Biogeography of Behr’s Hairstreak, behrii columbia (McDunnough 1944) in the South Okanagan (Analysis of data collected in 2003 and earlier)

PART 1. Inventory Survey and Mapping

Introduction

Behr’s Hairstreak ( Satyrium behrii W. H. Edwards, 1870) is confined to the south Okanagan Valley of British Columbia in Canada(Guppy & Shepard, 2001). Kondla (2003) estimates the Canadian distribution at less than 1% of the global distribution of this species. The species ranges south to southern California, northern Arizona and New Mexico, and an outlier population is found in northwest Texas. From about the middle of Oregon, north to British Columbia, the species’ range narrows to a thin band terminating in British Columbia south of Penticton. This range follows the eastern boundaries of the Oregon and South Cascades Ecogeographic Provinces into Washington, and parallels the course of the Columbia eastward to Spokane County, and northward along the Okanagan river system into BC (Opler, 1999, Pyle 2002). The subspecies Satyrium behrii columbia (McDunnough,1944) is the taxon found in BC and throughout Cascadia (Pyle, 2002). The type locality is at Fairview near Oliver (Guppy & Shepard, 2001). In Cascadia, including BC, antelope brush ( (Pursh)) is the only known larval foodplant of Behr’s Hairstreak (Guppy & Shepard 2001, Shepard 2000, Pyle 2002). Previous field work indicates that yarrow ( Achillea millefolium L.) is the most widely utilized nectar source. Smooth sumac ( Rhus glabra L.), gray horse-brush ( Tetradymia canescens DC), baby’s breath ( Gypsophila paniculata L.) sweet clover ( Melilotus sp Mill.) and ocean spray( Holodiscus discolor (Pursh)) have also been reported as nectar sources in the Okanagan (pers comm. S. Bunge, Or. Dyer, C.S. Guppy and per obs). Pyle (2002) reports it using buckwheats ( Eriogonum sp Michx.) as a nectar source but this has not been observed in the Okanagan to my knowledge. Kondla (2003) comments that research is needed to determine whether Behr’s hairstreak is involved in a mutualist relationship with ants. This is a very cogent suggestion since the larvae of this species possesses a honey gland and dendritic setae, which are indicative of ant association (Ballmer & Pratt 1989). Behr’s Hairstreak larvae also have been found to be highly effective at inducing ant attendance in an experimental study using and ant species found in California (Ballmer & Pratt 1991). There is apparently no direct field evidence concerning possible ant association in nature. It is important to attempt to assess the relationship with ants in Okanagan populations. Lycaenid butterflies may be found in association with several species of ant. Some of these associations may be beneficial to the fitness of the involved, while others may have a negative effect on survival, depending on the species of ant attending the larvae ( Fraser et al 2001). The type of relationship, and the ant species involved, may well be an important factor in determining the habitat quality of sites, in addition to the presence of antelope brush and adequate nectar sources. In the Silver Studded Blue (Plebejus argus L. 1758) presence of its ant mutualist has been found to be more effective than nectar source density in determining dispersal (Seymour et al 2003).

1 Therefore it may be important to assess the ant diversity and abundance, at known and potential habitat sites.

Methods Surveys for Behr’s Hairstreak were carried out between June 16 th and June 27 th of 2003 . Surveys ranged from approximately the northern boundary of Osoyoos in the south, to the north end of Vaseux Lake on the east side of the valley, and to about ¼ of the way up Vaseux Lake on the west side. Samples were conducted by teams of observers traversing the terrain at a slow walking pace, maintaining a distance between observers of about 20 m. Particular attention was focused on yarrow as it is frequently used by nectaring hairstreaks. Antelope brush plants encountered were scanned for the presence of butterflies and tapped with net poles to encourage any unseen to take flight. Any Behr’s Hairstreak detected was recorded along with the time, UTM coordinates, a brief description of its activity (eg nectaring on yarrow), and a crude characterization of the habitat within a 10m radius of the sighting. Start and stop times were also recorded so that Behr’s Hairstreak encounter rates could be expressed as sightings/observer/hour. Sampling time was expressed as observer-minutes from a calculation based on duration of the transect, and the number of observers. An effort was made to obtain complete coverage of the polygon area being surveyed. Survey personnel included both those with previous field experience and first-time volunteers. In practice, sampling distance between observers varied considerably, transect start and stop times were often omitted, and polygon coverage varied among sessions. Where session durations were not directly available, times of first and last sightings were used to obtain crude biased estimates. Data treated in this way underestimates the sampling times, and correspondingly overestimates the encounter rate

Surveys for Behr’s and California Hairstreaks were conducted mainly in polygons where antelope brush was a recognized component (Harper et al., 1996, Lea et al ., 1991. A small number of sightings (4) were made in other polygon types in this year’s surveys and a number are included from previous years (8), but most of the surveying was confined to map units AN, AE , and PA(see appendix I for definitions). These map units were used as the basis for drawing habitat islands, composed of networks of contiguous or nearly contiguous (less than 1km separation) antelope brush containing units. The habitat islands resulting from this analysis are meant as heuristic fictions, enabling discussion of the present results and yielding suggestive rationales for future surveys. Present boundaries are intended to highlight the degree of apparent connectivity of existing habitat units in the region and outline the suitable polygons with about a five hundred metre boundary in most of the map. Computer generated mapping was not employed as it makes no distinction between different types of intervening habitats, whereas the subjective mapping is based on the assumption that cultivated fields, high sheer cliff,s and riparian areas represent more formidable barriers tothese butterflies than habitat types which are more like the mapped units in physiographic and floral composition. Maps of the surveyed areas also indicate polygon units that may contain antelope brush although that species is not part of the defining description of the units. These include WB, WS, PS, SS, SW and SN map units. In addition to the mapping provided by Harper et al (1996) Sarell et al (2001) identified polygons which they found

2 to be antelope brush dominant, although they had been otherwise identified in the mapping by Harper et al .

Results The west side of the Okanagan drainage system is characterized by a more fragmented distribution of habitat units mapped as containing antelope brush, as well as having a much smaller area of these units (see maps 1a & 1b). Based on the admittedly incomplete sampling accomplished to date, the populations of Behr’s Hairstreak are also more fragmented on the west side. Fig 1. below, shows the distribution of minimal distances over 1km between Behr’s sightings. The largest 4 distances between observations are all on the west side and average 8.8km whereas the largest 4 on the east side average 4.8 km. The larger number of smaller distances on the east side of the valley reflects more intensive sampling there.

Distances over 1km between Behr's Hairstreak Sightings on the East and West Sides of the Okanagan Drainage

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12 10 West side 8 distances (km)

km 6 East side distances (km) 4 2 0 1 3 5 7 9 11 rank order

Fig 1.

The distances between the areas identified as habitat islands are also greater on the west than on the east side of the valley’s drainage system (fig 2.)

3 Minimum distance between polygons mapped as containing Antelope Brush in adjacent Habitat Islands 5 4.5 4 3.5 3 2.5 Km 2 1.5 West side gaps 1 (km) 0.5 East side gaps 0 (km) 1 3 5 7 9 11 Rank Order

Fig 2.

Fifty two survey locations were visited during the study. Named locations, times, number of observers, Behr’s seen, and estimated encounter rates can be found in Appendix II. Table 1 presents a summary of the location data with locations assigned to high, moderate, low, and empty, abundance classes. The table shows that high and moderate abundance classes are found disproportionately on the east side of the valley, low abundance classes were essentially proportionately found on either side, and the number of empty locations were concentrated on the west side of the valley. The only high abundance location found in this survey was that at the Aquila site in the Vaseux Creek Floodplain Habitat Island (see map 1b). Other historically high populations such as those observed by Guppy (pers comm. M. Sarell) and Threatful (pers. comm..,not mapped) are also located on the east side of the valley. Both should be resampled although it appears that the latter, adjacent to Inkameep Provincial Park, was burned this spring. Only the Vaseux fire is shown on the present maps and other recent fires should be indicated on the habitat maps in order to represent more accurately the present availability of Behr’s habitat and the degree of connectivity. On the west side of the valley the populations ranked moderately high are those at the Osoyoos Desert Centre and the adjacent Field’s Lease Ecological Reserve both of which have been assigned to the West Osoyoos Habitat Island –the southernmost of the west side habitat island groups. All sampled sites to the north on the west side of the valley were ranked as either empty or as low abundance populations.

4 Table 1. Sampling Areas Assessed by Behr’s Populations Found on East and West Sides of the Valley

Behr’s Density (Be/ob/hr) East Side of Valley West Side of Valley Totals High (>6Be/ob/hr) 1 1.9% 0 0% 1 1.9% Moderate(>2- =6 Be/ob/hr) 5 9.6% 2 3.8% 7 13.5% Low (<2>0 Be/ob/hr 13 25.0% 7 13.5% 20 38.5% Empty (no Behr’s) 7 13.5% 9 17.3% 16 30.8% Not classified 4 7.7% 0 0% 4 7.7% Combined surveys 4 7.7% 0 0% 4 7.7% Totals 34 65.4% 18 34.6% 52 100%

The following part of the report examines each of the identified habitat islands and makes some suggestions for future surveys based on our current tentative knowledge base. Approximate areas where future surveying is required are indicated on maps 1a and 1b by labeled asterisks (eg E1, W3). Labels identify east (E) or west side(W), and are numbered from south to north. Habitat Island Descriptions and Recommendations for Future Surveys

East Side of the Valley

1) East Osoyoos Habitat Island This patch of habitat lies mainly to the south of highway 97, adjacent to and to the west of Veronica Lake. An old record exists for the area but it has never been thoroughly surveyed and should be included in future. 2) East Osoyoos-Gallagher Lake Habitat Island This is the largest area of contiguous antelope brush habitat remaining in the Okanagan. Several areas within this region remain unsampled. Sites E3,E5 ,E6 and E7 should be surveyed for this reason and to establish whether the existing populations are effectively isolated from one another, or are part of a more continuous distribution. Site E2 is the place where Guppy found a very high density of Behr’s Hairstreaks nectaring on an exotic clover ( Melilotus sp) in the 1990’s. This site should be given a high priority for re- sampling in order to determine whether it still supports a high population of the species, and if so, to evaluate what habitat features are associated with the high densities of Behr’s Hairstreak. Site E4 includes the Haynes Lease ecological reserve and SOWMA properties. The one Behr’s sighting here in 2003 is questionable. The historic records indicate there was a population here in the past but it was at best a low-density colony. The site should be re surveyed to confirm whether or not a low density Behr’s population remains extant at the site. This site is also remarkable for the abundance of California Hairstreaks found here. Comparison of this site with those where Behr’s is the dominant Satyrium species may offer clues to differing ecological requirements of the two species. Sampling at E3, E5 and E4 should be useful in establishing the extent of isolation between populations lying to the north and south.

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3) Vaseux Creek Floodplain Habitat Island This habitat island had by far the highest total number, and highest number of sightings per person-hour, found in the 2003 survey. It appears that comparable colonies of Behr’s Hairstreak existed at the OIB site surveyed by Guppy and at the site adjacent to Inkameep Park reported by Threatful, however most of the latter site burned this year and neither site has been assessed in recent years. Besides the high density of Behr’s Hairstreak at the site, the Vaseux Creek Floodplain is also strategically located. This is the only place in the valley where habitats supporting antelope brush on east and west sides of the drainage system come into such close proximity. This site, and the adjacent Secrest habitat island are therefore key locations for maintaining the existing level of east-west connectivity of arid habitats in the valley. The West Vaseux habitat island is more distant but also may contribute significantly to connectivity. The Vaseux Creek Floodplain is also a key location determining the degree of north-south connectivity on the east side of the valley. The habitat gaps between Vaseux Creek and the habitats to the north and south are problematic and should be investigated further. The small polygon of antelope brush habitat immediately north of Gallagher Lake is largely compromised by the subdivision development, and by ingrowth of ponderosa pine. This area should be surveyed to determine whether there is any remaining habitat connection to the East Osoyoos – Gallagher Habitat Island suitable for Behr’s Hairstreak. There is also a finger of antelope brush dominated habitat which approaches the Vaseux Creek Floodplain Habitat Island from the east running northward behind Gallagher bluff. This polygon terminates approximately where the existing powerlines climb out of the valley. This area should also be surveyed to determine whether Behr’s Hairstreak occurs throughout this potential corridor. Finally the potential connection corridor to the north joining the East Vaseux- Skaha Island should be surveyed. A sighting of Behr’s Hairstreak was recorded this summer from this gap. The north end of the Vaseux Creek Floodplain Habitat Island itself should also be surveyed, as this area was not covered by the 2003 field work. 4) East Vaseux-Skaha Habitat Island This area has been severely impacted at its south end by the Vaseux fire this summer. The area was sparsely surveyed this year and the northern half of the region was not surveyed at all but contains scattered historic records. Future surveys in this habitat island should assess whether scattered antelope brush and Behr’s Hairstreak have survived in the fire-affected area, and sample for suitable habitat and butterflies in the north half of the island.

West Side of the Valley

5) West Osoyoos Habitat Island This habitat island is a loose collection of suitable polygons, some of which support Behr’s Hairstreak populations. Sampling should be carried out at areas W1, W2, and W3 as these sites have likely never been surveyed. 6) West Oliver Habitat Island The West Oliver Habitat Island is a collection of fragmented habitats isolated from the West Osoyoos group by a substantial gap. This archipelago of apparently suitable habitat is very sparsely populated and several polygons may in fact be empty. The northern

6 polygons (W5) should be sampled. To the north Seacrest Habitat Island is relatively close but is either empty or very sparsely populated. If both areas are empty the gap between extant populations is quite substantial. 7) Seacrest Habitat Island No Behr’s Hairstreaks have been found in this habitat area during surveys conducted in 2002 and 2003. Much of the habitat is very xeric, contains few nectar sources, and has considerable pine ingression. The extreme northern tip of the area, where it lies just across the Okanagan River from the Behr’s-rich Vaseux Creek Floodplain, has apparently never been surveyed. This area and those adjacent to the Rattlesnake Lake Basin and the West Oliver Habitat Islands should be resurveyed for both habitat suitability and presence of Behr’s Hairstreak. 8) Rattlesnake Lake Basin Habitat Island The Rattlesnake Lake Basin contains little mapped antelope brush habitat but two records were obtained in this area in the 2003 survey. The area needs to be sampled further both to better assess the Behr’s Hairstreak populations and to evaluate habitat suitability. It would be useful to know whether there is suitable connectivity with the Secrest Habitat Island to the east or west side of the extensive barrier represented by Covert farms. The northern boundary is drawn rather close to the West Vaseux Habitat Island to which it should perhaps be joined if the intervening habitat appears to support connectivity. 9) West Vaseux Habitat Island Although we currently lack an estimate of sampling effort in this habitat island the absence of any positive records from this site in 2003 and the single past record implies that this site is at best sparsely populated. A short but probably effective barrier of unfavorable habitat, including partial intersection by highway 97, the Okanagan River, and cultivated fields, interrupts the connection with the high-density population at Vaseux Creek Floodplain. A similar situation obtains at the north end of the habitat island between the eastern and western sides of the valley. The Vaseux-Skaha Gap appears to be a barrier of a little over 2km of habitat devoid of antelope brush. 10) West Skaha Habitat Island This region was not sample in 2003. The southern tip of the region has been monitored for Behr’s Hairstreak by the author for over 10 years without a positive sighting. There are however two historic records from the northern section of the area. Both these records are in habitats where the antelope brush is heavily ingrown with pine. The area should be surveyed, as it has never been systematically examined.

Discussion

Analysis based on habitat mapping, distance between sighting locations, and Behr’s’ density estimation, all point to the conclusion that the west side of the valley is more fragmented with respect to both the butterfly and its habitat, and that Behr’s Hairstreak numbers are much lower there. Further surveys are required to assess the reality of apparent gaps in suitable habitat and Behr’s’ populations. Evaluation of the connectivity of the Vaseux Creek Floodplain site, which possesses the only currently known high- density Behr’s population, should be given a high priority. Isolated habitat patches containing antelope brush exist to the north of the area surveyed thus far, and at higher elevations adjacent to the present study boundaries. Both should be

7 surveyed for presence of Behr’s Hairstreak in order to better assess the effects of isolation and the elevational and geographic boundaries within which Behr’s is confined.

Future research initiatives should include microclimate monitoring of selected sites differing in density of Behr’s Hairstreak, where these differences are not apparently explicable by reason of geographic isolation or nectar source availability. Research should also be directed at the potential role of ants in determining habitat quality.

Another factor, which may contribute to habitat quality for Behr’s Hairstreak, is the availability of water in the form of moist soils. Although Behr’s is not known to be a “puddling” species, David Threatful has observed this behavior. It may be significant that the Vaseux Creek Floodplain site, and the historical sites of high abundance of this species, were all in areas where a source of soil moisture was part of the colony site. Launer et al (1993) have observed another non-puddling species taking moisture from the banks of a seasonal creek during a drought year. Presence of such moisture resources may be critical here in dry summers, and access to “emergency” moisture sources may permit a habitat to support higher populations. Diversity in soil moisture could also provide some insurance of availability of nectar sources. Other things being equal, in the absence of surface open water, topographic diversity ought to be associated with diversity of soil moisture conditions within a habitat area, and also with microclimate diversity in wind velocity and availability of cover. McLaughlin et al (2002) have shown that topographic diversity buffered populations against weather-induced mortality, reduced population variability, and increased the persistence time-to-extinction of colonies of the Bay Checkerspot butterfly. Fleishman and MacNally (2002) also found that butterfly diversity was strongly related to topographic heterogeneity. It may be useful to investigate how much these factors correlate with Behr’s abundance and it may be prudent to consider such factors in any attempt to establish a new colony site.

Many of the sites containing antelope brush as a dominant component of the environment may be incapable of sustaining viable populations. It is possible that the butterfly does not recognize the unsuitability of these habitats, since the landscapes in the Okanagan have been radically affected by factors such as grazing and the arrival of exotic plants species (Cannings et al 1998). In this case, such habitats may represent “ecological traps”, or “sinks”, and have a detrimental effect on the species survival in this region (Kokko & Sutherland 2001, Keitt et al 2001)), and on its ability to colonize nearby suitable habitats. Potential ecological traps may be sites, lacking sufficient nectar sources, or possessing extremely transient, but highly attractive, nectar sources (eg sumac) but lacking nectar sources which are generally available throughout the flight period (eg yarrow). Orchard verges, which may be attractive because of nectar sources, or soil moisture, may also be traps if insecticide residues adversely affect butterflies drawn to them. Paul Hammond (1995) has argued that butterflies and their larval foodplants can be used as bio-indicators of healthy and diverse ecosystems, as they are relatively easy to monitor cheaply, and with a minimum of training. Kerr et al (2000) demonstrated that butterflies could be used to predict richness of Hymenoptera in the highly fragmented oak savannahs of southern Ontario, which supports the suggestion that they are good

8 candidates as an indicator taxon. Some consideration should be given to carrying out such an ecosystem monitoring study on selected Behr’s and California Hairstreak habitats, and perhaps in other habitats known to be occupied by species of concern (eg White Lake area for the Sooty Hairstreak, Satyrium fuliginosum (W. H. Edwards, 1862)).

PART 2. Mark Recapture Study By Dennis St. John and Sarah Bunge Introduction

A preliminary mark-release-recapture MRR study was initiated in 2003 in order to assess the feasibility of conducting this type of work using this species at the Osoyoos Desert Centre. With individual-specific marking it is possible to obtain data relating to daily vagility, within and between patch movements, estimates of residence time (an estimate of lifespan), standard area of activity (a measure of home range), immigration and emigration rates, and population size and density (Arnold & Powell 1983, Gall 1986). These population parameters are important because vagility and migration rates largely determine rates of colonization and may also affect extinction risks in local populations (Walberg et al 2002). Fragmentation of natural habitats is a matter of serious concern in the Okanagan because of human population pressure and the rapid expansion of intensive agriculture-especially vineyards. Fragmentation has more serious consequences for sedentary butterflies since they are less likely to re-colonize empty habitat patches after local extinction events (Baguette et al 2000). No data are available regarding the mobility, or any other population parameter for Behr’s Hairstreak, however comparative work on other butterfly species suggests that Lycaenids as a group are rather sedentary (Ricketts 2001, Baguette et al 2000, Arnold & Powell 1983, Scott 1975). If this is true of Behr’s Hairstreak this butterfly may be relatively sensitive to fragmentation of habitat. An increase in the distance between suitable habitat patches may render the butterfly unable to re-colonize empty patches, thus compromising overall population viability and metapopulation structure. The loss of high quality habitats, currently supporting healthy Behr’s Hairstreak populations, may also reduce numbers at less favourable sites by removing a source of immigrants and making low population sites vulnerable to local extinction through Allee effects (Keitt et al 2001). Many sites currently empty, or occupied at low density, may in fact lack the habitat features necessary to support a viable population. Any assessment of the vulnerability of Behr’s Hairstreak will require some knowledge of the species’ mobility and population structure.

Methods

Behr’s Hairstreak butterflies were captured and marked at the Osoyoos Desert Centre over a 17 day period from June 18 th through July 4 th . A large mesh net (courtesy Orville Dyer) was used so that butterflies could be marked through the net mesh without directly handling the butterfly. Marks were in the form of dots using different colours of “Sharpie” permanent ink fine point felt marking pens. Up to five marks were placed on the left hind wing using up to three different colours allowing individual coding of each

9 marked . Dot patterns were recognizable when butterflies were closely approached obviating the need to physically recapture the animals in order to identify individuals. Marked animals were released near their capture site within minutes of initial capture. Population estimates were made using the Lincoln Index method with Bailey’s correction for continuity (cited in Gall 1985). The calculations were made using: N= n1(n2+1)/(m+1) with VARN=n1(n2+1)n2-m)/((m+1)(m+2)), where: n1=number of previously marked animals assumed to be alive on day t n2=total number of animals sighted on day t m=number of previously marked animals seen on day t N=total population size on day t VARN=variance of N

Results

A total of 63 butterflies were marked during the course of the study. There were a total of 154 observations not including multiple sighting of the same individual during the same day (fig 3). The sampling effort was unfortunately very uneven over the course of the study. Most of the re-sightings were made on the day following marking and much of the marking was done in the last days of the study. It was therefore not possible to obtain a meaningful estimate of average residence time. However 4 individuals were recaptured at 6,7,7 and 8 days after original marking. A total of 17 individuals were re-sighted on days following marking. Of these 2 were marked and re-sighted at the horsebrush site, 14 were marked and re-sighted at the yarrow garden, and one individual (5.8%), originally marked at the horsebrush site, was later sighted at the yarrow garden. These two sites were estimated to be about 500m apart and this single observation provides the only information we have concerning movements of these butterflies. Inconsistent sampling also vitiated population estimates. Population estimates were made for days with more than 1 re-sighting per day by assuming that all previously marked animals remained in the population. This is totally unrealistic given the short lifespan of these animals and leads to an overestimation of the size of the population. The calculation for 17b was made using only animals known to be alive and present the previous day to estimate the total number of marked animals. This assumption leads to an underestimate of the population size if the pool of marked animals in fact was larger.

10 Behr's Hairstreak Mark-Recapture Data

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30 Subsequent Day 25 Resighting Same Day 20 Resighting 15 Unmarked Number Sighted 10 Number Marked 5

0 1 4 7 10 13 16 Days

Fig. 3

Day of study Estimated population size Standard Deviation 10 58.6 8.56 14 117.0 11.17 15 185.3 23.6 16 292.5 39 17a 185.5 19.9 17 b 52.5 10.6

Table 2. Modified Lincoln Index Population estimates.

Thus estimates of the population size on day 17 ranges between an underestimate of 52.5 and an overestimate of 185.5. Without estimates of mortality, eclosion rates, and immigration/emigration rates it is not possible to infer the total yearly adult butterfly population at the Desert Centre site.

11 Percentage of observation periods an individual was observed nectaring

60

50

40

July 3rd %

% 30 July 4th %

20

10

0 1 2 34 5 6 78 910 Rank

Fig 4

On days 16 and 17, the 3 rd and 4 th of July, observations were made in the yarrow garden throughout most of the day. All marked butterflies were recorded on 17 inspection rounds on the 3 rd and 34 rounds on the 4 th . Figure 4 shows the percentage of observation rounds on which a marked butterfly was re-sighted using those animals that had been marked on a previous day. First butterfly sightings were made at 10:51 on the 3 rd and 10:59 on the 4th and continued until the last sightings of the day at 15:26 and 16:05 respectively. By assuming the number of sightings is a reasonable estimate of time spent nectaring, the percentages in fig 4 can be taken as estimates of the time individuals spent nectaring at the garden. Combining the average percent data from both days yields an average of 17% of the time during the observation period spent nectaring at the yarrow garden. This is equivalent to an average nectaring period of roughly 54 min. Median percentage is 11.8% corresponding to a median nectaring time of 39 minutes. Standard errors were not calculated due to the paucity of data and the fact that nectaring times were definitely not normally distributed, with short times being heavily represented. The relatively long time spent nectaring by some individuals (55. 9% corresponding to ~3 hours in one case) suggests that yarrow inflorescences may serve other functions than providing a nectar source. Males may use the flowers to await potential mates.

12 Discussion

The study carried out in 2003 was to my knowledge the first mark-recapture (re-sight) study undertaken on this species, and is one of a very few attempted on a hairstreak butterfly (subfamily Theclinae). The small size and delicate wings constrain the type of marks which can be applied. The present work established that it is possible to individually mark a number of butterflies with marks that can be fairly easily recognized in the field without the necessity of re-catching the butterfly. As catching and handling the animals is likely to affect both their behavior and longevity (Murphy 1988) the fact that re-catching for identification is unnecessary is very desirable. Unfortunately the sex of individuals this species can generally not be determined without inspection of the dorsal wing surface, which has distinct dark andreconial patches near the forewing costa in the male. The ground dorsal wing colouration is also a darker tawny orange in the male (Kondla 2003). This means that more handling than is necessary for marking would need to be carried out for sex determination. It is clear from all field studies conducted this summer that the overwhelming majority of observations were of animals perching on inflorescences. While this may mean that the animals themselves spend a majority of their time there, it seems likely that these butterflies are also much more detectable when perched on flowers than on the antelope brush shrub. This presents difficulties in adequately detecting daily movements from analysis of mark-recapture data. In this respect the spatial concentration of favoured nectar sources at from 1-3 locations (depending on blooming times) at Desert Centre may result in an atypical distribution of apparent movement and spatial utilization.

Recommendations

1. I believe the place chosen for future work should support a higher density of Behr’s Hairstreak and should have nectar sources distributed more evenly throughout the habitat. On the basis of current knowledge that restricts the choice of study site to the Vaseux Creek Floodplain. 2. I also recommend that at least one, and preferably two people, be funded to conduct the mark recapture study full time, and that the study duration be at least 28 days in order to more fully encompass the species’ flight time and secure estimates of residence time( a proxy for adult lifespan). 3. A flagged grid and should be laid out and the distribution of yarrow mapped just prior to the Behr’s Hairstreak flight season. It may be possible to use GPS mapping for this phase. In any case animals captured in different habitat patches should be given different colour codes. The study grid should be well enough marked to permit the field worker to assign codes at the time of capture.

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Acknowledgments Allison Haney produced the habitat mapping, and she and Mike Sarell offered valuable advice and assistance throughout the project. Sarah Bunge observed and marked butterflies at the Osoyoos Desert Centre. Orville Dyer, Lanelle Parchomchuk, Wilma Corveau, Andrew Frank, and Joanne Muirhead also provided data for the mark recapture study. Many people participated in the “Behr’s Blitz” survey effort. Ron and Roger Hall, Ron’s sons Kx and Kyle, and Crystal Anderson from the Osoyoos Indian Band carried out several surveys on the band lands. Other individuals participating in the field work include: William Alcock, Sue(Eagle Eyes) Austen, Rob Bennett, Andy Bezener, Ron Buechert, Anthea Bryan, Alan Carswell, Neil Dawe, Lora Dingle, Orville Dyer, Jamie Fenneman, M. Giesbrecht, Allison Haney, Jennifer Heron, Kathy Holm, Steven Hureau, Carl McNaughton, Peter Ord, Ryan Price, Jennifer Picker, Mike Sarell, W. Westmoreland, Bryn White, Susan Wood, and someone named Kim.Funding for the fieldwork was arranged by Steven Hureau of Canadaian Wildlife Service, and Jennifer Heron of the Terrestrial Ecosystem Science Section, Biodiversity Branch of the Ministry of Water, Air, and Land Protection through their respective agencies. Funding for the data analsis and report was provided by Aquila Networks Canada Inc arranged by Mike Sarell of Ophiuchus Consulting. Jennifer Heron Orville Dyer and Bryn White coordinated the project, which was supported and initiated by the South Okanagan Invertebrate Recovery Action Group.

References

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Cannings, R. J., E. Durance, and L. K. Scott. 1998. South Okanagan ecosystem recovery plan. Scientific assessment. Unpub. Man. BC Ministry of Environment, Lands and Parks. 108 pp

Fleishman, E., and R. MacNally. 2002. Topographic determinants of faunal nestedness in Great Basin butterfly assemblages: Applications to conservation planning. Cons.

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Appendix I Ecosystem Polygon Descriptions

source: Lea et al. 1991

Ecosystem Unit Description AE Antelope-brush - evening-primrose southerly aspect, coarse sand AN Antelope-brush - needle-and-thread grass coarse-textured soils PA Ponderosa pine - antelope-brush coarse-textured soil PS Ponderosa pine - selaginella shallow soil SN Big sagebrush - needle-and-thread grass coarse-textured soil SS Big sagebrush - selaginella very shallow soil SW Big sagebrush - bluebunch wheatgrass mesic WB Bluebunch wheatgrass - Sandberg's bluegrass deep soil WS Bluebunch wheatgrass - selaginella shallow soil

Appendix II Sampling locations, sampling effort and encounter rates

N Sampling Locations Time Ob Total Min Behr's Be/ob/hr Aquila dyke Aquila Substation Aquila Substation Property combined BC Hydro island in Ck 270 3 810 125 9.26* BETWEEN FIELDS LEASE, OSOYOOS DUMP AND OSOYOOS DESERT CENTER 53 4 212 4 1.13* DRY GRASS SOUTHEAST SADDLE 78 3 234 7 1.79* DRY GRASS SOUTHEAST SADDLE 43 4 172 3 1.04* DRY GRASS WEST FEEDLOT 32 1 32 2 3.75* EAST OF OSOYOOS AIRPORT 124 3 372 1 0.16 EAST SLOPES ABOVE RATTLESNAKE 65 3 195 5 1.54* FAIRVIEW TOWNSITE 85 2 170 0 0 FAIRVIEW TOWNSITE, EAST RESERVE OVERLOOKING OLIVER 18 2 36 0 0 FAIRVIEW TOWNSITE, LOWER SOUTHERN PORTION ALONG OLD GOLF COURSE ROAD 6 2 12 0 0 FAIRVIEW TOWNSITE, NORTH OF TOWNSITE, EAST OF WHITE LAKE ROAD 21 2 42 1 1.43

17 FIELDS LEASE ECOLOGICAL RESERVE 5 4 200 8 2.4 GOLF COURSE combined GOLF COURSE DESERT CENTRE 60 5 300 4 0.8* HAYNES LEASE ECOLOGICAL RESERVE 77 3 231 0 0 Haynes Lease E. Res. East of Blk Sg Rd but not below Throne 60 3 180 0 0 HAYNES POINT PARK 28 2 56 0 0 INKAMEEP PARK 33 3 99 4 2.42 'Just S of NE Unit of NWA on TNT lands 4 2 KENNEDY 140 2-3 400 16 2.4 KENNEDY WEST 106 2 212 5 1.4 MICA CREEK 36 4 144 2 0.83 'NE Unit NWA 2 7 NKMEEP CELLARS 23 3 69 2 1.7* NK'MIP DESERT CENTRE LONE PINE BRIDGE 2 3 NK'MIP DESERT HERITAGE CENTRE 127 2 254 9 2.13* OIB 2 5 OIB LONE PINE 73 5 365 10 1.64* OK FALLS HWY 115 3 345 0 0 OSOYOOS DESERT CENTRE not calculated PENDERGRAFT LICENSE BETWEEN DESERT SOC AND FIELDS LEASE 19 5 95 0 0 RATTLESNAKE LAKE 2 1 SE Unit of NWA 1 1 SEACREST 30 1 30 0 0 SLOPES EAST OF OIB SUBDIVISION 23 2 46 3 3.9* SOUTH OKANAGAN WILDLIFE MANAGEMENT AREA, HAYNES BARN 95 5 475 0** 0 SOUTH OKANAGAN WILDLIFE MGMT AREA 95 5 475 0 0 SOUTH OKANAGAN WILDLIFE MGMT AREA LOT 953 65 3 195 1 0.31 SOUTH TESTALINDEN 53 4 212 0 0 TNT PRATT 100 2 200 3 0.9 VASEUX_TNT BROCK PROPERTY 1 0 'W unit of NWA near mouth of small lagoon 2 0 W unit of NWA near N end of large lagoon 2 0 W unit of NWA near spit N Hatfield's Island 2 0 WEST DRY GRASS 110 5 550 2 .22* WEST DRY GRASS MOUNTAIN WALL 120 3 360 1 .17* WEST DRY SADDLE 5 2 WEST OF RATTLESNAKE LAKE 2 1 WILDLIFE RESERVE N. OF TESTALINDEN 35 9 315 3 0.57

* Times calculated from first and last sighting. This underestimates the times and overestimates the encounter rates

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