Talk given at Wildlife Institute of India

1. Avian Migration Systems:
An Ecological Niche
Perspective
with Yoshinori Nakazawa, Adolfo
Navarro, Enrique Martinez-Meyer

3. Migration Systems I
Evolution of migration envisioned as follows:
 Original sedentary (tropical) ancestor
 Local movements to track seasonally varying resources
 ‘Hard-wiring’ of seasonal movements
 Extension to longer-distance movements
Ecological studies have documented examples of
each imagined stage
Not traditionally viewed in a phylogenetic context …
historical perspective on evolutionary process has
been lacking
Ecological niche modeling can illuminate the details
of the process …

4. Migration Systems II
Species obey consistent ecological ‘rules’ in
their geographic distributions …
How do these ecological rules vary between
seasonal distributional areas … ?
 Niche-following – a species follows a consistent
set of ecological conditions from one season to
the next
 Niche-switching – a species breeds under one
set of ecological circumstances, but overwinters
in another set of conditions
Phylogenetic distribution of this potential
diversity and its implications?

5. Niche-following example (Vireo belli)
Model based on points from
Breeding Winter
Seasonpredicted
WinterBreeding

6. Niche-switching example (Dendroica magnolia)
Model based on points from
Breeding Winter
Seasonpredicted
WinterBreeding

7. Distribution of Interpredictivity Values
0
5
10
15
20
25
30
35
0-0.1 0.1-0.2 0.2-0.3 0.3-0.4 0.4-0.5 0.5-0.6 0.6-0.7 0.7-0.8 0.8-0.9 0.9-1.0
Significance level (P)
Frequency
Niche switchers
Niche followers

8. Phylogenetic
and Ecological
Distribution
of Niche-
following
Behavior
Species Breeding Wintering
Dendroica aestiva
Dendroica auduboni
Dendroica coronata
Dendroica dominica
Dendroica magnolia
Dendroica nigrescens
Dendroica occidentalis
Dendroica townsendi
Dendroica virens
Spizella atrogularis
Spizella breweri
Spizella pallida
Spizella passerina
Vermivora celata
Vermivora peregrina
Vermivora ruficapilla
Vireo bellii
Vireo cassinii
Vireo gilvus
Vireo griseus
Vireo huttoni
Nakazawa et al. 2004, Auk
Taiga belt species

9. Monarch Butterfly
Migration and Seasonal
Niches
with Rebecca V. Smith and Karen
Oberhauser

13. Monarchs

14. Citizen Science Project

15. MLMP Sample Sites

16. Monthly Occurrence Data
• tally monthly occurrences
• model month-specific ecological niches
• predict all other months from each month
• average predictions from all other months to each month
• test prediction for each month with (independent) occurrence data from that month

17. Seasonal Shifts – Hot & Humid

18. Predictability of Seasonal Shifts

19. Winter – December-February

20. Wintering Monarchs?
Note that the
butterflies are
not where their
niche is!

21. Niche Dimensions
0
20
40
60
80
100
120
140
160
-300 -200 -100 0 100 200 300 400
Temperature (C x 10)
Precipitation(cmx10)
0
20
40
60
80
100
120
140
160
-300 -200 -100 0 100 200 300 400
Temperature (C x 10)
Precipitation(cmx10)
0
20
40
60
80
100
120
140
160
-300 -200 -100 0 100 200 300 400
Temperature (C x 10)
Precipitation(cmx10)

22. Monarch Conclusions
Monarchs are both niche-followers and niche-
switchers through the course of the year
The two niches that monarchs use during the
year are contrasting – one for breeding and
the other for overwinter survival
Climate change will affect both, but in very
different ways…

23. General Conclusions
Migratory systems are diverse in ways that the field did not
anticipate—’migratory’ species can have very different
characteristics in terms of seasonal ecology
This diversity appears to have phylogenetic components—
that is, some clades tend to be niche-switchers (e.g.,
Dendroica), and others to be niche-followers (e.g., Vireo)—
but broad phylogenetic studies are just now beginning
This diversity appears to have ecological / geographic /
historical components—e.g., taiga species
Breeding distributions appear to be derived relative to the
winter distributions, at least in the clade tested to date
Niche-switching appears to be derived relative to niche-
following, thus constituting a further step in the evolution of
complex migratory behavior
 Sedentary  local tracking  seasonal local movements  long-
distance migration (niche-following)  long-distance migration (niche-
switching)
Further exploration and testing are needed…