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Avian Migration Systems:An Ecological Niche
Perspective
with Yoshinori Nakazawa, Adolfo Navarro, Enrique Martinez-Meyer
Migration Systems IEvolution 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 stageNot traditionally viewed in a phylogenetic context … historical perspective on evolutionary process has been lackingEcological niche modeling can illuminate the details of the process …
Migration Systems IISpecies 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?
Niche-following example (Vireo belli)Model based on points from
Breeding Winter
Sea
son
pred
icte
dW
inte
r
B
reed
ing
Niche-switching example (Dendroica magnolia)Model based on points from
Breeding Winter
Sea
son
pred
icte
dW
inte
r
B
reed
ing
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)
Fre
quen
cy
Niche switchers
Niche followers
Phylogenetic and Ecological Distributionof Niche-following Behavior
Species Breeding WinteringDendroica aestivaDendroica auduboniDendroica coronataDendroica dominicaDendroica magnoliaDendroica nigrescensDendroica occidentalisDendroica townsendiDendroica virens
Spizella atrogularisSpizella breweriSpizella pallidaSpizella passerina
Vermivora celataVermivora peregrinaVermivora ruficapilla
Vireo belliiVireo cassiniiVireo gilvusVireo griseusVireo huttoni
Nakazawa et al. 2004, Auk
Taiga belt species
Monarch Butterfly Migration and Seasonal
Niches
with Rebecca V. Smith and Karen Oberhauser
Monarchs
Citizen Science Project
MLMP Sample Sites
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
Seasonal Shifts – Hot & Humid
Predictability of Seasonal Shifts
Winter – December-February
Wintering Monarchs?
Note that the butterflies are
not where their niche is!
Niche Dimensions
0
20
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-300 -200 -100 0 100 200 300 400
Temperature (C x 10)
Prec
ipita
tion
(cm
x 1
0)
0
20
40
60
80
100
120
140
160
-300 -200 -100 0 100 200 300 400
Temperature (C x 10)
Prec
ipita
tion
(cm
x 1
0)
0
20
40
60
80
100
120
140
160
-300 -200 -100 0 100 200 300 400
Temperature (C x 10)
Prec
ipita
tion
(cm
x 1
0)
Monarch Conclusions
Monarchs are both niche-followers and niche-switchers through the course of the yearThe two niches that monarchs use during the year are contrasting – one for breeding and the other for overwinter survivalClimate change will affect both, but in very different ways…
General ConclusionsMigratory systems are diverse in ways that the field did not anticipate—’migratory’ species can have very different characteristics in terms of seasonal ecologyThis 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 beginningThis diversity appears to have ecological / geographic / historical components—e.g., taiga speciesBreeding distributions appear to be derived relative to the winter distributions, at least in the clade tested to dateNiche-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…
