Forest birds in landscape mosaics:Forest birds in landscape mosaics:theory and empirical evidencetheory and empirical evidence

Cristián F. EstadesCristián F. Estades

Theory of Island BiogeographyTheory of Island Biogeography

((MacArthur & Wilson 1963, 1967MacArthur & Wilson 1963, 1967))

Number of species

rate

N*

colonizationextinction

Importance of:Importance of:

Island sizeIsland size

IsolationIsolation

MetapopulationsMetapopulations

((Levins 1969, 1970Levins 1969, 1970Gilpin & Hanski 1991Gilpin & Hanski 1991))

= mp(1-p) - ep= mp(1-p) - ep

p = 1 - e/mp = 1 - e/m

dpdpdtdt

ˆ̂

Ideal Free DistributionIdeal Free Distribution

((Fretwell and Lucas 1970Fretwell and Lucas 1970))

Number of competitors

Su

itab

ilit

y

G

P

Density dependentDensity dependenthabitat selectionhabitat selection

Source - sink dynamicsSource - sink dynamics

((Pulliam 1988Pulliam 1988))

Sources (R > M, E > I)Sources (R > M, E > I) subsidizesubsidize Sinks (R<M, E < I)Sinks (R<M, E < I)

40

30

20

10

1 10 100 500

.... ..

.. .. . .

Forest fragment area (ha)

p < 0.001

1.0

0.8

0.6

0.4

0.2

0.00.3 3.2 32 320 3200

Forest fragment area (ha)

Birds in Illinois Birds in Illinois forest fragmentsforest fragments((Blake & Karr 1984Blake & Karr 1984))

Incidence functionIncidence functionof Red-eyed Vireoof Red-eyed Vireo((Robbins et al. 1989Robbins et al. 1989))

Sp

ecie

s ri

chn

ess

Pro

bab

ilit

y

Birds in habitat islands - agricultural landscapesBirds in habitat islands - agricultural landscapes

024

68

101214

161820

0.1 1 10 100 10000

2

4

6

8

10

12

14

16

18

20

0.1 1 10 100 1000

Forest fragment area (ha) Forest fragment area (ha)

Birds in forest fragments in Southern ChileBirds in forest fragments in Southern ChileB

ird s

peci

es ri

chne

ss (s

pp/p

lot)

Matrix: agricultural fieldsMatrix: agricultural fields((Willson et al. 1994Willson et al. 1994))

Matrix: pine plantationsMatrix: pine plantations((Estades & Temple 1999Estades & Temple 1999))

p = 0.001 p = 0.07

d

dd

d

Extended foraging areaExtended foraging area

d: maximum distance of foraging tripd: maximum distance of foraging trip

Mosaic approachMosaic approach((Wiens 1995Wiens 1995))

General theoretical framework (but is it really workable?)General theoretical framework (but is it really workable?)

Landscape Mosaics are too IdiosyncraticLandscape Mosaics are too Idiosyncratic

Mosaic approachMosaic approach

QualitySuitabilityFitnessetc...

Food

Cover

Nest sites

Habitat mosaicHabitat mosaic

Resource mosaicResource mosaic

1. The effect of breeding-habitat patch size on bird population density

CBA

Spatial covariance between food and nest sites

- 0 +

Co

rrel

atio

n b

etw

een

bre

edin

g-h

abit

at

pat

ch s

ize

and

bir

d p

op

ula

tio

n d

ensi

ty

+

0

- C

A

B

B

B

?

?

Individual based model:Individual based model:

Goal: Explore the effect of relative distribution of food and Goal: Explore the effect of relative distribution of food and nest sites on the relationship between breeding habitat patch nest sites on the relationship between breeding habitat patch size and bird density.size and bird density.

Breeding habitat

80 x 80

Simulation model: resultsSimulation model: results

........ .... ....

Log (area)

Den

sity

.... .. .. .. .. ....

Log (area)

Den

sity

Effect of flight distanceEffect of flight distance

General modelGeneral model

Spatial covariance between food and nest sites

- 0 +

+

0

-

Edge effects Negative microclimate effects

Competitor or predator releaseR

elat

ion

ship

bet

wee

n b

reed

ing

-hab

itat

p

atch

siz

e an

d b

ird

po

pu

lati

on

den

sity

ConclusionsConclusions

The effect of breeding-habitat patch size on bird population The effect of breeding-habitat patch size on bird population density depends on the relative location of food and nesting density depends on the relative location of food and nesting sites in the landscape. Management of the matrix may sites in the landscape. Management of the matrix may affect the suitability of fragmented landscapes for breeding affect the suitability of fragmented landscapes for breeding birdsbirds

The effect of additional foraging resources in the matrix on The effect of additional foraging resources in the matrix on birds in fragmented habitat-patches depends on the birds in fragmented habitat-patches depends on the speciesspecies’’ maximum flight distance and perceived foraging maximum flight distance and perceived foraging risk.risk.

2. Spatial dynamics of bird communities in a forest landscape mosaic

The distributions of most forest bird species in the The distributions of most forest bird species in the fragmented landscape of the Maule region are not fragmented landscape of the Maule region are not adequately predicted by the size and/or isolation of forest adequately predicted by the size and/or isolation of forest patches (Estades and Temple, 1999). patches (Estades and Temple, 1999).

ProblemProblem

HypothesesHypotheses

The distribution of bird species in a landscape can be The distribution of bird species in a landscape can be modeled by looking at the distribution of food and nest sites.modeled by looking at the distribution of food and nest sites.

The distribution of birds in the landscape changes over time The distribution of birds in the landscape changes over time in accordance to the distribution of the limiting resources. in accordance to the distribution of the limiting resources. During the breeding season the best predictor of the During the breeding season the best predictor of the distribution of birds is the product of the local abundance of distribution of birds is the product of the local abundance of nest sites and food resources and during the non breeding nest sites and food resources and during the non breeding season the best predictor is the abundance of food season the best predictor is the abundance of food resources.resources.

Pine plantations 80% Pine plantations 80%

Native forests 10% Native forests 10%

Open areas 7% Open areas 7%

Study areaStudy areaMaule Region, Chile

Others 3% Others 3% 10,000 ha

Dominant species: Dominant species: Nothofagus dombeyiNothofagus dombeyi

Dominant species: Dominant species: Nothofagus glaucaNothofagus glauca

Dominant species: Dominant species: Pinus radiataPinus radiata

Tufted Tit-tyrantOpen-cup nester Understory

White-crested ElaeniaOpen-cup nester Understory and canopy

Fire-eyed DiuconOpen-cup nester Understory and canopy

Des Murs’ WiretailOpen-cup nester Understory

Thorn-tailed RayaditoCavity nester

White throated TreerunnerCavity nester

Studied species

SamplingSampling

120 point count stations120 point count stations(variable radius point counts with correction for detectability)(variable radius point counts with correction for detectability)

Field seasons: Field seasons: Winter (June) 1999Winter (June) 1999Spring (Oct-Nov) 1999Spring (Oct-Nov) 1999Summer (February) 2000Summer (February) 2000Winter (June) 2000Winter (June) 2000Spring (Oct-Nov) 2000Spring (Oct-Nov) 2000Summer (February) 2001Summer (February) 2001

.. .

.

...

..

..

..

......

.. .. ..

. .

0 50 100 200m

Food abundance

Nest sites

ModelModel

Breeding season Bird abundance = f(Nest sites * Food abundance)Non-breeding Bird abundance = f(Food abundance)Generalized linear model, negative binomial distribution

DietDiet

Analysis of droppingsAnalysis of droppings

Food abundanceFood abundance

Foliage shakingFoliage shaking

Food abundanceFood abundance

Fruit samplingFruit sampling

Aristotelia chilensisAristotelia chilensis

Nest sitesNest sites

Abundance of cavitiesAbundance of cavities Density of understoryDensity of understory

Species and Season Cavities Arthropods Cavities * Arthropods0-50 m 0-100m 0-200m 0-50 m 0-100m 0-200m 0-50 m 0-100m 0-200m

Thorn-tailedRayadito Winter 1999 . . Spring 1999 +++ +++ +++ + +++ +++ +++ Summer 2000 +++ +++ +++ . +++ +++ +++ Winter 2000 +++ +++ +++ +++ ++ +++ Spring 2000 +++ +++ +++ ++ +++ +++ +++ Summer 2001 ++ +++ +++ + ++ +++ +++

White-throatedTreerunner Winter 1999 Spring 1999 ++ + + . + +++ + + Summer 2000 + + + + ++ + . Winter 2000 Spring 2000 +++ +++ +++ +++ +++ +++ +++ +++ +++ Summer 2001 . ++ +++ + ++ +++

. : p<0.1, +: p<0.05, ++: p<0.01, +++: p<0.001. Bold: lowest AIC.

Effect of nest site abundance and arthropod biomass on the abundance of cavity nesters

Species and Season Understory Arthropods Understory * Arthropods0-50 m 0-100m 0-200m 0-50 m 0-100m 0-200m 0-50 m 0-100m 0-200m

Tufted Tit-tyrant Winter 1999 Spring 1999 ++ + ++ Summer 2000 Winter 2000 Spring 2000 + +++ +++ + +++ +++ Summer 2001 + +

Des Murs' Wiretail Winter 1999 Spring 1999 . . Summer 2000 . . Winter 2000 Spring 2000 +++ + +++ Summer 2001 +++

. : p<0.1, +: p<0.05, ++: p<0.01, +++: p<0.001. Bold: lowest AIC.

Effect of nest site abundance and arthropod biomass on the abundance of open-cup nesters

Season Arthropods Fruits Fruits * Arthropods0-50 m 0-100m 0-200m 0-50 m 0-100m 0-200m 0-50 m 0-100m 0-200m

Spring 1999 Summer 2000 Spring 2000 + + + Summer 2001 + +

. : p<0.1, +: p<0.05, ++: p<0.01, +++: p<0.001. Bold: lowest AIC.

Effect of food abundance on the abundance of White-crested Elaenias

ConclusionsConclusions

Most studied birds changed their distributions in the Most studied birds changed their distributions in the landscape between seasons and many of these changes landscape between seasons and many of these changes matched the changes in the distribution of key resources.matched the changes in the distribution of key resources.

Although factors such as competition, predation and Although factors such as competition, predation and parasitism may influence the distribution of birds in a parasitism may influence the distribution of birds in a landscape mosaic, the landscape mosaic, the “resource mosaic” model represents a parsimonious approach to understanding the distribution of birds in a patchy landscape where the matrix surrounding patches of preferred habitat is not completely useless

3. Nest success of the Thorn-tailed Rayaditoin a forest landscape mosaic

Thorn-tailed Rayaditos in the Maule region have higher Thorn-tailed Rayaditos in the Maule region have higher densities in smaller forest fragments because these birds densities in smaller forest fragments because these birds can forage in the surrounding pine plantations (Estades and can forage in the surrounding pine plantations (Estades and Temple, 1999). But is the breeding success of birds that Temple, 1999). But is the breeding success of birds that include pine plantations in their home ranges equal to the include pine plantations in their home ranges equal to the breeding success of birds that forage entirely in native breeding success of birds that forage entirely in native forest?forest?

ProblemProblem

HypothesisHypothesis

The breeding success of Thorn-tailed Rayaditos is The breeding success of Thorn-tailed Rayaditos is positively associated with the amount of native vegetation positively associated with the amount of native vegetation around the nest because of the effect of reduced food around the nest because of the effect of reduced food concentration and a potentially higher level of predation in concentration and a potentially higher level of predation in the artificial foreststhe artificial forests

50m

native vegetation: 100% 25.5% 0%

1.34 1.13 1.0 relative arthropod ab.

Upland forest Riparian forest Pine plantations

Nest success of Thorn-tailed Rayaditos

Most failures Most failures were due to were due to predationpredation

No evidence of No evidence of an effect of food an effect of food densitydensity

Thylamis elegans

Rodent

House Wren

Thylamis elegansThylamis elegans Phylodrias chammisonisPhylodrias chammisonis

Nest predatorsNest predators

Accipiter chilensisAccipiter chilensis Glaucidium nanumGlaucidium nanum

Predators of fledglings and adultsPredators of fledglings and adults

Pygarrichas albogularisPygarrichas albogularisTroglodytes aedonTroglodytes aedon

Picoides lignariusPicoides lignarius Liolaemus tenuisLiolaemus tenuis

CompetitorsCompetitors

ConclusionsConclusions

Concentration of food resources did not limit breeding Concentration of food resources did not limit breeding performance of Thorn-tailed Rayaditosperformance of Thorn-tailed Rayaditos

Small riparian forest fragments surrounded by pine Small riparian forest fragments surrounded by pine plantations not only harbor higher rayadito densities than plantations not only harbor higher rayadito densities than large upland forest patches (Estades and Temple, 1999), large upland forest patches (Estades and Temple, 1999), but they also provide a safer place to breed for this species.but they also provide a safer place to breed for this species.

Differences in breeding success between habitat types Differences in breeding success between habitat types were probably due to differences in concentration of were probably due to differences in concentration of predators and competitors and average nest height.predators and competitors and average nest height.

Nest success and nesting Nest success and nesting density of open-cup nesters density of open-cup nesters in different parts of the in different parts of the landscapelandscape

Movements of individual Movements of individual birds in the landscapebirds in the landscape

Ongoing workOngoing work

AcknowledgementsAcknowledgements

• Fondecyt (Chile) grants 1990786 and 7990027• Zoological Society of Milwaukee County• Association of Field Ornithologists• Dept. Wildlife Ecology. University of Wisconsin - Madison • School of Forest Sciences. Universidad de Chile (Santiago)• Committee: Stanley Temple, Nancy Mathews, Christine Ribic, Tony Ives, Tim Moermond• All the field assistants• Friends here and there• Paula and Josefa