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Migration
Falconiformes
3 families, 304 species
Worldwide distribution
Accipitridae
• Eagles, hawks, kites,
Old World vultures
• 233 species
European Sea Eagles
Old World Vultures
15 species
Many threatened
Griffon Vulture
Cathartidae
New World Vultures
7 species
King Vulture
California Condor
Pervious nares, urohydrosis
Falconidae
• Caracaras, falcons
and falconets
• 64 species
Gyrfalcon
Merlin
Migration
Migration
What is migration?
What are its advantages?
General features
Definition
Population movements in a predictable
direction at predictable times of year
between breeding areas and one or more
non-breeding areas
Advantages of migration
1) Avoid harsh climate
2) Secure more abundant food
3) Longer days for feeding young in the
north (clutch size increases in the north)
4) May reduce predation
5) Reduces disease and parasites
6) Increase space available for each pair
7) Genetic selection for fitness?
Migration timing
• Varies by species
• Varies from year to year
depending upon weather
• Some species remarkably
consistent
Since 1777, Cliff
Swallows have
arrived the week of
March 19th
Short-tailed Shearwater
South Australia
Non-migratory movements
Dispersal
Irruption
Nomadism
Dispersal
• Natal – away from birth place
• Breeding – away from breeding place
Movements typically unidirectional
Irruption
• Mass movement away from usual range
• Typically caused by food shortage
Nomadism
• Irregular, seemingly random movements
General Features
• ca. 4,000 bird species
migrate (42%)
• Most from temperate or
high latitudes
• Geographic asymmetry
Old World asymmetry
even greater
New World Warblers
Migration study methods
Banding/radiotracking
Direct observation
Radar
Laboratory studies
Site fidelity
Ovenbird
General Features
Migrate faster in spring than fall
and
adults travel faster than young
Day v night
Most small birds migrate at night
(stopping by 2 a.m.) and feed
during the day
Duration
James Bay to Louisiana
(2,700 km) in 60 hrs
1,100 km/day or 46 km/hr
Radar gives 30-70 km/hr for
most species
Speed
Northward in spring at
32 km/day
Black-and-white Warbler
Altitude
Most species fly at 1,500 m or
less during the day,
higher at night
Rueppell’s Griffon 37,000’
Ivory Coast
Bar-headed Goose 27,880’
Himalayas
Yellow-billed Chough 26,900’ Himalayas
Long-distance v short-distant
migrants
Long-distance migrant
Short-distance migrant
Longest distance migrant
35,000 km
Partial v Complete Migrants
Fox Sparrow
Ringed Plover
Loop
Migration
720,000 miles/gallon!
Physiological Preparation
• Short days trigger hyperphagia
• Nocturnal restlessness
• Zugunruhe – captive birds hop and flutter
in normal migration direction
• Warm weather inc zugunruhe in spring,
cold weather depresses it
• Castrated birds still exhibit zugunruhe
Barriers to migration can shape
species diversity
•
•
•
•
Large bodies of water
Mountain ranges
Inhospitable habitat
Western warbler
example
Number of warbler species
Western NA
12
(Wash., Ore., Ca)
Eastern NA
38
Europe
50