Habitat selection at fine spatial scales: How consistent is - - PowerPoint PPT Presentation

Michael A. Patten, Brenda D. Smith-Patten, and Jeff F. Kelly University of Oklahoma, Norman, Oklahoma, USA

Habitat selection at fine spatial scales:

How consistent is microclimate between the breeding and wintering grounds of Neotropical migrant passerines?

Correlates of extinction risk

Patten & Smith-Patten (2011, Conservation Biology 25:1203–1211)

Persistence or extirpation?

A key potential reason is altered microclimate; e.g.:

• higher temperature
• stronger wind
• increased light
• lower humidity (i.e.,

desiccation)

Mechanisms?

Patten & Smith-Patten (2011, Conservation Biology 25:1203–1211)

La Milpa Field Station, Belize Las Cruces Biological Station, Costa Rica (n = 129 plots) (n = 103 plots)

Residents

mini weather station

Methods

light meter ambient temperature, relative humidity, heat index, wind speed, light intensity

Canonical Correspondence Analysis

 A multivariate ordination technique.

 orders sites along environmental gradients  like other ordinations in the CA family, also orders

species across the gradient

 A type of direct ordination.

 environmental variables are included in the analysis  in the case of CCA, environmental variables are used in

an associated multiple regression to constrain the algorithm that orders the sites (and species)

 Produces a biplot that shows how the environmental

variables relate to the ordering of sites (or species).

Drivers of Assemblage Structure

Canonical Variate I

• 1

1 2 3

Canonical Variate II

• 1

1

VPD light temp canopy wind Las Cruces Canonical Variate I

• 1

1 2

Canonical Variate II

• 2
• 1

1

VPD light temp canopy wind La Milpa

Patten & Smith-Patten (2012, Biological Conservation 155:85–93)

Light Mattered Most . . .

Patten & Smith-Patten (2012, Biological Conservation 155:85–93)

“We emphasize the need to consider how individuals move and interact with their environment throughout their annual cycle and over hemispheric scales.” – Renfrew et al. (2013, Diversity and Distributions 19:in press)

What about Migrants?

Ouachita National Forest, Oklahoma (La Milpa, n = 86 plots; Hill Bank, n = 16 plots) (n = 28 plots)

Migrants

Rio Bravo Conservation and Management Area, Belize

Focal Species

Kentucky Warbler

Geothlypis formosa

Black-and-white Warbler

Mniotilta varia

White-eyed Vireo

Vireo griseus

Hooded Warbler

Setophaga citrina

Red-eyed Vireo

Vireo olivaceus

• Calculate means of microclimate variables
• wind speed (m/s)
• ambient temperature (ºC)
• vapor pressure density (humidity)
• canopy cover (%)
• light penetration (kLux)
• heat index – although highly correlated with temperature . . .

for occupied plots vs. available plots on both the breeding grounds and the wintering grounds.

• Calculate ratios of occupied to available for each variable

(ratios within ±0.25 of 1.0 suggest no effect).

• Compare ratios for breeding and wintering grounds.

Analysis

Results

canopy temperature VPD heat index wind light available 61.4 22.2 0.55 23.6 0.37 2.21

• ccupied

49.2 24.2 0.68 26.5 0.81 3.37 ratio 0.80 1.09 1.23 1.12 2.17 1.53 White-eyed Vireo

Vireo griseus

canopy temperature VPD heat index wind light available 67.1 25.3 1.34 26.0 0.34 3.86

• ccupied

69.1 25.5 1.50 26.1 0.58 5.23 ratio 1.03 1.01 1.12 1.01 1.68 1.35

wintering grounds breeding grounds

Results

species VPD wind light winter breed winter breed winter breed White-eyed Vireo 2.17 1.68 1.53 1.35 Black-and-white Warbler 0.58 0.57 0.58 Kentucky Warbler 0.74 0.70 0.45 0.25 0.48 Red-eyed Vireo 0.40 0.50 0.62 Hooded Warbler 1.36 1.34

No signal for canopy cover, ambient temperature, or heat index.

Results

species VPD wind light winter breed winter breed winter breed White-eyed Vireo 2.17 1.68 1.53 1.35 Black-and-white Warbler 0.58 0.57 0.58 Kentucky Warbler 0.74 0.70 0.45 0.25 0.48 Red-eyed Vireo 0.40 0.50 0.62 Hooded Warbler 1.36 1.34 1.14

No signal for canopy cover, ambient temperature, or heat index.

• Microclimate attributes are important aspects of habitat

selection.

• The extent of light penetration is the key microclimate

variable.

• Boreal migrants occupy similar light environments on their

wintering grounds as on the breeding grounds.

• Preference for high or low light environments varies across

species.

• White-eyed Vireo – high (forages in lower strata)
• Black-and-white Warbler – low (mid-levels, but near trunks)
• Kentucky Warbler – very low (largely terrestrial)

Summary

Preservation or restoration of the light environment ought to be a major goal of conservation efforts for boreal migrants (and tropical resident) species of birds.

Conclusion