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Montana Field Guide

Montana Field Guides

A Rhyacophilan Caddisfly - Rhyacophila rickeri

Species of Concern

Global Rank: G3G4
State Rank: S2
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
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State Rank Reason (see State Rank above)
This Rhyacophilan Caddisfly is currently ranked a "S2" Species of Concern in MT and at risk because of very limited and/or potentially declining population numbers, range and/or habitat, making it vulnerable to extirpation in the state. Limited sites with small populations, and the species is difficult to identify without adult specimens.
  • Details on Status Ranking and Review
    A Rhyacophilan Caddisfly (Rhyacophila rickeri) Conservation Status Review
    Review Date = 09/18/2008
    View State Conservation Rank Criteria
    Population Size

    ScoreU - Unknown

    CommentUnknown.

    Range Extent

    ScoreE - 5,000-20,000 km squared (about 2,000-8,000 square miles)

    Comment5000-20,000km (2,000-8,000square miles)

    Area of Occupancy

    Comment40-200 km (25-125 miles) linear river

    Length of Occupancy

    ScoreLC - 40-200 km (about 25-125 miles)

    Long-term Trend

    ScoreE - Relatively Stable (±25% change)

    CommentSiltation and stream temperature increases with loss of riparian shading and lower snowpack probably contributed to some decline

    Short-term Trend

    ScoreE - Stable. Population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation

    Threats

    ScoreG - Slightly threatened. Threats, while recognizable, are of low severity, or affecting only a small portion of the population or area.

    CommentClimate Change, increasing stream temperatures and lower snowpack could seriously impact the habitat that this speces exists in

    SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.

    ScopeLow - 5-20% of total population or area affected

    ImmediacyLow - Threat is likely to be operational within 5-20 years.

    CommentThreat is not fully operational now, but some areas have been lost.

    Intrinsic Vulnerability

    ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).

    Environmental Specificity

    ScoreB - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.

    CommentCold water stenotherm, cannot survive increases in water temperatures or will have to migrart to cooler temps

 
General Description
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Species Range
Montana Range

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Range Comments
This species occurs in gravelly, high alpine streams in isolated ranges Glacier National Park, Montana, Alberta, British Columbia, Mount Hood and Sisters region of Oregon, and Mount Rainier, Washington (Giersch 2002).

Summary of Observations Submitted for Montana
Number of Observations: 7

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Adults of this species have been collected in July from high gradient first through fourth order streams on Baranof Island, Alaska (Ellis 1978). Nimmo (1971) reported this species emerging in October near very small brooks flowing from moraines at high altitude (2,200 m), occasionally being collected directly from the snow. Giersch (2002) collected this species regularly from very cold, high alpine streams at Logan Pass in Glacier National Park.

Food Habits
Most Rhyacophila species are predators feeding mostly on aquatic insects, especially midges and blackflies.

Ecology
Adults of this species have been collected in July from high gradient first through fourth order streams on Baranof Island, Alaska (Ellis 1978). Nimmo (1971) reported this species emerging in October near very small brooks flowing from moraines at high altitude (2,200 m), occasionally being collected directly from the snow. Giersch (2002) collected this species regularly from very cold, high alpine streams at Logan Pass in Glacier National Park.

Threats or Limiting Factors
In general, cold-stenothermic (cold-water specialists) invertebrate populations are affected by changes to aquatic habitat, such as alteration of flow patterns, streambed substrate, thermal characteristics, and water quality. Alteration and degradation of riparian and aquatic habitat is the primary concern for Montana populations. Specific threats to Montana populations of R. potteri are primarily related to mismanagement of forested riparian areas especially during road-building and timber harvest activities, which can result in sediment and temperature increases.

References
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Citation for data on this website:
A Rhyacophilan Caddisfly — Rhyacophila rickeri.  Montana Field Guide.  .  Retrieved on , from