Zoology Session 1:303:00, 27 Sep 05

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Zoology Session130-300, 27 Sep 05

• Issues with EO Specs
• Assessing viability A proposed framework for EO
  Rank Specs for animals
• Mapping Animal EOs

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Issues with EO Specs and EO Rank Specs for Animals

• East Region Heritage Conference
• 27 September 2005
• 130-300 pm

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Definition of an Occurrence
http//www.natureserve.org/prodServices/eodata.jsp

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What is an Occurrence? (cont)

• For species, a principal EO conceptually
  represents the full occupied habitat (or
  previously occupied habitat) that contributes, or
  potentially contributes, to the persistence of
  the species at that location. In so far as
  possible and practical, a principal EO should
  correspond to a population or metapopulation.

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The Purpose of EO Specs

• EO specifications are used to delineate and
  differentiate EOs. In other words, EO
  specifications define precisely what evidence
  constitutes a valid EO (i.e., the minimum size,
  quality, or persistence required), and what
  distances or factors separate one principal EO
  from another.

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Why should we care?Delineation of EOs
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Why should we care?Ranking of EOs
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Some species have their own occurrence
specifications, but many species are covered by
occurrence specifications for a group of
taxonomically related and/or ecologically similar
species (a specs group).
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Minimum occurrence criteria for ambystomatid
salamanders
Occurrences are based on evidence of historical
presence, or current and likely recurring
presence, at a given location. Such evidence
minimally includes collection or reliable
observation and documentation of one or more
individuals (including larvae or eggs) in or near
appropriate habitat where the species is presumed
to be established and breeding.
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Separation Distance and EO Mapping

• Separation distance does not affect how occupied
  patches of habitat (source features) are mapped,
  but it does alter how these patches are allocated
  among occurrences.
• Occurrence boundary delineation is a process that
  is independent of separation distance

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Separation Distances

• Separation distances should yield occurrences
  that are, for all practical purposes,
  demographically independent.
• But there is no single, strictly correct measure
  for identifying independent populations or
  metapopulations demographic and genetic
  connections among populations form a continuum
  rather than discrete categories.
• And there is substantial ecogeographic and
  temporal variation in average or modal movement
  characteristics of a species.

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Separation Distances (cont)

• Consequently, in element occurrence
  specifications, certain somewhat standardized
  separation distances (e.g., 5, 10, 15, 20 km)
  have been adopted.
• Although these separation distances are
  necessarily fairly arbitrary, they do generally
  attempt to reflect mobility similarities and
  differences among species or groups of species.

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Minimum Suitable-Habitat Separation Distance

• For most species, occupied locations separated by
  short distances of suitable habitat not known to
  be occupied generally do not represent discrete
  populations usually the intervening area is
  occupied (if not in the short-term then usually
  over a period of several years), or at least it
  is not a significant discontinuity between
  populations. Thus the minimum suitable-habitat
  separation distance should not be too small.

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Minimum Suitable-Habitat Separation Distance

• Accordingly, the minimum suitable-habitat
  separation distance is 3-5 kilometers for most
  species and groups, and 1 or 2 kilometers for
  only the most sedentary ones. These values,
  though necessarily arbitrary, are intended to
  reduce the incidence of inadvertent splitting of
  populations and metapopulations into multiple
  occurrences.

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Minimum Suitable-Habitat Separation Distance

• In the case of birds and other highly mobile
  species, separation distances must be much
  smaller than movements would indicate such that
  occurrences are of practical size for
  conservation purposes (such occurrences do not
  attempt to represent populations or
  metapopulations).

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Overriding Separation Criteria

• Separation distances should be overridden only
  when professional consensus indicates that it is
  more biologically appropriate to do so than to
  establish multiple occurrences.
• As a general rule, patches of occupied suitable
  habitat that are more than approximately 1.5
  times the separation distance from the nearest
  occupied patch should not be recorded as parts of
  the same occurrence.
• However, in vast, relatively uniform landscape
  units for which survey data are sparse, the
  nominal separation distance may be increased even
  further, if it is more biologically reasonable to
  do so than to establish multiple occurrences

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Alternative Separation Procedures

• Occurrence specifications may provide separation
  distance values for more than two categories of
  habitat.
• EO Specs may employ a qualitative method (e.g.,
  based on hydrographic units or population
  migration patterns) rather than numerical
  distances for distinguishing occurrences.
• For some highly mobile, occurrence-tracked
  species for which locational data are typically
  recorded as points or tiny polygons, EO
  specifications may indicate that every location
  or territory qualifies as an occurrence. These
  are also species for which EOs do not track
  populations.

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Issue

• Since EOs for highly mobile or widely dispersed
  species such as most birds are delimited as
  practical conservation units that include only
  part of a population, how do we delineate them?
• Individual pairs or nests or islands or
  watersheds?
• Any minimal separation distance?

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EO Specs for Bald Eagle

• Current EO Specs (EO class breeding)
• 20 km separation distance
• Proposed EO Specs
• No separation distance
• Each territory/pair is a separate EO, with
  alternate nest locations as source features.
  Typically only the nest locations are known and
  not territory boundaries. Separate Territories
  within a watershed or some arbitrary distance
  (e.g., 20 km) can also be aggregated as a single
  EO in areas where it is impractical to map all
  nest locations.
• Issue Should similar EO Specs be used for other
  raptors? other birds?

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Issue

• We really need review and feedback on the draft
  EO separation distances and procedures as it is
  too costly and impractical to change these except
  when they are shown to be impractical to
  implement or to not reflect populations.
• https//transfer.natureserve.org/download/longterm
  /animal_eo_specs/

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Please please please review the separation
distance spreadsheet!

• Do the separation distances, alternate separation
  procedures, and IE distances seem reasonable???

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Ranking Animal Occurrences
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EO RANKS A MEASURE OF VIABILITY/ ECOLOGICAL
INTEGRITY
EO RANK DESCRIPTION A excellent
B good C fair D
poor E verified extant H
historical F failed to find X
extirpated
To allow determination of conservation priorities
range-wide, ecoregionally, or simply across
jurisdictional boundaries, an occurrence rank
must mean the same thing in all parts of the
range.
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Viability / Ecological Integrity Factors
Size Area of occurrence, amount of species
habitat or sub-population size Condition Reproduc
tive condition (species), composition, structure,
biotic interactions Landscape Context
Landscape-scale ecological processes, adjacency
and connectivity

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Conceptual Framework for Ranking Animal
Occurrences

• A-ranked occurrence excellent estimated
  viability (high probability 95? of persistence
  for 100 years)
• B-ranked occurrence good estimated viability
• C-ranked occurrence fair estimated viability
• D-ranked occurrence poor estimated viability
• Issue Can we recommend a specific probability
  level and appropriate time frame for our
  conceptual framework

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Population Size the primary criterion for
ranking occurrences

• The number of reproductive individuals in an
  occurrence (adult population size) often is the
  most meaningful single indicator of the
  occurrences probability of long-term persistence
  (Reed et al. 2003, OGrady et al. 2004). Current
  population size generally reflects the many
  intrinsic and extrinsic factors impinging on
  occurrences, and thus it should play the major
  role in occurrence viability assessments.

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Down- and up-ranking

• Because adult population size generally reflects
  site quality and reproductive success over
  multiple years, it usually can stand alone as
  indicative of the viability of the occurrence.
• However, additional factors, such as the
  condition or landscape context of the occurrence,
  may influence the occurrence rank.
• Occurrences may be down-ranked or up-ranked,
  depending on whether these additional factors
  decrease or increase the viability of the
  occurrence. Down-ranking is especially
  appropriate if the population is near the lower
  population size threshold level for a particular
  rank.

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Down- and up-ranking factors

• Small habitat patch size
• Known or presumed declining population trend
• Poor recruitment
• Habitat condition
• Landscape context
• NOT potential threats!

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Assessing Viability for Species Occurrences
Viability
High
Low
D
B
C
A
Low
High
Population Size
Population size typically integrates many factors
that affect viability
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Assessing Viability for Species Occurrences
(cont.)
Population Size
High
Low
A
B
C
D
B
C
D
Low reproduction
If a viability-decreasing factor exists, then
down-rank as indicated
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Estimating Population Size

• One simple method involves estimating (1) the
  area or length of occupied habitat of the
  occurrence in question and (2) the probable
  minimum population density for the occurrence.
• Standardized sampling methods that yield
  population indexes (e.g., catch per unit effort
  or CPUE or other indicators of relative
  abundance) may be useful in estimating relative
  occurrence viability, but be cautious in the use
  of CPUE stats.

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Estimating Population Size (cont)

• Relative population size sometimes can be roughly
  estimated through documentation of presence of
  the species in an area and determination of
  habitat patch size.
• Issue Do you agree?
• These methods for estimating occurrence viability
  may have a substantial margin of error, so in
  most cases the resulting occurrence ranks should
  be accordingly imprecise (i.e., a range rank such
  as AC or AB).

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When population size cannot be estimated

• Most occurrences lack information on minimum or
  current population size, and for many of these
  there is no basis for estimation.
• Many occurrences will have to be simply ranked as
  extant (E) until adequate data become available.
  Many occurrence ranks likely will remain E over
  the long term.

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Ranking Occurrences of Long-distance Dispersers

• For reasons of practicality and of keeping
  occurrences of reasonable size, occurrences of
  most birds and other species characterized by
  frequent long-distance dispersal represent
  portions of populations whose viability cannot be
  assessed on the basis of discrete populations or
  metapopulations.

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Issue

• Do we rank occurrences of highly mobile widely
  dispersing species for which EOs do not represent
  populations?
• If so, how do we do it?

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Issue Ranking occurrences that do not represent
populations

• Perhaps rank occurrences according to their
  relative quality rather than by viability per se?
• Distinguish truly exceptional occurrences from
  others?
• This approach may be especially appropriate for
  species whose occurrences may include
  exceptionally large population sizes within
  relatively small areas.

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Conceptual Framework for Ranking Animal
Occurrences

• A-ranked occurrence excellent estimated
  viability (high probability 95? of persistence
  for 100 years) 10,000??? adults
• B-ranked occurrence good estimated viability
  500??? adults
• C-ranked occurrence fair estimated viability
  50??? adults
• D-ranked occurrence poor estimated viability lt
  50???
• Issue Can we recommend a specific probability
  level and appropriate time frame for our
  conceptual framework?
• Issue What are appropriate number of
  reproductive adults to use in this framework for
  different animal species or species groups?

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Reed et al., 2003, Estimates of minimum viable
population sizes for vertebrates andfactors
influencing those estimates, Biological
Conservation 1132334

• The lack of long-term studies for endangered
  species leads to widespread underestimation of
  extinction risk. The results of our simulations
  suggest that conservation programs, for wild
  populations, need to be designed to conserve
  habitat capable of supporting approximately 7000
  adult vertebrates in order to ensure long-term
  persistence.

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Some drafty (daffy?) numbers
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More drafty (daffy?) numbers
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More drafty (daffy?) numbers
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How do we provide better guidance to site
managers and how do we measure conservation
success?

• Changes in A-D occurrence ranks (viability or
  ecological integrity) are a measure of success,
  but occurrence ranks may often be slow to change
• Changes to indicators of subcomponents (key
  ecological attributes) of size, condition, and
  landscape context provide a more sensitive
  measure of conservation success (e.g., positive
  response to management actions)

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Key Ecological Attributes and Indicators

• NatureServe ecologists and The Nature Conservancy
  have decided to assess and separately rate, at
  least for communities, the key ecological
  attributes (which can be aggregated into the 3-4
  rank factors) and indicators for these.
• This information is very useful for managers at a
  site level.
• Issue Should we consider developing global
  attributes and indicators for them?

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Rank Factor Attributes The Heart of EO Rank Specs
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Species example Chinook Salmon ESU
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Site or EO Monitoring

• Site or EO monitoring could involve the
  assessment of key attributes and indicators as
  well as threats
• Occurrence key attributes and indicators (status)
  
• Threats to those attributes and their indicators
  (stressors)

Threat
C
A
Threat
L
S
A
A
EO RANK
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Draft Work Plan for Developing EO Rank
(Viability) Specifications fro Animals

• Complete these for G1-G3 N.A. animals by 2007,
  and other species following as funds permit
• Would a (matching) grants program to
  provinces/states help to get these drafted and
  reviewed?
• Develop lists (global) of key ecological
  attributes of size, condition, and landscape
  context, and provide guidance on excellent, good,
  pair, poor ratings for indicators of these key
  ecological attributes?
• Would this be useful to you or your clients?