinters near the south pole • Sees more daylight than any other species • Round trip covers about 22,000 miles.

  3. Why Migrate? • They can take advantage of seasonally abundant food supply and avoid times and places that food supply is low. • Flying insects, caterpillars, fruits and nectar are abundant during our spring and summer, but not winter. • Ultimate reason is breeding success. • Can raise more young if they migrate than if they stayed in the tropics. • Abundant protein-rich food, longer daylight hours, more room, possibly fewer predators.

  4. When To Migrate? • Internal clock controls the onset of migration and the premigration preparations. • Environmental factors control this clock • Certain changes in a bird’s environment stimulate the production of certain hormones, which leads to changes in behavior and physiology. • Change in day length for example

  5. How To Get There? • Short migraters and waterfowl generally learn breeding and wintering locations from older more experienced birds • Often family members • Most long distance migraters are genetically programmed to make the trip. • First migration is completely under genetic control • Subsequent trips may incorporate previous experiences (return each year to good reproductive grounds)

  6. Migration Routes • Follow land through Mexico into the United States • Cross the Gulf of Mexico • First/last encountered land important to survival • Rest and refueling

  7. Seasonal Habitats • Wintering Grounds • Sufficient food for premigration preparations • Migratory Habitat • Fat reserves, nutrients, vulnerability to predation • Breeding Grounds • Reproductive success

  8. Habitat Variety Important • With the diversity of migratory birds, a diversity of habitats is needed in the migratory habitats. • Reduces competition

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