migratory connectivity: science and technology for policy and conservation peter p. marra...
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Migratory Connectivity:Science and
Technology for Policy and Conservation
Peter P. Marra
Smithsonian Migratory
Bird Center
Migratory Connectivity:
The geographic linking of individuals or populations between different stages of the annual cycle, including between breeding, migration, and winter stages.
Hypothetical Species
species range
Hypothetical Species
species range
breeding
wintering
Weak ConnectivityWeak Connectivity
Birds from one breeding population disperse throughout wintering range, and
vice versa.
Hypothetical SpeciesPopulation
Connections
Hypothetical SpeciesPopulation
Connections
Strong Strong ConnectivityConnectivity
One-to-one connections
between summer and winter
populations
Hypothetical SpeciesPopulation
Connections
Hypothetical SpeciesPopulation
Connections
For most species,For most species, we don’t know the we don’t know the
strength of strength of migratory migratory
connectivityconnectivity
Hypothetical SpeciesHypothetical Species
JF
M
A
M
JJ
A
S
O
N
D
breedingwinteringmigrationmolt
Periods of the annual cycle are
inextricably linked
Why Study Migratory Connectivity?Why Study Migratory Connectivity?
ConservationPopulation Vulnerability
Population VulnerabilityPopulation Vulnerability
Why Study Migratory Connectivity?Why Study Migratory Connectivity?
Population Abundance
Ecology, Behavior, EvolutionDemography, Mating SystemsLife History Strategies
Human HealthSpread of Invasive Disease
(HPAI,WNV)
• Conservation• Population Vulnerability
Why Study Migratory Connectivity?Why Study Migratory Connectivity?
Population Abundance
• Conservation• Population Vulnerability
Seasonal Interactions
• Events in one period of the annual cycle influence events in subsequent periods.
2. Individual-level (carry-over effects)
1. Population-level (density effects)
(Sutherland 1996)
Seasonal Interaction Model: Population-level
Total Population Size
Per
Cap
ita
Rat
e
E
Winter Mortality
Net BreedingOutput
(Sutherland 1996)
Seasonal Interaction Model: Population-level
Total Population Size
Per
Cap
ita
Rat
e
E
Winter Mortality
Net BreedingOutput
E1
(Sutherland 1996)
Seasonal Interaction ModelPopulation-level
• Population change depends on the relative strengths of density dependence between winter and summer.
• The consequences of habitat loss is greatest for the season in which there is the strongest density-dependence.
• For Oystercatchers, winter was the most limiting season.
Total Population Size
Per
Cap
ita
Rat
e
E
Winter Mortality
Net BreedingOutput
E1E2
Few examples of population-level seasonal interactions exist.
• Weak understanding of migratory connectivity
• Few estimates of DD from non-breeding season
• Little research during the non-breeding season
Individual-level:Carry-over effectsIndividual-level:
Carry-over effects
Study Design
• 2002 - 2006 • Font Hill Nature Reserve
• American redstart
• 3 mangrove, 3 scrub sites
• Range in size 1 - 5 ha
Performance is driven by habitat occupancy
Black mangrove Second-growth scrub
Physical condition
Spring departure date
Annual Survival
maintain
early
high
decline
late
low
Hypothesis:Environmental conditions on
wintering grounds influence reproductive success via carry-over effects
Arrival dynamics
Winter habitat(wet / dry)
Breeding territory quality
Fecundity
Hypothesis:Environmental conditions on
wintering grounds influence reproductive success via carry-over effects
Moisture Gradient WETDRY
C3
C4
Enriched 13C Depleted 13C
Wet Lowland Forest
Black Mangrove Forest
Second-growth Forest
13C
(m
ean
+/-
se)
Carbon Isotope Signatures from American Redstart
N = 5
N = 10
N = 34
N = 8
N = 24
-25.0
-24.5
-24.0
-23.5
-23.0
-22.5
-22.0
-21.5
-21.0
Jamaica Honduras
Prediction:
1. have lower levels of 13C relative to redstarts arriving later.
American redstarts arriving early will
2. be in better physical condition than those arriving later.
13C and arrival date in ASY males
R2 = 0.38, p < 0.0001n=35
R2 = 0.34, p = 0.0004n = 32
2001 2002
0
5
10
15
20
25
Arr
ival
dat
e
-24 -23.5 -23 -22.5 -22 -21.5 -21
13C
5
10
15
20
25
Arr
ival
dat
e-24 -23.5 -23 -22.5 -22 -21.5
13C
Arrival Date (May)
Mas
s C
orr
ecte
d f
or
Bo
dy
Siz
e
Physical Condition vs. Arrival Date
P = 0.02 r = -0.52
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
12 14 16 18 20 22 24 26 28 30
5
4
3
wet forest mangrove scrub
Num
ber
of Y
oung
Fle
dged
females
ASY males
Winter Habitat Origin
wet dry
citrus
Predicted changes in number of young fledged
Summary• Winter habitat occupancy drives patterns of
reproductive success on the breeding grounds
• Our other work suggests:1) Winter conditions drive mortality during
migration
2) Winter habitat drives natal dispersal
3) Reproductive costs influence feather color and quality
Where are we in tracking wide-ranging animals?
• Transmitters (radio & satellite )
• Isotopes (individual & population)
1. Intrinsic• Banding (capture-recapture)
2. Extrinsic
• Microbes and Parasites
• Molecular Markers
• Trace elements
Band Recovery Data - Purple Martins
Atlantic Ocean
NJ
DE
PA
NY
MD
Atlantic City
Philadelphia
Trenton
100 km
Delaware Bay
5 13
1
3
1
4(10)
3(10)
34
6
7
9
2
3
6
7 (10)
4
3
4
5
4
12
3
International Space Station
Birds in Space
Copyright ©2006 by the National Academy of Sciences
Shaffer, Scott A. et al. (2006) PNAS 103, 12799-12802
Sooty Shearwater Migrations
Isotopes
Stable-hydrogen isotopes
• Stable-hydrogen isotopes vary with latitude
• Feathers sampled in the nonbreeding period reflect origins in the previous summer
-45
-95
-75-55
-50
-125-115
-165
-135
-135-165
-165
-125-115
-95
-75
-55
-50
-45
60°
50°
60°
50°
40°
40°
30°
30°
20°
20°
10°
10°
H isotopes and banding data
American redstartSetophaga ruticilla
Summary
• We still have no clear solution for measuring connectivity…..but we are getting there
• The best approach will probably be to integrate multiple markers
Conclusions
• Seasonal interactions and carry- over effects influence the ecology and evolution of species
• Investment in technological research is critical
• Understanding migratory connectivity is critical for conservation
• International cooperation through treaties
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