Icaricia icarioides fenderi - (Macy, 1931)
Fender's Blue
Other English Common Names: Fender's blue
Synonym(s): Plebejus icarioides fenderi Macy, 1931
Taxonomic Status: Accepted
Related ITIS Name(s): Plebejus icarioides fenderi Macy, 1931 (TSN 778947)
Unique Identifier: ELEMENT_GLOBAL.2.119043
Element Code: IILEPG801C
Informal Taxonomy: Animals, Invertebrates - Insects - Butterflies and Moths - Butterflies and Skippers
 
Kingdom Phylum Class Order Family Genus
Animalia Mandibulata Insecta Lepidoptera Lycaenidae Icaricia
Genus Size: B - Very small genus (2-5 species)
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Concept Reference
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Concept Reference: Pelham, J. P. 2008. A catalogue of the butterflies of the United States and Canada with a complete bibliography of the descriptive and systematic literature. The Journal of Research on the Lepidoptera. Volume 40. 658 pp. Revised 14 February, 2012.
Concept Reference Code: B08PEL01EHUS
Name Used in Concept Reference: Plebejus icarioides fenderi
Conservation Status
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NatureServe Status

Global Status: G5T1
Global Status Last Reviewed: 24Feb2009
Global Status Last Changed: 01Sep1998
Rounded Global Status: T1 - Critically Imperiled
Reasons: The total number of adults is probably under 3000 some years. Area of occupance apparently about 165 hectares. There are only two apparently two occurrences with at least moderately good viability, and possibly only one other that is minimally viable (EO rank C). Eight other occurrences are marginal (suggested EO rank CD)
Nation: United States
National Status: N1 (01Sep1998)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Oregon (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (25Jan2000)
Comments on USESA: Listed Endangered as Icaricia icarioides fenderi.
U.S. Fish & Wildlife Service Lead Region: R1 - Pacific

NatureServe Global Conservation Status Factors

Range Extent: 250-1000 square km (about 100-400 square miles)
Range Extent Comments: Small area in Oregon, mostly on west side of, and no more than 33 miles frow, the Willamette River. Occupied habitat fragments in Lane, Polk, Benton and Yamhill Counties (USFWS, 2008). The recent range is almost linear from north to south and extends a bit under 100 miles, widening at the southern end to around 20 miles, but mostly much less. The range would fit into a polygon of less than 1000 square miles.

Area of Occupancy: 1-25 4-km2 grid cells
Area of Occupancy Comments: No more than 400 hectares of potential habitat remains as of the 1990s, of which about 165 hectares are occupied. More recent estimates of occupied habitat are virtually identical.

Number of Occurrences: 1 - 20
Number of Occurrences Comments: Xerces Society reports 32 colonies in 165 hectares, with 24 on 3.5 hectares or less Most are thought to be declining and/or probably are no longer viable. These probably resolve into about 26 occurrences, including two robust metapopulations (likely NatureServe EO rank BC), one other viable population (C), and eight occurrences that may or may not be marginally viable (CD); so 3-11 viable occurrences. The draft recovery plan (USFWS, 2008) tabulates 32 sites with census data between 2000 and 2006, but one site had no observations. Of the 30 that apparently are still occupied as of 2006, four apparently should be combined with three others as metapopulations leaving 26 putative occurrences. These can be roughly ranked using NatureServe standards, with C being occurrences with a fair potential for persisting for the next 20 years, and B rank used for occurrences with a good chance of not only persisting but also maintaining current genetic diversity. Nearly all population biologists would accept that populations that cannot consistently maintain at least 200 adults each generation probably will not maintain genetic quality over time--most would argue for a higher minimum. Since the maximum number of population estimates is seven, it is virtually certain all populations fall lower than the minimum reported, and it is very likely any that any commonly under 50 adults will crash beyond recovery as did Fern Corner during these observations. Numbers are not based on mark-release-recapture, although at least some estimates do try to account for residency and turnover (Schultz, 1995), so it is possible most or all are underestimates. It is assumed all larvae complete development within one year (see other factors).

The Nature Conservancy's Willow Creek Preserve has three major demes on managed habitat which together apparently reliably produced over 150 adults over seven years, and over 1000 in three of these years. However given low numbers in 2005, probably only one deme would rank C on its own. The largest (the main site) is possibly in decline overall since by far the highest number estimated was 1147 in 2000, and the two lowest were 337 in 2006 and 129 in 2005. This metapopulation could reasonably be ranked BC reflecting fluctuations and uncertainties. TNC's Coburg Ridge is over 200 adults in two of four years, but fell to an estimated 23 adults in 2005, but could rank as C in part due to on-going management. Basket Butte (USFWS) is probably the largest occurrence and probably functions as two demes, although only one of two units appears to harbor significant numbers. Still with over 1000 adults in at least three of seven years and over 200 in all years, this one seems likely to merit BC. USFWS states that PVA indicates low potential for this taxon to survive for 100 years, but this is not factored into ranks here. One would guess that the two Green Oaks sites would be a metapopulation but with pooled totals of 5 in 2000 and 14 in 2001, a rank of C seems unjustified based on the information given even with over 130 adults in 2004-2006, so CD. Deer Creek Park is not counted as an occurrences because no adults are seen there most years. If the remaining 21 are ranked as separate occurrences there appears to be enough uncertainty about only seven to justify a rank of CD. The other 14 appear to rate a straight D, for example eight of these 10 or fewer adults estimated least once in only four to seven years, including Oak Creek Rd. which is doubtfully an actual population since the maximum estimate is three.

Population Size: 2500 - 10,000 individuals
Population Size Comments: Total population probably less than 3000 in some years. See Schultz (1995) who suggests about 1400 individuals for Lane County in 1993 and 850 in 1994 for well-studied populations. Her estimates may be a bit low, since they are not based on mark-release-recapture. USFWS (2008) suggests about 3000-5000 citing her work.

Number of Occurrences with Good Viability/Integrity: Very few (1-3)
Viability/Integrity Comments: Two occurrences seem to approach B rank (good viability) standards, another seems viable, and seven more are suggested as CD rank. See number of EOs comments field.

Overall Threat Impact: High
Overall Threat Impact Comments: Most populations are small, with under 50 adults in at least some years since 2000, and so very vulnerable to "winking out", and only about three large ones are clearly viable. The primary foodplant is also listed as Federally Threatened. Some colonies on private land are still subject to possible elimination by development, agriculture, livestock use, and tree planting or even just lack of management. Invasive weeds such as Himalayan blackberry and Scotch broom and wildfire are potential threats on protected sites on public land. The three largest populations are for now fairly secure being owned and managed by the Nature Conservancy and US Fish and Wildlife Service.

Short-term Trend: Relatively Stable (<=10% change)

Long-term Trend: Decline of >90%
Long-term Trend Comments: USFWS (2008) states that 99.9% of presettlement habitat has been lost.

Intrinsic Vulnerability Comments: Most populations are small enough that they could be lost due to natural fluctuations.

Other NatureServe Conservation Status Information

Protection Needs: Some populations on private lands may be significant enough to warrant protection probably by purchase.

Distribution
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Global Range: (250-1000 square km (about 100-400 square miles)) Small area in Oregon, mostly on west side of, and no more than 33 miles frow, the Willamette River. Occupied habitat fragments in Lane, Polk, Benton and Yamhill Counties (USFWS, 2008). The recent range is almost linear from north to south and extends a bit under 100 miles, widening at the southern end to around 20 miles, but mostly much less. The range would fit into a polygon of less than 1000 square miles.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States OR

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
OR Benton (41003), Lane (41039), Linn (41043), Polk (41053), Washington (41067), Yamhill (41071)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
17 Upper Willamette (17090003)+, Mckenzie (17090004)+, Middle Willamette (17090007)+, Yamhill (17090008)+, Tualatin (17090010)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: Fender's blue (butterfly)
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Terrestrial Habitat(s): Grassland/herbaceous
Habitat Comments: Primary habitat factor is presence of abundant larval foodplants.
Adult Food Habits: Nectarivore
Immature Food Habits: Herbivore
Food Comments: Lare feed exclusivley on certain lupine, mainly LUPINUS SULPHUREUS var. KINCAIDI occasionally L. LAXIFLORUS and ALBICAULIS.
Adult Phenology: Diurnal
Phenology Comments: One brood adults from the end of April into June. Larvae feed in early summer and again in early spring. It is possible that larvae may sometimes extend diapause over more than one winter.
Economic Attributes Not yet assessed
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Management Summary
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Biological Research Needs: See USFWS (2008) and references. More information relative to metapopulation dynamics seems like the most important issue. Documentation of holdover of diapausing larvae would have significant implications regarding population viability, but this probably does not occur. Continued monitoring needed
Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 24Feb2009
NatureServe Conservation Status Factors Author: Schweitzer, D.F.
Element Ecology & Life History Edition Date: 26May2000
Element Ecology & Life History Author(s): SCHWEITZER, D.F.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Andow, D.A., R.J.Baker, C.P. Lane (eds.) 1994. Karner Blue Butterfly: a symbol of a vanishing landscape. Misc. publ. 84-1994 Minnesota Agric. Expt. Station, Univ. of Minnesota, St. Paul, MN, 222pp.

  • Gall, L. F. 1985. Measuring the Size of Lepidopteran Populations. Journal of Research on the Lepidoptera. 24(2):97-116.

  • Givnish, T., Menges, E., and Schweitzer, D.F. 1988. Minimum area requirements for long-term conservation of the Albany Pine bush and Karner blue butterfly. Consultants report prepared for the City of Alabny, NY, Malcom Pirnie, Inc.

  • Opler, P. A., and A. D. Warren. 2002. Butterflies of North America. 2. Scientific Names List for Butterfly Species of North America, north of Mexico. C.P. Gillette Museum of Arthropod Diversity, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado. 79 pp.

  • Pelham, J. P. 2008. A catalogue of the butterflies of the United States and Canada with a complete bibliography of the descriptive and systematic literature. The Journal of Research on the Lepidoptera. Volume 40. 658 pp. Revised 14 February, 2012.

  • Pohl, G.R., B. Patterson and J.P.  Pelham. 2016. Annotated taxonomic checklist of the Lepidoptera of North America, North of Mexico. Working paper published online by the authors at ResearchGate.net (May 2016). 766 pp. Online:https://www.researchgate.net/publication/302570819_Annotated_taxonomic_checklist_of_the_Lepidoptera_of_North_America_North_of_Mexico

  • Powell, J. 1987. Records of prolonged diapause in Lepidoptera. Journal of Research on the Lepidoptera 25(2):83-109.

  • Schultz, Cheryl B. 1995. Status of the Fenders Blue Butterfly (Icaricia icarioides fenderi) in Lane County, Oregon: a year of declines. Unpublished report to Oregon Natural Heritage Program and USFWS. 58pp.

  • Schweitzer, D.F. 1994a. Prioritizing Karner Blue Butterfly Habitats for Protection Activities. Chapter 19, pp. 173-183 in: Andow, D.A., R.J.Baker, and C.P. Lane (eds.) Karner Blue Butterfly: a symbol of a vanishing landscape. Misc. Publ. 84-1994 Minnesota Agric. Expt. Station, Univ. of Minnesota, St. Paul, MN. 222 pp.

  • U.S. Fish and Wildlife Service (USFWS). 1994. Category and Listing Priority Form.

  • U.S. Fish and Wildlife Service (USFWS). 1996. Endangered and Threatened Wildlife and Plants; Review of Plant and Animal Taxa That Are Candidates for Listing as Endangered or Threatened Species. Federal Register 61(40):7596-7613.

  • U.S. Fish and Wildlife Service (USFWS). 1997. Category and Listing Priority Forms.

  • U.S. Fish and Wildlife Service (USFWS). 2008. Draft recovery plan for the prairie species of Western Oregon and Southwestern Washington. U.S. Fish and Wildlife Service, Portland, Oregon. x + 212 pp. Available: http://ecos.fws.gov/docs/recovery_plan/080922_1.pdf.

  • U.S.Fish and Wildlife Service (USFWS). 1998. Endangered Status for Erigeron decumbens var. decumbens (Willamette Daisy) and Fender's Blue Butterfly (Icaricia icarioides fenderi) and Proposed Threatened Status for Lupinus sulphureus ssp. kincaidi (KIncaid's lupine). Proposed Rule. Federal Register 63(17): 3863-77

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