Lecture 7 Annual Cycles, Migration & Navigation. Chapters 9 & 10 from Gill

Transcription

1 Lecture 7 Annual Cycles, Migration & Navigation Chapters 9 & 10 from Gill

2 Figure 9-1 Example of the Mallard

3 Breeding and molting coincide with food Figure 9-3

4 Simple Annual Cycles Breed Molt Survive Breed.. Resident species (Blackcapped Chickadees) Much more complex Migratory species Environmental Cues Molt

5 Circadian & Circannual Circadian Rhythms Daily cycles of light & darkness Not exactly 24hrs fluctuate with photoperiod Circannual Yearly cycles Endogenous (internal) control; possibly proximately controlled by photoperiod

6 Photoperiod Day length Pineal gland probable location of biological clock or photosensitivity Stimulate: Gonad development increase levels of sexual hormones Spring and fall molts Day length changes necessary for control of cycle recalibration

7 Migration Timing Highly precise due to biological clock Phenology of Minnesota Birds Winter (November February) Early Spring (March-April) Late Spring (May) Summer (June July) Late Summer (August) Fall (September October) Specifics (Jim Gilbert) (S. Stensaas) March 12 th Woodducks - Feb 19 th G.H.Owls April 2 nd Tree Sparrows - March 13 th Gulls May 5 th Red-eyed Vireo - April 1 st Tundra Swans May 16 th -23 rd Warblers - May 1 st Winter Wrens

8 Types of Bird Movement 1. Daily to & from roosting or foraging sites 2. Nomadic wandering irregular irruptions due to food 3. Seasonal regular movement called migration

9 A 26 day journey from Christmas Island in the Indian Ocean to forage female left on Oct 18 and returned on Nov. 14-2,485 miles!

10 Why do Animals Move? Unpredictable Resources Typical of certain fruits & seeds Patchy Environment Use separate areas for different life activities (e.g., roost & forage) Response to Photoperiod Lengthening or shortening of daylight

11 Brief Note on Breeding Seasons Temperate Regions usually related to weather/climatic conditions Tropics & Sub-tropics more likely tied to: Wet season Food production (e.g., fruit)

12 Arctic Tern 22,000 miles RT

13 -Leaves on a Sunday night & arrives on a Thursday morning hours, 3-4 days -Metabolically equal to man running 4 min miles for 80 hrs 270,000 mi/gal

14 Why Migrate? Tied to predictable, seasonal opportunities Migrants aggressively exploit temporarily favorable opportunities Benefits have to outweigh risks: Energetically expensive Increase predation risk

15 Patterns Main migration routes in North America are north-south Europe - many are east-west, but also north south This parallels the direction of main mountain ranges and rivers or waterbodies Intercontinental migration routes follow historical areas of origin

16 Migration on the Mississippi

17 Evolution of Migration 1. Most obvious - secure better climate potentially evolved with glaciation events 2. More space available a) by alternately exploiting 2 different habitats for food - more birds are able to exist, and b) more space available in north 3. Makes possible greater variety in birds diets (spatial and temporal) - able to exploit special dietary needs

18 Evolution of Migration continued 4. Exploit longer daylight hours of far north to feed young 5. Reduces predation by concentrating raising of young into one brief period during the year 6. Parasites & infectious diseases reduced in far north

19 Differential Migration Body size - homeothermism; smaller bodied birds less likely to survive winter, so they move farther south Dominance - more dominant birds gain access to limited resources; subordinates move farther south until adequate resources are obtained Arrival time - settle closer to breeding grounds to increase chance of arriving first and getting best territory; however, dominant birds that arrive later can usually drive off subordinates

20 Leapfrog Migration

21 Migration usually accomplished in a series of short, discrete flights may cover miles per day; flight not usually each day so may take 3-4 weeks to cover 2000 miles

22 Types of Migration Nocturnal migrants most songbirds, owls; initiate flight 1/2 to 1 hr after sunset - fly all night Diurnal migrants gulls, corvids, hawks, swallows - many often feed during the day while migrating avoid flying over water Diurnal and Nocturnal shorebirds, waterfowl, some passerines when flights are over water, deserts, etc

23

24 Nocturnal Migration Avoidance of predators Night air temps cooler than midday, higher relative humidity promotes convective cooling, prevents loss of body water; generation of lift in cool, dense air and energetically less costly than in warm air Horizontal winds at midnight lower than at noon birds not as likely to be driven off course Winds at night less variable in directions

25 Impacts of Weather Affect local, short term decisions to fly tailwinds - minimize energy required to fly headwinds - important - no need to try to fly even with little to moderate headwinds; energetically costly

26 Fat Deposition Completion of fat deposition in small passerines can be accomplished in 4-10 days Most species can rapidly restore depleted reserves during migration stopover habitats Amount of fat deposited is related to distances to be covered fat deposits may constitute % of live weight

27 Stopover Ecology Refuel Examples Woodlands in agricultural areas Riparian areas in the desert Coastal Areas Habitat loss = loss of essential stopovers Coastal stopovers heavily impacted

28 North Shore Stopover Study

29 North American Flyways

30 Navigation Topographic diurnal migrants coastlines, river valleys, mountain ridges; Lead lines Solar orientation evidence of orientation with the sun Stellar orientation evidence of orientation with different night skies, continuously recalibrated

31 Navigation continued Geomagnetism use of the Earth s magnetic field for orientation, continuously recalibrated Olfactory use of smell, evidence in some seabirds

32 use stars, sun, geomagnetic field and polarized light for orientation thrushes set their course using a magnetic compass, which they calibrate to the setting sun before takeoff each evening.

33 Navigation Continued Twilight Cues Polarized setting sun rays align N-S Define departure after dark Learning Young birds often get lost Learn stopovers from experience Ex: Whopping Cranes

34 Migration Help Whooping Crane Recovery Programs

35 :// es/crash-a-tale-of-twospecies/introduction/592/

36 Species is declining concern of Red Knot extinction within 5 years Conflict in US Atlantic with fisherman and their use of horseshoe crabs for bait Horseshoe crab blood $15,000/quart

37 Studying Migration Observing Trapping Tracking Radar

38 Migration Trends Case Study early 1960s Hawk Mountain migration counts show numbers of Peregrine Falcons and Bald Eagles in rapid decline Rachel Carson sites declines due to DDT in Silent Spring DDT banned in 1972

39 Observing and Counting

40 Passerine Banding

41 Trapping the Blind

42 Trapping - Nets

43 Mist-net trap of a Sharpshinned Hawk

44 Research

45 Tracking

46 Swainson s Hawks

47 Radar Ornithology

48 WSR-88D (NEXRAD) weather surveillance radar Near complete coverage of U.S. Transmits microwave signals into the atmosphere and measures returning energy reflectivity Reflectivity estimates density of targets Doppler radar at Duluth airport

49

50 Migration on the North Shore

51 Hawk Ridge, Duluth Averages 94,000 raptors Over 180,000 nonraptors Many are Passerines Corvids

52 Conservation Issues Impacts with structures Wind-turbine Development Stopover habitat Loss Climate Change

53 Birdsafe and Lights Out Minnesota Audubon Migrating birds attracted to lighted structures Results in exhaustion or collisions

54 A study of North Shore bird migration in the context of potential wind turbines Anna Peterson Jerry Niemi, Heidi Seeland, Annie Bracey, Hawk Ridge Bird Observatory Natural Resources Research Institute University of Minnesota Duluth

55 Wind Potential along North Shore

56 The Conflict (320 feet tall)

57 Diurnal Migration Study

58 Study Sites

59 Migrants (Percent of Total) Percent of migratory birds at each flight height category m to 500m Canopy to 100m Below Canopy

60 Climate Change Audubon study finds 177 North American bird species are spending winter further north Minneapolis Star Tribune 2/10/2009 When it comes to global warming, the canary in the coal mine isn't a canary at all. It's a purple finch. As the temperature across the U.S. has gotten warmer, the purple finch has been spending its winters more than 400 miles farther north than it used to. And it's not alone. aphics/ html?elr=karks: DCiUHc3E7_V_nDaycUiacyKUUr

61 Important Bird Areas Identify, monitor and conserve important sites for birds MN s first IBA: Hawk Ridge Stopover habitat