Transcript Monitoring Approaches

Ecological Methodology
LEC-04
Althoff
Monitoring Approaches – Part I
Monitoring Approaches
• Complete census (total count of individuals)
• Survey—sample a portion of the species
“suspected” distribution (to get popn estimate)
a) distance sampling
b) mark-recapture
c) drives (ex. deer), aerial photos (ex.
waterfowl, caribou)
• Indirect: “signs” of presence, DNA analysis of
droppings, etc.
• New & Old:
a)
b)
Checklist
• Oldest technique in the book!
• As conservation biologist become more
sophisticated with “statistical” approaches,
checklist were pretty much dropped as having
value:
a) considered anecdotal
b) lacked quantitative content
• But…many still keep field notes and amateur
groups routinely keep records of sightings
(especially birders)
Checklist…advantages
• Low cost
• Minimal training required to compile assuming:
a) accurate ID of species
b) accurate recording of species, location, etc.
• Broad coverage…many areas searched that may
not get covered with formal, “scientifically sound”
sampling
• Compatible with carrying on other activities
including hiking, birding, patrols, etc.
Checklist… some biases/disadvantages
• Hot spots likely to receive more attention that
places that individuals suspect does not offer
much in the way of viewing wildlife
• “Glamour” species more likely to be detected
during routine observations than those that are
not as colorful, nor perceived as “exciting”
• My hit “peaks” of activity…not full range of activity
• Indirect observations (i.e, droppings, nests,
tracks, etc.) often not recorded
Checklist can provide…
•
•
•
•
•
Long-term data sets
Phenology info
Population trends (coarse)
Species richness estimates
Biogeographic patterns
Given the alternative of collecting no information,
this approach should be considered as another
“piece” to the monitoring effort.
Results from a Study of Bird Checklist
Droege, S., A.Cyr, and J. Larivee. 1998. Checklists: an under-used tool for the
inventory and monitoring of plants and animals. Conservation Biology 12(5):1134-1134
• Compared checklist from Quebec program and
determined they provided reliable info on
conservation, management, and ecology of many
bird species.
• Small scale changes in a species’ population
number are likely to go undetected…but ________
____________________________________
• The more years of data from checklist-type
reporting the more reliable the overall trends tend to
be…and, in some cases, “adjustment” factors may
be determined that correlate with more rigorous
surveys conducted on a smaller scale
Presence/Absence As A Metric
• Obtaining population demographic data is often
extremely costly…and impractical for a large
number of species.
• Recent research into presence/absence surveys
indicates that, using models and determining
____________________, this approach may serve
as a more cost-effective way to monitoring some
species
• Additional research is needed
Presence/Absence—some basics
• Single time, once-a-year surveys are of ________
value if no pilot study conducted to determine
detection probabilities
• The more surveys that are done in a “reasonable”
time frame, the greater the ___________ in a
determination of “presence” or “absence”
• Repeated surveys are required….example
Site 1: 0 1 0 1 1
Site 2: 1 0 0 0 0
Site 3: 0 0 0 0 0
Site 4: 0 0 0 1 0
Site 5: 0 0 1 1 0
Survey No.
1
2
3
4
5
Presence/Absence
Site 1:
Site 2:
Site 3:
Site 4:
Site 5:
0
1
0
0
0
1
0
0
0
0
0
0
0
0
1
1
0
0
1
1
1
0
0
0
0
Survey No.
1
2
3
4
5
surveys to detect
survey to detect
surveys, not detected…”absent”
surveys to detect
surveys to detect
Presence/Absence
Site 1:
Site 2:
Site 3:
Site 4:
Site 5:
0
1
0
0
0
1
0
0
0
0
0
0
0
0
1
1
0
0
1
1
1
0
0
0
0
Survey No.
1
2
3
4
5
2 surveys to detect
1 survey to detect
5 surveys, not detected…”absent”
4 surveys to detect
3 surveys to detect
After 5 surveys,
After 4 surveys,
After 3 surveys,
After 2 surveys,
After 1 survey,
of sites
of sites
of sites
of sites
of sites, species “__________”
At what point do you have the most
confidence in your data to conclude that the
species is present or absent from the area?
• More easily the species is to ‘see’ the few surveys
you would need
• The better the “timing” to detect a species, the fewer
the surveys you would need
• The more locations (plots) you sample and repeat
visits to survey, the more likely you are to improve
the confidence in the probability of detection
Some key references…
Ruggerio, L. and D. Pearson. 2000. Presence/absence as a metric for monitoring
vertebrate populations. USDA Forest Service Proceedings RMRS- P-17. Pages 41-44.
Royle, J.A. and J. D. Nichols. 2003. Estimating abundance from repeated presenceabsence data or point counts. Ecology 84(3):777-790.
MacKenzie, D.I., J.D. Nichols, J.A. Royle, K.H. Pollock, L.L. Bailey, and J.E. Hines. 2006.
Occupancy estimation and modeling: inferring patterns and dynamics of species
occurrence. Elsevier Academic Press, New York, New York.
• Presence-absence surveys and determination of
probability of detection will…
a) likely to continue to receive more attention/use
b) be more cost effective
c) likely be as accurate for many species, with
“correction factors” as intensive popn
estimation techniques