Ottoe Skipper - Wisconsin Department of Natural Resources

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Ottoe Skipper (Hesperia ottoe) page 1 of 10
Scientific Name (and synonyms): Hesperia Ottoe
Common Name: Ottoe Skipper
Classification: Animalia, Mandibulata, Insecta, Lepidoptera, Hesperiidae
Current Wisconsin Status (and Rank): SC/N (S1)
Other State/Province Status (and Rank): States Colorado (S2), Illinois (S2), Indiana (S1), Iowa
(S2), Kansas (S2S3), Michigan (S1S2), Minnesota (S2), Missouri (S1), Montana (S2S3),
Nebraska (S2), North Dakota (SNR), Oklahoma (S2), South Dakota (S2), Texas (SNR),
Wisconsin (S1), Wyoming (SNR), Manitoba (S1)
National/International Status: G3G4; COSEWIC (Endangered 2005)
Description
1. Physical description of the species:
The Ottoe skipper is a medium sized
butterfly in the family Hesperiidae
(skippers). Its wingspan is between
1¼ and 1 11/16 inches (3.2 to 4.3
cm). The upper sides of the wings
are a warm orange-brown. The male
has an obvious dark stigma (black or dark gray) surrounded with orange and black
borders. The female has more diffuse black borders. The undersides of the wings are
yellow-orange, unmarked in males and sometimes with faint markings on females.
2. Controversial or unsettled taxonomic issues:
None known
3. Summary of (a) biology and natural history and (b) habitat requirements of the species:
(a) The larval hostplants are a range of grasses, including fall witchgrass (Leptoloma
cognatum), little bluestem (Schizachyrium scoparium), and sideoats grama (Bouteloua
curtipendula). Eggs are laid singly, and the resultant caterpillars build shelters from grass
blades tied with silk an inch or two above the soil surface, within which they live. In

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Wisconsin, an Ottoe skipper was observed ovipositing at the base of little bluestem on a
sparsely vegetated, thin soiled prairie bluff top (Armund Bartz-personal observation,
2011) In Minnesota, Ottoe skippers have been recorded ovipositing on various forbs, such
as Blacksamson echinacea (Echinacea angustifolia). In these cases, the forbs are not
larval hosts: the newly hatched larvae dropped off the flowers to feed on the grasses
below.
There is a single brood between June and August with Wisconsin observations ranging
between June 27th and August 14th (WI NHI data). During this period males perch near
host plants often exhibiting "hilltopping behavior" which includes defending territories
from other males and waiting for females. Adults are avid nectar feeders and require
abundant flowers to maintain a population. Nectar sources include milkweeds (Asclepias
sp.), vetch (Vicia sp.), alfalfa (Medicago sativa), bush houstonia (Houstonia sp.), purple
coneflower, leadplant (Amorpha canescens), compassplant (Silphium sp.), sunflower
(Helianthus sp.), and blazing star (Liatris sp.). In Wisconsin, nectaring has been
observed on milkweeds (Asclepias tuberosa and A. viridiflora), prickly pear cactus
(Opuntia sp.), hoary vervain (Verbana stricta), blazingstar (Liatris cylindracea), purple
prairie clover (Dalea purpurea), bergemot (Monarda fistulosa), and mountain mint
(Pycnanthemum virginianum) (Armund Bartz-personal observation, WI NHI data). To
find sufficient nectar, adults may forage in oak savannah and scrub areas
(b) The Ottoe skipper is a prairie-dependent butterfly, although it is found on a range of
regional prairie types, from undisturbed tall- grass and mixed grass prairies on the Great
Plains to sand prairies and old fields with surviving prairie flora near the Great Lakes.
In Wisconsin, it has been reported from dry to dry-mesic hill prairies, sand prairies, and
sand barrens and appears to have some level of area sensitivity as there have been few
reports from small < ~10 acre sites.

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Population Condition
4. Global Distribution/Range:
Ottoe skippers are generally restricted to upland mixed-grass and sand prairie habitats in
the central to north-central plains of the United States, and just across the border in
Manitoba, Canada. Their range is concentrated in a band that extends from southern
Manitoba, eastern Montana, and western North Dakota, south along the high plains and
foothills to central Colorado and northern Texas, and then east across South Dakota,
Nebraska, and Kansas to southwestern Minnesota, western Iowa, and Missouri. Scattered
populations occur further east in southeastern Minnesota, northeastern and east-central
Iowa, southern Wisconsin, northern and west-central Illinois, northwestern Indiana, and
southwestern Michigan (Figure 3). The Ottoe skipper is highly local and uncommon to
rare throughout most of its range (Dana 1991, Brock and Kaufman 2003).
5. State Distribution/Range:
Natural Heritage Inventory records indicate this species has occurred in 9 counties
southwest of a line running between Trempealeau county in the northwest, to Green
county in the southeast. Counties include Trempealeau, Monroe, Vernon, Crawford,
Sauk, Grant, Lafayette, Green, and Dane.Range extent = 21,520 sq km; Area of
occupancy = 14 4km sq grid cells or 64 sq km.
6. Number of Occurrences:
13 WNHI EOs and a 1930 Waukesha county record (Ebner, 1970).
7. Number of Viable/“Good” Occurrences:
Uncertain/questionable; maybe one or two. Activities have been undertaken to
maintain/restore native prairie habitat this species depends on. These activities however
(in particular, intensive extensive frequent prescribed fire) may have had a questionable
affect on viability and in some cases contributed to the sub-detectability of the species at
several sites.

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Source:
WNHI database
(William A. Smith)

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8. Population Size (if known):
As of 2010, there are 4 known occupied sites (3 separate bluffs at Site1, and one at Site2).
9. Extent of field surveys:
The 3 best known sites in the state have been extensively surveyed by multiple observers
since the late 1970's. Site 1 has been annually surveyed between 1998 and 2008 with the
species being sub-detectable. Site 2 has been surveyed 3 years with no detection (last
known attempt, 2008) with the last year of observation yielding 2 individuals in a total of
16 visits. Other known sites surveyed to a much lesser extent with one to few observers.
Results however have been consistent with consistently low numbers for 13 years at a site
until sub-detectability (continues to be surveyed), and relatively consistent numbers at
Site 1. All but one remaining (one not mentioned above, 1978- with "over 12 seen")
known site had 5 or fewer individuals reported with observations taking place between
1983 and 1992. Several of the lesser known sites likely have had few if any additional
surveys since original NHI documented observations.
Trends
10. Short-term Trend:
Declining. Peak numbers appear to have occurred in the late 1980's and early 1990's in
the 3 best known and most monitored sites in the state. Numbers then took a drop in
following years until becoming sub-detectable at many sites. Only one side reported
relatively consistent numbers since 1991.
11. Long-term Trend:
As this is a prairie dependent species and prairie has been nearly eliminated from the state
of Wisconsin, the extent of occurrence, area of occupancy, and number of occurrences has
likely been drastically reduced over the last 200 years.

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Threats
12. Known threats:
Historic loss, degradation, and fragmentation of the prairie landscape have been the
primary factors contributing to the decline and current vulnerability of Ottoe skipper
populations, and continued habitat loss, degradation, and fragmentation are the greatest
potential threats to future populations. Threats to habitat quality and the availability of
critical resources (e.g., nectar plants, larval food plants) include indiscriminant use of
herbicides, invasive exotic species, and encroachment by woody vegetation (native and
exotic). Fire, grazing, and haying can play important roles in maintaining and shaping
prairie ecosystems, so the complete absence of these processes can constitute a threat to
the extent and quality of prairie remnants. However, they can also pose direct and indirect
threats to Ottoe skippers depending on their timing and intensity. Larvae are extremely
vulnerable to direct mortality from fires when they are using aboveground shelters, and
improperly timed fires, grazing, and haying can impact the availability of nectar and
larval food resources at critical times. Other more direct threats to Ottoe skippers can
include extreme weather (e.g., harsh winters, late frosts, unusually cool and wet growing
seasons, and severe storms), indiscriminant use of insecticides, disease, and predation. A
reduction in fitness resulting from genetic isolation may also pose a long-term threat
(Selby, 2005). In addition, some Wisconsin populations have experienced collecting
which may have exacerbated the above threats. For example, one was collected at the a
site in 1996 when three was the highest number reported out of 6 years of reported survey
numbers. Another example comes from a site where it was reported that the species was
"collected multiple times by multiple observers". One of those collections took place in
1996 after 2 previous years of low numbers reported (9 total for 3 surveys in 1995, and 6
total for 3 surveys in 1994). With the precipitous decline in the last 20 years, few
remaining known populations with few individuals per population, collecting could pose
a serious threat in the near future.

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Management/Research Needs
14. Management actions (species, habitat, or people management):
(a.) None to preclude the need for listing as endangered or threatened.
(b.) It is unlikely that any management actions will reduce the extreme rarity of this
species.
Management actions needed to maintain Ottoe skipper populations in Wisconsin:
Utilize fire and grazing to the extent needed to control brush where existing prairie
vegetation occurs while at the same time avoiding use of these tools where brush does not
exist. Combine these tools with herbicide application to brush and trees, and brush
cutting to maintain current extent of prairie vegetation and attempt to expand prairie
vegetation beyond where it currently exists.
Improve connectivity between isolated prairie patches.
15. Research, surveys, and monitoring needed:
General studies examining fire impacts on prairie butterflies and invertebrates (Swengel
1996, Panzer 1998, Swengel 1998, Swengel and Swengel 1999, 2001, Panzer 2002)
provide general principles that can be applied to fire management. Studies of Dakota and
Ottoe skippers by Dana (1991) provide more specific fire management guidelines.
However, there is still a need to conduct additional research examining short- and longterm
effects of prescribed burn programs on Ottoe skippers and the interaction between
prescribed burning and other management options (e.g., grazing and haying) (Selby,
2005). Activities specifically aimed at Ottoe conservation have been limited to the last
few years of management at known sites in Vernon and Crawford counties.
Survey needs come in 4 forms; (1) continued surveys on sites with extant populations to
assess the efficacy of management regimes and to track the few known existing
populations, (2) surveys at NHI element occurrence sites that have previously
documented occurrences but have had little survey effort,(3 ) surveys at other relatively
large prairie sites that may contain extant populations, and (4), continued periodic surveys

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at large sites where populations have been sub-detectable within the last 4-15 years.
Economic Impacts
16. Probable costs from the proposed status change:
Additional Information
Additional survey locations where there is reasonable potential for Ottoe skipper
populations.
Proposed changes in Wisconsin protection Status & rank
17. Proposed Wisconsin Protection Status (End, Thr, SC): Thr or End
18. Basis for proposed WI status change (summary of #s 4 -12):
The Ottoe skipper is a habitat specialist requiring relatively large, high quality prairie
remnents to survive. There have been only 13 reported NHI Element Occurrence records
since 1978. Population declines since the early to mid 1990's has left us with only 4
known occupied sites as of 2010. Although some sites may yield updated records (Fort
McCoy, Brady's Bluff, Ferryville Bluffs) and some sites may produce new records (see
list of potential survey sites), it is highly probable that very few will have the size,
quality, structure, and connectivity to sustain Ottoe skipper populations into the future.
19. Proposed SRANK: S1
20. Proposed WI NHI tracked/watched/not tracked: Tracked

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References
21. List of references used in completing the status assessment, including personal
communications and "gray literature":
Dana, R.P. 1991. Conservation management of the prairie skippers Hesperia dacotae and
Hesperia Ottoe: basic biology and threat of mortality during prescribed burning in spring.
Minnesota Agric. Exp. Sta. Bull. 594-1991. St. Paul, MN. 63 pp.
Ebner, 1970. Butterflies of Wisconsin. Milwaukee Public Museum-Popular Science
Handbook No. 12
Panzer, R. 1998. Insect conservation within the severely fragmented eastern tallgrass
prairie landscape. PhD Dissertation, University of Illinois, Urbana-Champaign, IL.
Panzer, R. 2002. Compatibility of prescribed burning with the conservation of insects in
small, isolated prairie reserves. Conservation Biology 16:1296-1307.
Selby, G. 2005. Ottoe Skipper (Hesperia Ottoe W.H. Edwards): A Technical
Conservation Assessment. Report for the USDA Forest Service, Rocky Mountain
Region, Species Conservation Project.
Shepherd, M. D. 2005. Species Profile: Hesperia Ottoe. In Shepherd, M. D., D. M.
Vaughan, and S. H. Black (Eds). Red List of Pollinator Insects of North America. CD-
ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate
Conservation.
Swengel, A.B. 1996. Effects of fire and hay management on abundance of prairie
butterflies. Biological Conservation 76:73-85.
Swengel, A.B. 1998. Effects of management on butterfly abundance in tallgrass prairie
and pine barrens. Biological Conservation 83:77-89.
Swengel, A.B. and S.R. Swengel. 1999. Observations of prairie skippers (Oarisma
poweshiek, Hesperia dacotae, H. Ottoe, H. leonardus pawnee, and Atrytone arogos iowa)
(Lepidoptera: Hesperiidae) in Iowa, Minnesota, and North Dakota during 1988-1997.
Great Lakes Entomologist 32(4):267-292.
Swengel, A.B. and S.R. Swengel. 2001. Effects of prairie and barrens management on
butterfly faunal composition. Biodiversity and Conservation 10:1757-1785.
Name of preparer(s) and the date prepared: Armund Bartz (9/2/11)
Reviewed and edited by: Terrell J. Hyde and William A. Smith

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Wisconsin NatureServe Element Rank Calculator Results (printed 3/5/2012)
Factor
Categories
and Weights Conservation Rank Factor Comments
1 Range Extent F
F = 20,000-200,000 sq 21,000 sq km (occupied local
km (~8,000-80,000 sq mi) watersheds).
Rarity
weight: 0.5
Trends
0.3
Threats
0.2
Rarity1
Rarity2
X
Trend/Threat
X
Area of
2
Occupancy:
Direct est.
(ecosystems) OR
4 km 2 grid cells
(species) OR
1 km 2 grid cells
(linear species)
Number of
1
Occurrences
2 Population Size
D
D
2 Good Viability: AB
A
B
1
Number of
Occurrences OR
Percent Area
Environmental
Specificity (opt.)
ONLY 1 OF FOLLOWING
3
D = 6-25 4-km2 grid cells
A A = 1 - 5 4 EOs
AB
ONLY 1 OF FOLLOWING
2
AB = None to very few (0-
3) occurrences with good
viability
2 Short-term Trend D D = Decline of 50 - 70%
14 grid cells or 56 sq km.
Viability has not been assessed;
However numbers are declining
at the 4 known sites.
Peak numbers appear to have
occurred in the late 1980's and
early 1990's
1 Long-term Trend C C = Decline of 70 - 80% Tied to prairie loss.
1 Threat Impact A A = Very High
1
Intrinsic
Vulnerability
(opt.)
Calculated Rank
Assigned Rank*
Rank Adjustment
Reasons
Assigned Rank
Reasons
S1
S1
Loss, degradation, and
fragmentation of habitat.
There have been only 13 reported NHI Element Occurrence
records since 1978. Population declines since the early to mid
1990's has left us with only 4 known occupied sites as of 2010
Rank Author William A. Smith and Terrell Hyde (2011)