Transcript Habitat Selection

Species-of-the-Day
Wood Duck (Aix sponsa)
Brink of Extinction
By early 1900’s, culminative effects of:
1) wetland drainage (ag. expansion)
2) deforestation
3) overhunting
Habitat
• Wooded swamps &
river bottomlands
• Natural tree cavities for
nesting (cypress,
sycamore, silver maple,
black ash)
• Home range changes
with flooding events
Food
* In water <18”, feed on:
- seeds of trees (e.g.,
acorns)
- also field grains
* Young = aquatic
insects
Reproduction
Pairing in late Oct into
spring (Mar-July nest)
Clutch size = 6-10 eggs
Behavior
- Dump nests (up to 30+
eggs in 1 nest) = “egg
dumping” behavior =
intraspecific brood
parasitism
- may decrease hatch rates
to 10%
Factors Determining Patterns of
Habitat Use
• Competition
• Predation
Concept of Habitat Selection
• Wildlife perceiving correct configuration of
habitat needed for survival – differences based
on age/experience/chance? – hierarchy to
decision process
• Niche concept (time/place/functional role) &
habitat selection
• For example, in open habitats, bats use lowfrequency / long-distance calls (ultrasound)
while foraging
• Whereas, bats in closed canopy settings =
constant/high frequency = detect wing beats
Hutchison’s n-dimensional hypervolume
Concept of Habitat Selection
• Hutchison = n-dimensional hypervolume as
explanation of the niche
• Fundamental vs. Realized Niche
Species 1
Species 2
Testing the Hutchinsonian Niche
Concept of Habitat Selection
• James – work with birds in
Arkansas…quantified habitat relationships
• How do birds select habitat?
• niche gestalt : each species has characteristic
perceptual world…responds to that world as
organized whole … search image concept
• How do we (as wildlife biologists) “see”
through the eyes of wildlife species?
Wildlife Habitat Ecology & Mgt
• Habitat from an evolutionary perspective
• Species distribution relative to habitat dist’n
• Climatic events
• Pleistocene Epoch & dist’n of modern species
habitat interspersion –
Leopold’s Law of Interspersion
Habitat Fragmentation
1) gap formation
2) decrease patch
size
3) increase isolation
4) increase edge
5) conversion of
matrix
Concepts
• Habitat = species-specific resources
available (relative quality)
• Habitat Use = manner in which species
use resources
• Habitat Selection = hierarchical decision
process (innate & learned) of what
habitats to use
• Habitat Preference = based on selection
of habitat, which are used more than
others (preferred vs. avoided)
Concepts
• Habitat Availability = accessibility of
resources
• Habitat Quality = positive relation with
fitness (not just density)
• Critical Habitat = resources essential to
the species….ESA designation….How is
it determined?
1st order – innate?
2nd order –decisions
3rd &4th order
–decisions
Scale Dependence
of Habitat Selection
1st Order
2nd Order
3rd Order
4th Order
Macrohabitat
vs.
Microhabitat
Need for Multiscale Analysis
• e.g., Australian leadbeater’s possum
• landscape vs. local scales
Hierarchy Theory
Constraints
(significance)
Level of Focus
(level of interest)
Components
(explanation)
Community
Population
Individual
Constraints
Why do long-tailed
weasels select forest patches
and fencerows
in fragmented landscapes?
Components
Guild Concept
• guild = group of species that exploit the
same class of resources in similar way
• community guild = no taxonomic
restrictions; guild members chosen
based on investigator-defined
resources
• assemblage guild = guild members
based on taxonomic relations
Models of Habitat Relationships
• Model (assess) habitat for wildlife
species, e.g., USFWS
• Habitat Suitability Index (HSI)
models
- include top 3 environmental
variables related to a species’
presence, distribution, &
abundance
HSI = (V1 x V2 x V3)1/3 = 0 to 1
• Yellow
Warbler HSI
for different
forest
conditions
HSI models
• useful for representing possible major
habitat factors
• true value as hypotheses
• Do not provide information on:
- population size or trend
- behavioral responses
• single-species approach
Species-of-the-Day
Kirtland’s warbler (Dendroica kirtlandii)
Habitat
NE Michigan jack pine
forests
- Nesting habitat = 2-6 m
(~5-20 ft) tall young
jack pines (<15 yrs) =
very dense stands
- Large forest stands =
100+ ha (200+ A)
2001 = 1,085 singing males = highest count
since 1951
Food
Insectivores &
herbivores
Reproduction
~May, late May = 5 eggs
i.p. = 13-16 days
Behavior
- Migrate to Bahamas
- Return to MI early to
mid May (males 1st)
- Influence of brownheaded cowbirds (nest
parasitism)
ecotones, coverts, edges
The “Edge Effect”
Core Areas – Interior
Habitat
“Not all habitat
patches are the
same”
• habitat-interior
species
• Area-sensitive
species
Countering Edge Effects &
Habitat Fragmentation
• Increase edge complexity
Countering Edge Effects &
Habitat Fragmentation
• Increase edge complexity
• Develop connective corridors
Linking Core Areas
& Refuges
Multiple-Use Module
(MUM) Network
• Refuges (nodes)
connected by
corridors
Roads: Formation of Barriers in Landscapes
Species-of-the-Day
grizzly bear (Ursus arctos)
Habitat
Mississippi R to Pacific
(plains, forests,
mountains, wetlands,
beaches)…
Today, (US, lower 48)
Montana
Wyoming
Idaho
Washington
1985 – Interagency Grizzly Bear Committee
Food
Omnivores – up to 90%
plant matter
* Seasonality
Reproduction
~mid May to early July
litter size = up to 2
*delayed implantation
Behavior
Hibernation (Oct-May)