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Montana Field Guide

Montana Field Guide

Species Status Codes

Provided below are definitions for species conservation status ranks, categories and other codes designated by MTNHP, Federal and State Agencies and non-governmental organizations.

Species of Concern (SOC)

Species of Concern are native taxa that are at-risk due to declining population trends, threats to their habitats, restricted distribution, and/or other factors.  Designation as a Montana Species of Concern or Potential Species of Concern is based on the Montana Status Rank, and is not a statutory or regulatory classification.  Rather, these designations provide information that helps resource managers make proactive decisions regarding species conservation and data collection priorities.  See the latest Species of Concern Reports for more detailed explanations and assessment criteria.

Special Status Species (SSS)

Special Status Species are species that have some legal protections in place, but are otherwise not Montana Species of Concern.  Bald Eagle is a Special Status Species because, although it is no longer protected under the Endangered Species Act and is also no longer a Montana Species of Concern, it is still protected under the Bald and Golden Eagle Protection Act of 1940 (16 U.S.C. 668-668c).  Red Knot is not a Montana Species of Concern, having a state rank of SNA because of a lack of information on its migratory stopover use of Montana's wetlands.  However it is a Special Status Species because it is listed as Threatened in Montana under the Endangered Species Act (16 U.S.C. 1531-1544).

Potential Species of Concern (PSOC)

Potential Species of Concern are native taxa for which current, often limited, information suggests potential vulnerability.  Also included are animal species which additional data are needed before an accurate status assessment can be made.

Status Under Review (Review)

Species designated "Status Under Review" are plant species that require additional information and currently do not have a status rank but may warrant future consideration as Species of Concern.  This category also includes plant species whose status rank is questionable due to the availability of new information or the availability of conflicting or ambiguous information or data.  Species listed in this category will be reviewed periodically or as new information becomes available.

Important Animal Habitat (IAH)

Habitats that are especially important for sustaining populations of individual species or multiple species during particular time periods or throughout the year are designated "Important Animal Habitat".  These areas include: (1) bat roosting areas such as maternity roosts, hibernacula, and bachelor roosts; (2) bird rookeries where species congregate in large numbers to breed, incubate eggs, and raise young due to protections from predators or availability of critical resources; and (3) stopover areas for migratory birds that provide critical food resources that sustain migration.  Important animal habitats that have been mapped are included with other information that is provided for environmental reviews.

Observations (OBS)

A plant or animal observation is a visual, audio, specimen, genetic, or other documentation of a particular species at a location with an assigned spatial precision during a given time period.  Observations must be reported by a credible observer within appropriate time periods and within appropriate habitats or ecological settings in order to be included in MTNHP plant or animal databases.

Species Occurrences (SO)

A Species Occurrence or "SO" (formerly called an 'Element Occurrence') is an area depicting only what is known from direct observation with a defined level of certainty regarding the spatial location of the feature.  If an observation can be associated with a map feature that can be tracked (e.g., a wetland) then this polygon feature is used to represent the SO.  Areas that can be inferred as probable occupied habitat based on direct observation of a species location and what is known about the foraging area or home range size of the species may be incorporated into the Species Occurrence.  A Species Occurrence generally falls into one of the following three categories:

Plants and Lichens A documented location of a specimen collection or observed plant population.  In some instances, adjacent, spatially separated clusters are considered subpopulations and are grouped as one occurrence (e.g., the subpopulations occur in ecologically similar habitats, and are within approximately one air mile of one another). Plant and Lichen SO's are only created for
    - Species of Concern (SOC) or
    - Potential Species of Concern (PSOC)
Animals The location of a specimen collection or of a verified sighting; known or assumed to represent a breeding population.  Additional collections or sightings are often appended to the original record. Animal SO's are only created for
    - Species of Concern (SOC) or
    - Special Status Species (SSS) (ie. Bald Eagle).
Other Significant biological features not included in the above categories, such as bird rookeries, peatlands, or state champion trees.

Structured Surveys

The Montana Natural Heritage Program records information on the locations where more than 80 different types of well-defined repeatable survey protocols capable of detecting an animal species or suite of animal species have been conducted by state, federal, tribal, university, or private consulting biologists.  Examples of structured survey protocols tracked by MTNHP include: visual encounter and dip net surveys for pond breeding amphibians, point counts for birds, call playback surveys for selected bird species, visual surveys of migrating raptors, kick net stream reach surveys for macroinvertebrates, visual encounter cover object surveys for terrestrial mollusks, bat acoustic or mist net surveys, pitfall and/or snap trap surveys for small terrestrial mammals, track or camera trap surveys for large mammals, and trap surveys for turtles.  Whenever possible, photographs of survey locations are stored in MTNHP databases.  MTNHP does not typically manage information on structured surveys for native plants, but structured surveys for invasive species are tracked.

Predicted Suitable Habitat Models

The Montana Natural Heritage Program constructs two types of models for plant and animal species: (1) rule-based, associations with terrestrial habitats for terrestrial species and streams and other water bodies for fish and other aquatic species; and (2) mathematically complex Maximum Entropy models (Phillips et al. 2006, Ecological Modeling 190:231-259) constructed from a variety of statewide biotic and abiotic layers and presence only data for individual species contributed to Montana Natural Heritage Program databases for most terrestrial species.  Full model write ups for individual species that discuss model goals, inputs, outputs, and evaluation in much greater detail are posted on the MTNHP’s Predicted Suitable Habitat Models page.  Evaluations of predictive accuracy and specific limitations are included with the metadata for models of individual species.

Geographic Range Polygons

Year-round geographic range polygons have not yet been defined for most plant species, but are under development.  Native year-round, summer, winter, migratory and historic geographic range polygons as well as polygons for introduced populations have been defined for most animal species for which there are enough observations, surveys, and knowledge of appropriate seasonal habitat use to define them.  These native or introduced range polygons bound the extent of known or likely occupied habitats for non-migratory and relatively sedentary species and the regular extent of known or likely occupied habitats for migratory and long-distance dispersing species; polygons may include unsuitable intervening habitats.  For most species, a single polygon can represent the year-round or seasonal range, but breeding ranges of some colonial nesting water birds and some introduced species are represented more patchily when supported by data.  Some ranges are mapped more broadly than actual distributions in order to be visible on statewide maps (e.g., fish)

Noxious Weeds (Noxious)

Noxious weeds have a destructive impact on Montana's landscape by displacing native plant species, increasing soil erosion, and decreasing wildlife habitat and recreational opportunities.  The Montana Department of Agriculture oversees Montana's Noxious Weed List designating noxious species into one of the following management prioritization categories:  For additional information please visit:

PRIORITY 1A These weeds are not present or have a very limited presence in Montana. Management criteria will require eradication if detected, education, and prevention.

PRIORITY 1B These weeds have limited presence in Montana. Management criteria will require eradication or containment and education.

PRIORITY 2A These weeds are common in isolated areas of Montana. Management criteria will require eradication or containment where less abundant. Management shall be prioritized by local weed districts.

PRIORITY 2B These weeds are abundant in Montana and widespread in many counties. Management criteria will require eradication or containment where less abundant. Management shall be prioritized by local weed districts.

Regulated Weeds: Priority 3 are introduced species that have the potential to cause significant negative impacts in the state.  These plants may not be intentionally spread or sold other than as a contaminant in agricultural products.  The state recommends research, education and prevention to minimize the spread of these plants. 

Aquatic Invasive Species (AIS)

Aquatic Invasive Species have the potential to damage the economy, environment, recreational opportunities and human health of Montana.  The Montana Aquatic Invasive Species Act (AIS Act) was passed by the 2009 Montana Legislature and was revised in the 2011 legislative session for the purpose of undertaking coordinated educational, prevention, detection and management activities to prevent, detect, control and manage aquatic invasive species.  The Montana Aquatic Invasive Species Act recognizes that the departments of Agriculture (MDA); Fish, Wildlife & Parks (FWP); Montana Department of Transportation (MDT); and Department of Natural Resources and Conservation (DNRC) share concerns and responsibilities over aquatic invasive species and seeks to provide collaboration between them whenever possible.  The departments maintain lists of aquatic invasive species and their priority classes (if applicable) within their jurisdiction and identify other departments and other public agencies with overlapping jurisdiction or interests in each species.  Primary agency representatives are the State Noxious Weed Coordinator at MDA, the AIS Coordinator at FWP, the AIS Grant Manager at the DNRC, and the Maintenance Weed Coordinator at MDT.

Currently, there is not an official Aquatic Invasive Species list for the state of Montana.  Species currently shown as Aquatic Invasive Species are from an unofficial list compiled by agency representatives from MDA, DNRC, FWP, and MDT and recognized by the Montana Invasive Species Council.

Forest Pests

Forest Pest Species are those that injure forest tree and shrub species and therefore have the potential to damage the economy, environment, recreational opportunities and human health of Montana.

Currently, there is not an official Forest Pest Species list for the state of Montana.  Species currently shown as Forest Pest Species are from an unofficial list compiled by agency representatives from MDA, DNRC, FWP, and MDT and recognized by the Montana Invasive Species Council.

Agricultural Pests

Agricultural Pest Species are those that cause damage to agricultural production and therefore have the potential to damage the economy and environment of Montana.

Currently, there is not an official Agricultural Pest Species list for the state of Montana.  Species currently shown as Agricultural Pest Species are from an unofficial list compiled by agency representatives from MDA, DNRC, FWP, and MDT and recognized by the Montana Invasive Species Council.

Biocontrol Species (Biocontrol)

Biocontrol species are natural enemies of non-native pest species that have been introduced in order to reduce the vigor or population size of the non-native species.  In Montana biocontrol species have typically been insects introduced to control Noxious Weed species in conjunction with other control efforts such as herbicides, grazing, mowing, and pulling.  Typically, insects are imported from continents where the noxious weeds originated.  Insect predators are carefully tested to be sure they only attack a specific weed and are safe to release in North America.  In Montana, several biological control agents have been successfully used to reduce infestations of noxious weeds such as leafy spurge and spotted knapweed.  County weed coordinators can provide information on implementing biological control methods, and acquiring insects.  See the links and contacts below for more information.

For More Information

Montana Contacts for Biological Weed Control

Non-native Species

Non-native species have been deliberately or accidentally introduced to areas outside of their native geographic range and are able to reproduce and maintain sustainable populations in these areas.  These non-native populations may also be referred to as alien, introduced, invasive, exotic, or non-indigenous.

Accidental Species (Accidental)

Species that arrived in Montana via unknown or uncommon circumstances, which could include weather related events or other migratory disturbances. The term Accidental Species is often assigned to species that have less than 20 verified observations in Montana.

Montana Species Ranking Codes (GRank, SRank)

Montana employs a standardized ranking system to denote global (range-wide) and state status (NatureServe 2006).  Species are assigned numeric ranks ranging from 1 (highest risk, greatest concern) to 5 (demonstrably secure), reflecting the relative degree of risk to the species’ viability, based upon available information.

A number of factors are considered in assigning ranks — the number, size and quality of known occurrences or populations, distribution, trends (if known), intrinsic vulnerability, habitat specificity, and definable threats.  The process of assigning state ranks for each taxon relies heavily on the number of occurrences and Species Occurrence (OE) ranks, which is a ranking system of the quality (usually A through D) of each known occurrence based on factors such as size (# of individuals) and habitat quality.  The remaining factors noted above are also incorporated into the ranking process when they are known.  The “State Rank Reason” field in the Montana Field Guide provides additional information on the reasons for a particular species’ rank.

Rank Definition
G1 S1 At high risk because of extremely limited and/or rapidly declining population numbers, range and/or habitat, making it highly vulnerable to global extinction or extirpation in the state.
G2 S2 At risk because of very limited and/or potentially declining population numbers, range and/or habitat, making it vulnerable to global extinction or extirpation in the state.
G3 S3 Potentially at risk because of limited and/or declining numbers, range and/or habitat, even though it may be abundant in some areas.
G4 S4 Apparently secure, though it may be quite rare in parts of its range, and/or suspected to be declining.
G5 S5 Common, widespread, and abundant (although it may be rare in parts of its range). Not vulnerable in most of its range.
GX SX Presumed Extinct or Extirpated - Species is believed to be extinct throughout its range or extirpated in Montana.  Not located despite intensive searches of historical sites and other appropriate habitat, and small likelihood that it will ever be rediscovered.
GH SH Historical, known only from records usually 40 or more years old; may be rediscovered.
GNR SNR Not Ranked as of yet.
GU SU Unrankable - Species currently unrankable due to lack of information or due to substantially conflicting information about status or trends.
GNA SNA A conservation status rank is not applicable because the species or ecosystem is not a suitable target for conservation activities as a result of being:  1) not confidently present in the state;  2) non-native or introduced;  3) a long distance migrant with accidental or irregular stopovers; or  4) a hybrid without conservation value.

Combination or Range Ranks

Indicates a range of uncertainty about the status of the species (e.g., G1G3 = Global Rank ranges between G1 and G3).
S#, S# Indicates that populations in different geographic portions of the species' range in Montana have a different conservation status (e.g., S1 west of the Continental Divide and S4 east of the Continental Divide).


T# Rank of a subspecies or variety. Appended to the global rank of the full species, e.g. G4T3


Q Questionable taxonomy that may reduce conservation priority-Distinctiveness of this entity as a taxon at the current level is questionable; resolution of this uncertainty may result in change from a species to a subspecies or hybrid, or inclusion of this taxon in another taxon, with the resulting taxon having a lower-priority (numerically higher) conservation status rank.  Appended to the global rank, e.g. G3Q
? Inexact Numeric Rank - Denotes uncertainty; inexactness.
HYB Hybrid - Entity not ranked because it represents an interspecific hybrid and not a species.
C Captive or Cultivated Only - Species at present exists only in captivity or cultivation, or as a reintroduced population not yet established.
A Accidental - Species is accidental or casual in Montana, in other words, infrequent and outside usual range.  Includes species (usually birds or butterflies) recorded once or only a few times at a location.  A few of these species may have bred on the few occasions they were recorded.
SYN Synonym - Species reported as occurring in Montana, but the Montana Natural Heritage Program does not recognize the taxon; therefore the species is not assigned a rank.
B Breeding - Rank refers to the breeding population of the species in Montana.  Appended to the state rank, e.g. S2B,S5N = At risk during breeding season, but common in the winter
N Nonbreeding - Rank refers to the non-breeding population of the species in Montana.  Appended to the state rank, e.g. S5B,S2N = Common during breeding season, but at risk in the winter
M Migratory - Species occurs in Montana only during migration.

U.S. Fish and Wildlife Service (Endangered Species Act) (USFWS)

Status of a taxon under the federal Endangered Species Act of 1973
(16 U.S.C.A. § 1531-1543 (Supp. 1996))

Designation Descriptions

LE Listed endangered: Any species in danger of extinction throughout all or a significant portion of its range (16 U.S.C. 1532(6)).
LT Listed threatened: Any species likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range (16 U.S.C. 1532(20)).
C Candidate: Those taxa for which sufficient information on biological status and threats exists to propose to list them as threatened or endangered.  We encourage their consideration in environmental planning and partnerships; however, none of the substantive or procedural provisions of the Act apply to candidate species.
P Proposed threatened: Any species that is proposed in the Federal Register to be listed under section 4 of the Act.
DM Recovered, delisted, and being monitored - Any previously listed species that is now recovered, has been delisted, and is being monitored.
NL Not listed - No designation.
XE Experimental - Essential population - An experimental population whose loss would be likely to appreciably reduce the likelihood of the survival of the species in the wild.
XN Experimental - Nonessential population - An experimental population of a listed species reintroduced into a specific area that receives more flexible management under the Act.
CH Critical Habitat - The specific areas (i) within the geographic area occupied by a species, at the time it is listed, on which are found those physical or biological features (I) essential to conserve the species and (II) that may require special management considerations or protection; and (ii) specific areas outside the geographic area occupied by the species at the time it is listed upon determination that such areas are essential to conserve the species.
PS Partial status - status in only a portion of the species' range.  Typically indicated in a "full" species record where an infraspecific taxon or population, that has a record in the database has USESA status, but the entire species does not.
PS:value Partial status - status in only a portion of the species' range. The value of that status appears in parentheses because the entity with status is not recognized as a valid taxon by Central Sciences (usually a population defined by geopolitical boundaries or defined administratively, such as experimental populations.)

For example, Yellow-billed Cuckoo (Coccyzus americanus) is ranked PS:C.  Partial Status - Candidate.  Designated as a Candidate in the Western U.S. Distinct Population Segment (DPS) (subspecies occidentalis)
BGEPA The Bald and Golden Eagle Protection Act of 1940 (BGEPA) - (16 U.S.C. 668-668c) prohibits anyone, without a permit issued by the Secretary of the Interior, from taking bald or golden eagles, including their parts, nests, or eggs.  The BGEPA provides criminal and civil penalties for persons who take, possess, sell, purchase, barter, offer to sell, purchase or barter, transport, export or import, at any time or any manner, any bald eagle ... [or any golden eagle], alive or dead, or any part, nest, or egg thereof.  The BGEPA defines take as pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, molest or disturb.  "Disturb" means to agitate or bother a bald or golden eagle to a degree that causes, or is likely to cause, based on the best scientific information available, 1) injury to an eagle, 2) a decrease in its productivity, by substantially interfering with normal breeding, feeding, or sheltering behavior, or 3) nest abandonment, by substantially interfering with normal breeding, feeding, or sheltering behavior.  In addition to immediate impacts, this definition also covers impacts that result from human-induced alterations initiated around a previously used nest site during a time when eagles are not present, if, upon the eagles return, such alterations agitate or bother an eagle to a degree that injures an eagle or substantially interferes with normal breeding, feeding, or sheltering habits and causes, or is likely to cause, a loss of productivity or nest abandonment.
MBTA The Migratory Bird Treaty Act (MBTA) - (16 U.S.C. §§ 703-712, July 3, 1918, as amended 1936, 1960, 1968, 1969, 1974, 1978, 1986 and 1989) implements four treaties that provide for international protection of migratory birds.  The statute’s language is clear that actions resulting in a "taking" or possession (permanent or temporary) of a protected species, in the absence of a U.S. Fish and Wildlife Service (USFWS) permit or regulatory authorization, are a violation of the MBTA.  The MBTA states, "Unless and except as permitted by regulations ... it shall be unlawful at any time, by any means, or in any manner to pursue, hunt, take, capture, kill ... possess, offer for sale, sell ... purchase ... ship, export, import ... transport or cause to be transported ... any migratory bird, any part, nest, or eggs of any such bird .... [The Act] prohibits the taking, killing, possession, transportation, import and export of migratory birds, their eggs, parts, and nests, except when specifically authorized by the Department of the Interior."  The word "take" is defined by regulation as "to pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to pursue, hunt, shoot, wound, kill, trap, capture, or collect."  The USFWS maintains a list of species protected by the MBTA at 50 CFR 10.13.  This list includes over one thousand species of migratory birds, including eagles and other raptors, waterfowl, shorebirds, seabirds, wading birds, and passerines.  The USFWS also maintains a list of species not protected by the MBTA.  MBTA does not protect species that are not native to the United States or species groups not explicitly covered under the MBTA; these include species such as the house (English) sparrow, European starling, rock dove (pigeon), Eurasian collared-dove, and non-migratory upland game birds.
BCC The 1988 amendment to the Fish and Wildlife Conservation Act mandates the U.S. Fish and Wildlife Service to identify species, subspecies, and populations of all migratory nongame birds that, without additional conservation actions, are likely to become candidates for listing under the Endangered Species Act.  Birds of Conservation Concern 2008 (BCC 2008) is the most recent effort to carry out this mandate.  The overall goal of this report is to accurately identify the migratory and non-migratory bird species (beyond those already designated as federally threatened or endangered) that represent the Service's highest conservation priorities.  BCC10, BCC11, and BCC17 designations represent inclusion on the Birds of Conservation Concern list for Bird Conservation Region 10, 11, and 17 in Montana, respectively.

Bureau of Land Management (BLM)

BLM Sensitive Species are defined by the BLM 6840 Manual as those that normally occur on Bureau administered lands for which BLM has the capability to significantly affect the conservation status of the species through management.  The State Director may designate additional categories of special status species as appropriate and applicable to his or her state's needs.  The sensitive species designation, for species other than federally listed, proposed, or candidate species, may include such native species as those that:

  1. could become endangered in or extirpated from a state, or within a significant portion of its distribution in the foreseeable future,
  2. are under status review by FWS and/or NMFS,
  3. are undergoing significant current or predicted downward trends in habitat capability that would reduce a species’ existing distribution,
  4. are undergoing significant current or predicted downward trends in population or density such that federally listed, proposed, candidate, or State listed status may become necessary,
  5. have typically small and widely dispersed populations,
  6. are inhabiting ecological refugia, specialized or unique habitats, or
  7. are State listed but which may be better conserved through application of BLM sensitive species status. Such species should be managed to the level of protection required by State laws or under the BLM policy for candidate species, whichever would provide better opportunity for its conservation.

Designation Descriptions

Sensitive Denotes species listed as sensitive on BLM lands
Special Status Denotes species that are listed as Endangered or Threatened under the Endangered Species Act

U.S. Forest Service (USFS)

U.S. Forest Service Manual (2670.22) defines Sensitive Species on Forest Service lands as those for which population viability is a concern as evidenced by a significant downward trend in population or a significant downward trend in habitat capacity.  The Regional Forester (Northern Region) designates Sensitive species on National Forests in Montana.  These designations were last updated in 2007 and they apply only on USFS-administered lands.

Designation Descriptions

Endangered Listed as Endangered (LE) under the U.S. Endangered Species Act.
Threatened Listed as Threatened (LT) under the U.S. Endangered Species Act.
Sensitive Listed as a Sensitive Species by USFS Northern Region (R1).

FWP State Wildlife Action Plan (FWP SWAP)

In recent years states have received federal funding to develop State Wildlife Action Plans.  Montana's first SWAP, the Comprehensive Fish and Wildlife Conservation Strategy, was approved by the U.S. Fish and Wildlife Service in 2006.  An updated SWAP was subsequently approved by the U.S. Fish and Wildlife Service in 2015 to assist with guiding conservation efforts throughout Montana by identifying species and habitats that are in greatest need of conservation.  Montana vertebrates with a state conservation status rank of S1, S2, or S3 and the Western Pearlshell Mussell were included as Species of Greatest Conservation Need (SGCN).  SGCN with state conservation status ranks of S1, S2, and S3 are listed on Montana Natural Heritage Program websites as SGCN1, SGCN2, and SGCN3, respectively.  The SWAP also identifies Species of Greatest Inventory Need (SGIN) if they are a Species of Concern or Potential Species of Concern and they lack, or have outdated, statewide baseline surveys that can be used to assess their state conservation status.

Percent of Global Breeding Range in MT

The percentage of the species’ Global Breeding Range represented by its Breeding Range in Montana.

Percent of MT that is Breeding Range

The percentage of Montana’s Total Area identified as the Breeding Range of this species.


A short description of the general habitat in which you are most likely to find this species.

Partners In Flight (PIF)

Partners In Flight (PIF) is a partnership of federal and state agencies, industry, non-governmental organizations, and many others, with the goal of conserving North American birds.  In 1991, PIF began developing a formal species assessment process that could provide consistent, scientific evaluations of conservation status across all bird species in North America, and identify areas most important to the conservation of each species.  This process applies quantitative rule sets to complex biological data on the population size, distribution, population trend, threats, and regional abundance of individual bird species to generate simple numerical scores that rank each species in terms of its biological vulnerability and regional status.  The process results in global and regional conservation assessments of each bird species that, among other uses, can be used to objectively assign regional and continental conservation priorities among birds.

The species assessment scores and process has recently been updated!  Check out the new scores and make sure to download and read the updated Handbook on Species Assessment, which contains important information on the how scores are derived and used in the assessment process.  Note that currently only breeding-season regional scores are available for BCRs.  We hope to have non-breeding scores available soon.  For those needing access to the previous versions of the PIF Species Assessment Database, including past regional scores for physiographic areas, click here.

Montana Native Plant Society Threat Category (MNPS)

The MNPS Threat Category process was initiated in 2006 at the Montana Plant Conservation Conference with the formation of a committee represented by federal, state and private botanists, ecologists and biologists.  The objectives were to:  1) Evaluate threats impacting Montana's Plant Species of Concern and to classify species according to their level of imperilment/risk as a result of these threats.  2) Develop a ranking system based on the impacts of the identified threats to the species' viability in the state.  The result of this process is a 4-tier threat ranking system for Plant Species of Concern in Montana.  The threat categories are:

Category 1 The viability of the species in the state is Highly Threatened by one or more activities.  Associated threats have caused or are likely to cause a major reduction of the state population or its habitat that will require 50 years or more for recovery, 20% or more of the state population has been or will be affected, and the negative impact is occurring or is likely to occur within the next 5 years.
Category 2 The viability of the species or a portion of the species habitat in the state is Threatened by one or more activities, though impacts to the species are expected to be less severe than those in Category 1.  Associated threats exist but are not as severe, wide-ranging or immediate as for Category 1, though negative impacts are occurring or are likely to occur.
Category 3 The viability of the species in the state is Not Threatened or the Threats are Insignificant.  Associated threats are either not known to exist, are not likely to occur in the near future or are not known to be having adverse impacts that will severely affect the species' viability in the state.
Category 4 Assessment not possible due to insufficient and/or conflicting information on potential threats to the species.

Please visit the MNPS website at for additional information on MNPS Threat Categories or for MNPS contact information.

Montana Coefficient of Conservatism Values (C-value)

The Montana Coefficient of Conservatism (C-) value measures a plant species' tolerance to disturbance (natural and/or human derived) and its fidelity to a specific habitat in Montana.  A process for assigning C-values to Montana plants was developed in 2005 and revised in 2015 and 2016.  A panel of Montana's botany experts determined the plant's C-value using a dichotomous key and definitions published by Zomlefer, et al. (2013), in addition to, expertise, literature, and herbarium records.

As of 2015, approximately 1,623 native and non-native plants have been assigned a C-value.  The C-value scale ranges from 0 to 10 based on the following definitions:

Non-Native Montana Species
 1relatively benign
Native Montana Species
 Opportunistic, Broad Ecological Tolerance
 2exhibits a broad range of ecological tolerance and is more or less restricted to areas of human disturbance
 Non-Opportunistic, Intermediate Ecological Tolerance
 3exhibits an intermediate range of ecological tolerance, typifies a stable phase of a native community, and thrives and/or persists under natural or human disturbance
 4exhibits an intermediate range of ecological tolerance, typifies a stable phase of a native community, and persists but does not thrive with some natural or human disturbance
 5exhibits an intermediate range of ecological tolerance, typifies a stable phase of a native community, and persists but does not thrive with a little natural or human disturbance
 Non-Opportunistic, Narrow Ecological Tolerance
 6exhibits a moderate fidelity to a more or less narrow range of ecological tolerance, typifies a stable or near climax community, and tolerates limited natural or human disturbance (unless surrogate for fire or other natural disturbance)
 7exhibits a moderate fidelity to a somewhat narrow range of ecological tolerance, typifies a stable or near climax community, and does not tolerate disturbance
 8exhibits a moderate fidelity to a narrow range of ecological tolerance, typifies a stable or near climax community, and does not tolerate disturbance
 9exhibits a high fidelity to a narrow range of ecological tolerance, typifies a stable or near climax community, and does not tolerate disturbance
 10exhibits a very high fidelity to a very narrow range of ecological tolerance that typifies a stable or near climax community and does not tolerate disturbance

Zomlefer, W., L. Chafin, R. Carter, and D. Giannasi.  2013.  Coefficient of Conservatism Rankings for Flora of Georgia: Wetland Indicator Species.  Southeastern Naturalist, 12(4): 790-808.  Eagle Hill Institute.

Relative Density Map

Relative density maps display the relative density of observations submitted in each latilong, quarter latilong, or quarter-quarter latilong.  The maps are constructed by: (1) calculating the total number of observations in each latilong block; (2) counting the number of distinct total values; (3) dividing the total number of distinct values by 5 to create 5 map classes (any remainders are sequentially added to lower map classes); and (4) color coding each latilong block with the corresponding map class.

Recency Map

Recency maps display the most recent observation reported in each latilong, quarter latilong, or quarter-quarter latilong and color codes each as 0-5, 5-10, 10-15, 15-20, and 20+ years ago.

Bird "Observation Type" Maps - Definition of STATUS

Each bird sighting is entered in our database with a "status" code (B, b, t, W, or w; see criteria below) to indicate information about the bird when it was observed.  The status of a bird describes whether it was breeding, presumed to be breeding, transient ("passing through"), or wintering in the area in which it was seen.

There are two seasons which are important. The breeding season is defined by sightings made between February 16 and December 14; while the winter season is defined by observations made between December 15 and February 15 (see below).

The symbols used are defined as follows:

Breeding Season (February 16 - December 14)
Direct evidence of breeding:  evidence that eggs or young have been produced.  Breeding is not assumed simply by presence or behavior.  "B" is used only if one of the following criteria are met:
  • Occupied nest – adult attending a nest with eggs or nestlings (incubation or brooding), or adults entering or leaving nest site in circumstances indicating an occupied nest (includes high nests or cavities, the contents of which cannot be seen).
  • Recently fledged young (of altricial species) incapable of sustained flight, or downy young (of precocial species) restricted to the area by dependence on adults or limited mobility.
  • Adults attending young - adult carrying food or fecal sac for young, or feeding recently fledged young.
  • Nest with egg(s) that can be clearly identified.  The presence of cowbird eggs or young is confirmation of breeding for both cowbird and host species.
  • Used nest with eggshell, or just eggshell, found (identification must be convincing for such records to be accepted, and cannot be based on the nest alone).
Indirect or circumstantial evidence of breeding.  "b" is used if only if one or more of the following criteria are met:
  • Singing males or territorial birds observed in suitable nesting habitat during the breeding season.
  • Courtship behavior or copulation.
  • Adults visiting a probable nest site.
  • Agitation behavior, distraction display, feigning injury, or anxiety call from an adult.
  • Nest building.
  • Physiological evidence of breeding (incubation patch or egg in oviduct) based on bird in hand.
  • Independent young of the year unaccompanied by adult (for non-migratory species or prior to normal migration).
No evidence of breeding, no breeding behavior.  "t" is used to indicate presence of any species (resident, migrant, or transient) that exhibits no breeding behavior at the time observed.  Behavior activities outside the winter season that do not fit "B" or "b" should be considered "t".  See "B" and "b" above to determine if a behavior constitutes direct or indirect evidence of breeding.
Winter Season (December 15 - February 15)
Overwintering.  "W" is used to indicate regular observations of the species during the winter period.  Regular is defined as at least 3 days between 15 December and 14 January and 3 days between 15 January and 15 February.  "W" can be documented two ways: (1) an individual observer submits data with dates for when the bird was observed during the winter months, following the above criteria, or (2) multiple "w" records in the Montana Bird Distribution database for the same latitude/longitude block during the same winter season are used to generate a "W" following the above date criteria.  Individuals submitting data need to include the dates for which the bird was observed during the winter period in the comments section of the report form.
Observed during the winter season, but not confirmed overwintering.  "w" is used to indicate that the species was observed at least once between 15 December and 15 February, but not regularly during the winter season.

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