Waterbird habitat use of terraced ponds in coastal Louisiana

1
Waterbird habitat use of terraced ponds in
coastal Louisiana
J. OConnell (joconn4_at_lsu.edu), and J.A Nyman
(jnyman_at_lsu.edu) School of Renewable Natural
Resources Louisiana State University
2
Coastal Louisiana as waterbird habitat

• gt 25 of continental population for ten species
  of wading and seabirds
• More nesting colonies for wading and seabirds
  than any other state in Southeast
• 20 of continental population of wintering
  waterfowl
• No previous studies have examined the effects of
  terracing on waterbirds

3
Study objectives

• Compare terraced vs. unterraced ponds as habitat
  for waterbirds
• Evaluate habitat quality using
• Waterbird diversity abundance
• Submerged aquatic vegetation biomass
• Nekton diversity and biomass
• Water quality

4
Methods

• Sites 3 sets of paired ponds
• Pairs
• 1 terraced pond
• 1 unterraced
• Similar size
• Brackish marsh dominated by Spatina patens.
• No major sediment sources.

5
Louisianas Chenier Plain
Texas
Calcasieu Lake
A
Vermillion Bay
B
C
Gulf of Mexico
A Sweet Lake site B Rockefeller SWR site C
Vermillion sites
6
Sweet Lake site
7
Rockefeller SWR site
Terraced Pond
LA Hwy. 82
Unterraced Pond
Gulf of Mexico
Deep Lake
8
Vermillion site
Pecan Island
LA Hwy. 82
Terraced Pond
Unterraced Pond
9
Methods

• Three study methods
• Pilot study with photosensitive cameras
• Pre-hurricane with long survey periods and live
  observers
• Post-hurricane with live observers and short
  survey periods

10
Surveys using cameras

• Simultaneous observation of all ponds
• Light sensitive
• Record for 2 hrs at sunrise and sunset
• Record for 6 days
• Digitized/analyzed in lab
• Bird observations taken off video

11
Preliminary results cameras

• Not an effective tool

12
Pre-hurricane survey using live observers

• Terraced and unterraced ponds watched
  simultaneously
• Survey for 90 min at sunrise following a 15 in
  settling period
• Watch 12 hectare plots
• Surveyed once a month from February - September
  2005

13
Pre-hurricane methods

• Score at 15 min intervals
• Species diversity
• Species abundace
• Individual behavior

• Microhabitat
• Qualitative distance from cover

14
Environment variables

• Correlate bird use with environmental variables
• Wind speed
• Air temperature
• Salinity
• Water temperature
• Turbidity
• Water depth

15
Food availability

• Nekton and SAV abundance
• Close to edge
• gt 50 m from edge
• 1m2 throw trap used
• Above-ground biomass for SAV collected
• Nekton cleared after 5 empty passes

16
Preliminary results bird use of terraced vs.
unterraced ponds
17
Species richness in terraced vs. unterraced ponds
18
Preliminary results live observers

• Grouped bird species into guilds by foraging
  style
• Diving foragers (grebes, diving ducks,
  cormorants, American White Pelican)
• Wading birds (herons, egrets, ibis, and roseate
  spoonbill)
• Probers and surface arthropod gleaners
  (sandpipers, plovers, American avocet,
  black-necked stilt, and rails)
• Aerial foragers (terns, gulls, and belted
  kingfisher)
• Dabblers (dabbling ducks, common moorhen,
  American coots, and purple gallinule)

19
Diver use of terraced vs. unterraced ponds
20
Wader use of terraced vs. unterraced ponds
21
Aerial forager use of terraced vs unterraced ponds
22
Post-hurricane surveys with live observers

• Arrive via airboat or go-devil.
• Minimize disturbance to pond when possible.
• Survey two plots per pond each survey.
• Two observers for increased accuracy.

• Record all birds on or flushed from plot during a
  ten-minute interval.
• Surveyed from December 2005-April 2006, multiple
  times per month.
• Water quality data collected.
• Fish and SAV data not collected.

23
Post-hurricane survey results

• One more field survey left.
• Data still yet to be compiled.

24
Conclusions

• Pilot study showed cameras not effective over
  large areas.
• Pre-hurricane study
• Potential to show environmental relationships
  influencing bird abundance and diversity.
• Further analysis needed.
• Post-hurricane study is ongoing data will be
  compiled soon.

25
Any questions?
26
SAV biomass at edge in terraced vs unterraced
ponds
27
Turbidity at marsh edge in terraced vs.
unterraced ponds

• p 0.0686