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HomeMy WebLinkAboutSWP272000(13) MOSQUITO ABATEMENT PROGRAM 1993 SURVEY AND FINAL REPORT Prepared for: The City of Renton Public Works Department 200 Mill Avenue South Renton, WA 98055 Prepared by: Shapiro and Associates, Inc. 1201 Third Avenue, Suite 1700 Seattle, WA 98115 July 1993 Mosquito Abatement Program 1993 Survey and Final Report i TABLE OF CONTENTS Page Introduction ............................................................................................................l StudyArea...............................................................................................................1 Methods...................................................................................................................1 Results .....................................................................................................................5 Discussion..............................................................................................................10 LiteratureCited.....................................................................................................15 List of Tables Table 1 List of Species Common and Scientific Names .......................................6 Table 2 Five-year Summary of Bird Species ..........................................................8 Table 3 1993 Bird Species Observation Summary ................................................9 Table 4 Pitfall and Sherman Trap Captures........................................................11 Table 5 Five-year Summary of Mammal and Herpetofauna................................12 Table 6 Summary of Active Search Observations...............................................13 List of Figures Figure 1 Site Location Map....................................................................................2 Figure 2 Locations of Traps and Bird Observation Stations..................................4 Shapiro and Associates, Inc.May 1993 Mosquito Abatement Program 1993 Survey and Final Report 1 INTRODUCTION This report presents results of the final year of wildlife studies conducted at the Panther Creek wetland complex for the 1989-1993 City of Renton Mosquito Abatement Program.The wildlife census was a condition of the Hearing Examiner decision to uphold the 1989 SEPA determination of nonsignificance mitigated issued by the City of Renton for a five year program. Previous studies were conducted by Shapiro and Associates, Inc. (SHAPIRO) and the Coot Company (1989), Beak Consultants, Inc. (1990 and 1991), and Jones and Stokes Associates (1992).The surveys are intended to assess whether the applications of Altosid (TM) and Scourge have an adverse effect on wildlife species within the Panther Creek wetland complex. Standardized survey protocols were established in 1990 by Beak Consultants, Inc. (by Mark Rector, currently with SHAPIRO), and were followed closely with minor improvements and/or changes during the following three annual surveys (1991 through 1993). Wetland habitats have been described previ- ously for the approximately 65-acre site (The Coot Company, 1989), and in all other annual reports (Beak, 1990, 1991;Jones and Stokes, 1992). Portions of the wetlands are owned by the City of Renton; the remainder are owned by private landowners, including homeowners residing on uplands located east of the wetlands. STUDY AREA The study area is located in the City of Renton in King County,Washington, east of State Route 167 (East Valley Highway), west of Talbot Road, north of S.W. 43rd Street, and south of Interstate 405 (1- 405). (Figure 1). The southern end of the wetland is dominated by dense stands of reed canarygrass (Phalaris arundinacea) with small patches of cattails (Typha latifolia), and willow (Sahx sp.). Additionally, a forested, approximately 5-acre stand dominated by willow, black cottonwood (Populus trichocarpa) and red alder (Alnus rubra) occurs at the southern end of the wetland on alluvial soils surrounding the inlet where Panther Creek enters the wetland. The main body of the wetland extends from the reed canarygrass habitat at the southern end to the Puget Power transmission line crossing in the north. It is dominated by dense cattail stands with isolated willow patches. North of the transmission line crossing, the wetland is primarily forested with dense shrub and tree vegetation layers present. The shrub layer is dominated by salmonberry (Rubus spectabi[is),and the overstory is dominated by willow, black cotton- wood, and red alder. The entire eastern border of the wetland abuts steep,mixed—forest upland slopes with diverse understory vegetation. The interface between the wetland and upland habitats creates a vegetatively and structur- ally diverse zone with high value to wildlife. The western border lies adjacent to SR-167. A steep, narrow (approximately 20 feet wide) slope provides a buffer between the wetland and the highway. METHODS Methods used in this final annual survey were similar to those used in previous years. Survey protocols are discussed in this section and are expanded upon if they were altered for this year's survey. Shapiro and Associates, Inc.May 1993 5 Lake a0 SEATTLE ss Washing;on :.;:::• ..... . ._ EVE[ETr 167 '.. :. ................. RENTON StATTLE 509 •<. i' 599 ..................... BF;EMERTON • ...:................... ......................... 900 ISSAQUAH .................. . SITE 518 • TACOMA ...... SEA-TAC • OLYMPIA .......... 99 >> .............................: id:::........ SITE ........... .... . :::.::•::•::•;::•:;:;:-:;:. ::..: Youngs z WASHINGTON >::::: 509 ........................................ f ..................................... ....:::::::::::::::::::.�::::::::::....%...� �i 516 5 -� ::::::::::::::::.:: `<f x �l >::>:::<.;::;:.;::»:�::»:::::»>::::::>:::.. ,. ,........; AUBURN:, ....... ::.:; Lake18 Dolloff ..................... :\ ..................... ................... ................... 509 ` ....... . ............................ ............... I: .. ;:,••, .. . �. i ;............. a-. :. FEDERAL .. WAY :. ..... 16 D.......... ... DIAMOND ............... ...... .. ..............: .......... .:..................:........ ... ...... 99 :........................ ''•..;'TACQMA•"• ••; KING COUNTY . ...........�`..:........:..: :PIERCE COUNTY 7. i E.. 51 169 i ... '•, i ............ C . 3 ..... .......... •iiiiiii::'''�••• •....; •• ^Tap t i.. ...........• ..................... i..;... .......... .. -.............. ;. . . FIGURE 1 SITE LOCATIONS 0 1'/2 3 MAP Scale in Miles SHAPIRO& PANTHER CREEK WETLANDS ASSMAMuZ 5/99 Mosquito Abatement Program 1993 Survey and Final Report 3 Bird Surveys To assess bird species and relative abundance at the Panther Creek wetland complex,observations were conducted from six stations (first established in 1990). Two stations with unobstructed views of the wetland were located in representative sections in each of the three distinct habitat types (Figure 2). Three 1 S—minute timed observations of bird species present within visual and auditory detectability were conducted from each station from April 27-29, 1993. Bird species, number,direction and distance from observer, and behavior were recorded. Additional variables recorded included date, time, weather, and temperature. Reptiles, Amphibians, and Small Mammals Eighteen pitfall traps (9 inches deep x 8 inches in diameter) were re-established (several had rusted through and were unusable because of high water levels in the wetland) along three transects around the eastern perimeter of the wetland complex (Figure 2).The reduced number of traps used in this year's survey (18 instead of 20) was determined to be insignificant because of the addition of 20 Sherman live- traps around the wetland periphery (see below). The western perimeter of the wetland lies adjacent to SR-167 and was not sampled. Trapping was conducted within the ecotonal area adjacent to each major habitat type in the wetland, with traps placed in the following manner: (a) traps 1 and 2 were located within the southern forested wetland; (b) traps 3 through S were located within the reed canarygrass- dominated habitat; (c) traps 6 through 13 were located along the cattail—upland interface; and (d) traps 14 through 18 were located in the northern forested wetland (Figure 2). To minimize the adverse effects of soil water on the pitfall traps, (i.e. flooding and ejection of the cans due to hydrostatic water pressure), the traps were located immediately above the wet season high water level. Traps were baited with millet seed, and cotton balls were added for bedding material to help prevent trap deaths. The traps were opened on April 26, 1993, and checked each morning between 7 a.m. and 11 a.m., and checked a second time prior to leaving the site, during late afternoon through early evening hours. Traps were closed on April 29, 1993, and removed from the site. Species, sex,reproductive condition,and weight were recorded for each animal captured. Additional variables recorded included date, weather, time and location of capture. All captured animals were marked to distinguish recaptured individuals from newly caught animals, and all animals were released after data were recorded. In addition to pitfall trapping, Sherman live-traps were used to capture rodents within the wetland complex (this procedure was not used in any of the previous annual surveys). Twenty live-traps were placed in representative sections of the wetland (corresponding to pitfall trap locations) and operated from April 27-29, 1993. Traps were baited with millet seed,and cotton balls were added for bedding material to help prevent trap deaths. Four"active" searches also were conducted to assess additional species that may occur at the wetland complex but were not observed during the bird surveys or captured with traps. Active searches were conducted around the perimeter of the emergent wetland area, in forested sections, and in areas where patches of willow and cottonwood extend into the monotypic stands of cattail and reed canarygrass. Searches included looking under debris, under stumps, in submerged vegetation near open water,and in other suitable habitat and included searches for amphibian egg masses. Searches were conducted for 2- hour periods : two following morning trap checks and the remaining two conducted during twilight hours from approximately 6:00 to 8:00 P.M. Data recorded included species, location of observation, time, and date. Indirect methods of inventorying mammal species also were employed to assess their use of the wetland complex. Tracks, burrows, runways, scat, and incidental observations of mammal species were recorded while inventories of other wildlife species were conducted. Shapiro and Associates, Inc.May 1993 N :o g m N Cj PO .P. x x w ;=3 i � :9 (n o' CULVERT E VALLEY RD .. ;m «; s� s FORESTED >''' >::::::::....... S >:;:>:•;:;:;:;:>;:>;: WILLOW- • ::> ::: 1 A FORESTED.. .... ...: ..:;:::;:::::: ;::>:::z:>::::>::>:>;::::>:::>::>::::>>»::>::>::>::»:;;<:::»:: >::>::>:;>;.:<>::>:::..: ::::.:>;• ;.;:.; :.: • ::.:;::::�:: REED..CANARYGRASS:;;:;:;;;:«.>;:;;:« ::>:«:>:> ,, :;. ::: WETLAND. ;. ::::>�s:#::::::. Uco t K TALBOT RD S o Q. C/) N Cn x Cn W a FIGURE 2 LEGEND: Wetland Pitfall Trap/Sherman Live-Trap LOCATION OF TRAPS AND BIRD OBSERVATION STATIONS E Minnow Trap Bird Observation Station Not To Scale SHAPIRO& PANTHER CREEK WETLANDS ASSM6J ESQ 5/93 Mosquito Abatement Program 1993 Survey and Final Report 5 Aquatic Species Surveys for the presence of aquatic species in the wetland were concentrated in three areas and were conducted following morning trap checks concurrent with "active" searches. The first area, located at the far southern end of the wetland, concentrated on Panther Creek and its associated tributaries. Approxi- mately 500 feet of the stream was surveyed down to and including the drainage ditch running along the eastern perimeter of the wetland (adjacent to SR-167). Shallow water habitat to a depth of 0.5 feet was searched visually using polarized glasses. Deeper areas and water underneath streamside vegetation were swept with a fine mesh fishnet. Approximately eight hours of search time was concentrated on aquatic habitat. The second area surveyed extended south from the Puget Power transmission line crossing through areas of open water. Open water areas (up to 3 feet in depth) within the wetland were traversed several times and examined for the presence of fish and other aquatic species. Visibility was poor,and all sampling was conducted using a fine-meshed fishnet. The third survey area extended north from the transmission line crossing into the forested wetland area; similar survey methods were used in this area. Minnow traps also were used to assess aquatic species present within the wetland. The traps were placed in open water areas around the perimeter of the wetland (Figure 2). The traps were unbaited for the first day and then baited with commercial marshmallow fish bait to attract aquatic species. RESULTS All surveys for wildlife within the Panther Creek wetland complex were completed by April 29,1993. Common and scientific names of all species observed during the five annual surveys from 1989 through 1993 are presented in Table 1. Birds Results of bird surveys indicate a similar number of bird species recorded for the wetland complex during all five annual surveys (Table 2). A low of 21 species were detected in 1992, and a high of 29 species were detected in 1991. Fluctuation in bird species richness (i.e.,number of species) throughout all surveys is not an unusual variation and is expected to occur because of a number of random factors, including time of year, time of day,observer, weather conditions, seasonal variation, and road noise. (Bird surveys at the Panther Creek wetlands were greatly affected by road noise, making it difficult to detect bird calls and interfering with the observer's ability to distinguish species.) During the 1993 survey, 26 bird species were detected during timed observations within the Panther Creek wetland complex (Table 3). The highest number of species (18) were recorded in the willow— cattail dominated habitat at the southern end of the wetland. The reed canarygrass (17) and forested (15) habitat types yielded similar numbers of species. Red-winged blackbird, house finch, song sparrow, and bushtit were the most abundant species detected in the reed canarygrass habitat type. Red-winged blackbird and marsh wren were most common in the willow-cattail area, and song sparrow, black-capped chickadee, and bushtit were most abundant in the forested habitats (Table 3). As in previous surveys (Beak, 1990 and 1991;Jones and Stokes, 1992), red-tailed hawks were frequently heard and observed at the wetland. An apparently active nest was observed during this survey (an adult was seen sitting on the nest while another circled overhead). The nest is located about 200 feet north of bird station 6 at the north end of the northern forested wetland area. Shapiro and Associates, Inc.May 1993 Table 1. Common and Scientific Names for Species Observed at the Panther Creek Wetland Complex during the Five-Year Study Period from 1989 through 1993 COMMON NAME SCIENTIFIC NAME BIRDS American Bittern Botaurus lentiginosus American Coot Fulica americana American Kestrel Falco sparverius American Robin Turdus migratorius Bald Eagle Haliaeetus leucocephalus Barn Swallow Hirundo rustica Bewick's Wren Thryomanes bewickii Black-capped Chickadee Parus atricapillus Black-headed Grosbeak Pheucticus melanocephalus Brown Creeper Certhia americana Brown Headed Cowbird Molothrus ater Bushtit Psaltriparus minimus Canada Goose Branta canadensis Cedar Waxwing Bombycilla cedrorum Common Crow Corvus brachyrhynchos Common Yellowthroat Geothlypis trichas Downy Woodpecker Picoides pubescens European Starling Sturnus vulgaris Evening Grosbeak Coccothraustes vespertinus Fox Sparrow Passerella iliaca Gadwall Anas strepera Great Blue Heron Ardea herodias Green-winged Teal Anas crecca Hairy Woodpecker Picoides villosus House Finch Carpodacus mexicanus House Sparrow Passer domesticus Killdeer Charadrius vociferus Mallard Anas platyrhynchos Marsh Wren Cistothorus palustris Northern Flicker Colaptes auratus Northern Harrier Circus cyaneus Northern Rough-winged Swallow Stelgidopteryx serripennis Red-eyed Vireo Vireo olivaceus Red-tailed Hawk Buteo jamaicensis Red-winged Blackbird Agelaius phoeniceus Ruby-crowned Kinglet Regulus calendula Rufous-sided Towhee Pipilo erythrophthalmus Song Sparrow Melospiza melodic Table 1. Continued COMMON NAME SCIENTIFIC NAME BIRDS (continued) Steller's Jay Cyanocitta stelleri Swainson's Thrush Catharus ustulatus Tree Swallow Tachycineta bicolor Varied Thrush lxoreus naevius Western Flycatcher Empidonax difficilis Western Wood-pewee Contopus sordidulus White-crowned Sparrow Zonotrichia leucophrys Willow Flycatcher Empidonax traillii Wilson's Warbler Wilsonia pusilla Winter Wren Troglodytes troglodytes AMPHIBIANS AND REPTILES Common Garter Snake Thamnophis sirtalis Ensatina Ensatina eschscholtzi Northwestern Salamander Ambystoma gracile Pacific Giant Salamander Dicamptodon ensatus Pacific Tree Frog Hyla regilla Red-legged Frog Rana aurora Roughskin Newt Taricha granulosa Western Terrestrial Garter Snake Thamnophis elegans Western-redback Salamander Plethodon vehiculum MAMMALS Deer Mouse Peromyscus maniculatus Domestic Cat Felis cattus Eastern Gray Squirrel Sciurus carolinensis Masked Shrew Sorex cinereus Montane Shrew Sorex monticolus Raccoon Procyon lotor Shrew-mole Neurotrichus gibbsii Skunk Mephitis mephitis Townsend Mole Scapanus townsendii Vagrant Shrew Sorex vagrans Table 2. Bird Species Observed during Annual Surveys Conducted at the Panther Creek Wetland Complex between 1989 and 1993 YEAR BIRD SPECIES OBSERVED 1989 1990 1991 1992 1993 American Bittern X American Coot X American Kestrel X American Robin X X X X X Bald Eagle X Barn Swallow X X X X Bewick's Wren X X X X Block-copped Chickadee X X X X X Black-headed Grosbeak X X Brown Creeper X Brown Headed Cowbird X Bushtit X X X X X Canada Goose X X Cedar Waxwing X X Common Crow X X X X Common Yellowthroat X X X Downy Woodpecker X X X European Starling X X X X X Evening Grosbeak X X Fox Sparrow X Godwall X Great Blue Heron X X X Green-winged Teal X Hairy Woodpecker X X X House Finch X X X X House Sparrow X X X Killdeer X Mallard X X X X X Marsh Wren X X X X X Northern Flicker X X X X Northern Harrier X Red-eyed Vireo X Red-tailed Hawk X X X X X Red-winged Blackbird X X X X X Rough-winged Swallow X Ruby-crowned Kinglet X X Rufous-sided Towhee X X X X X Song Sparrow X X X X X Steller's )ay X X X X Swainson's Thrush X Tree Swallow X X X X Varied Thrush X Western Flycatcher X Western Wood-pewee X X X White-crowned Sparrow X Willow Flycatcher X X Wilson's Warbler X X Winter Wren X TOTAL NUMBER OF SPECIES 24 27 29 21 27 Table 3. Number of Bird Species Observed in Each Habitat Type at the Panther Creek Wetland Complex during Observations from Three Survey Periods Conducted from April 27-29, 1993 Reed Canaryprass Willow/Cattail Forested SPECIES Total Mean/Visit Total Mean/Visit Total Mean/Visit American Robin 8 2.67 5 1.67 3 1.00 Barn Swallow 2 0.67 0 0.00 0 0.00 Bewick's Wren 5 1.67 0 0.00 5 1.67 Black-capped Chickadee 4 1.33 7 2.33 10 3.33 Bushtit 10 3.33 2 0.67 8 2.67 Canada Goose 4 1.33 7 2.33 0 0.00 Common Crow 4 1.33 1 0.33 0 0.00 Common Yellowthroat 6 2.00 1 0.33 0 0.00 Downy Woodpecker 0 0.00 1 0.33 4 1.33 European Starling 8 2.67 3 1.00 0 0.00 Hairy Woodpecker 0 0.00 0 0.00 1 0.33 House Finch 11 3.67 0 0.00 0 0.00 House Sparrow 0 0.00 1 0.33 0 0.00 Mallard 1 0.33 6 2.00 2 0.67 Marsh Wren 9 3.00 9 3.00 0 0.00 Northern Flicker 0 0.00 1 0.33 1 0.33 Red-eyed Vireo 1 0.33 0 0.00 0 0.00 Red-tailed Hawk 0 0.00 1 0.33 3 1.00 Red-winged Blackbird 11 3.67 30 10.00 4 1.33 Ruby-crowned Kinglet 0 0.00 0 0.00 1 0.33 Rufous-sided Towhee 1 0.33 0 0.00 2 0.67 Song Sparrow 9 3.00 7 2.33 11 3.67 Steller's Jay 1 0 33 1 0.33 0 0.00 Tree Swallow 0 0.00 3 1.00 0 0.00 Willow Flycatcher 0 0.00 1 0.33 4 1.33 Wilson's Warbler 0 0.00 0 0.00 2 0.67 Mosquito Abatement Program 1993 Survey and Final Report 10 Most of the other bird species observed during the surveys were infrequently encountered or were inci- dental observations during surveys for other wildlife. Reptiles, Amphibians, and Small Mammals Three amphibian,one reptile, and six mammal species were observed and/or captured at the wetland (Tables 4 and 5). A single western—redback salamander was captured in a pitfall trap in the northern forested wetland. Vagrant and masked shrews,and shrew moles also were captured in pitfall traps (Table 4). Twenty-nine deer mice were captured with the Sherman live-traps and several were captured more than once (43 total captures). Raccoon and skunk sign were observed during"active"searches or incidental observations during other aspects of the wildlife surveys. Raccoon and skunk tracks were found in several locations, and two striped skunks were observed (Table 5). Aquatic Species As in previous years, three—spined sticklebacks (Gasterosteus aculeatus) were the only fish species ob- served within the Panther Creek wetland complex (Table 5). Eight sticklebacks were captured with a fishnet in an approximately 100-meter reach of the unnamed creek upstream of the culvert under SR- 167 at the northwest edge of the northern forested wetland (Table 6; Figure 2). This also was the only location that sticklebacks were observed in the 1992 surveys(Jones and Stokes, 1992). No fish were observed in any other portion of the wetland,however,nor were any captured in minnow traps. Several water beetles were captured with the minnow traps (Family Dytiscidae) and were the only other aquatic species captured. No amphibians were captured in the minnow traps. DISCUSSION The Panther Creek wetland complex continues to possess a diverse array of wildlife species. All species observed during the 1993 survey are common in western Washington and are consistent with wildlife species observed at the Panther Creek wetlands during annual surveys from 1989 through 1992, and in numerous wetlands throughout King County as part of the Puget Sound Wetlands and Stormwater Management and Research Program (West and Rector, 1989). No state or federally listed threatened or endangered species were observed during the survey, and none are reported for the immediate vicinity of the study area (Young, 1993). The results of this year's study, in conjunction with all previous studies, indicate a relatively stable wildlife community, but with a reduced number of aquatic species (three- spined stickleback) captured from previous years. The five-year trend in bird species richness and abundance at the wetland indicates a stable community with no significant change in species composition. As mentioned previously,species number ranged from 21 to 29 species and is within an expected range of variation for natural populations (Southwood, 1978),given survey conditions (see above). Amphibian and aquatic species (three-spired stickleback) populations were infrequently observed in the 1993 survey, compared with the 1991 survey(Beak, 1991). Although several frogs were observed, only one salamander was captured (Table 4). A similarly low number of aquatic species (three-spined stickleback)and amphibians were captured during the 1992 survey (Jones and Stokes, 1992). Shapiro and Associates, Inc.May 1993 Table 4. Small Mammals and Amphibians Captured in Sherman and Pitfall Traps during Surveys Conducted From April 27-29, 1993 SPECIES Sherman Trap Captures Pitfall Trap Captures Western-redback Salamander 0 1 Shrew-mole 0 3 Vagrant Shrew 0 2 Masked Shrew 0 1 Deer Mouse 29 0 Table 5. Mammal, Herpetile, and Fish Species Observed at the Panther Creek Wetland Complex during Annual Surveys Conducted from 1989 through 1993 YEAR SPECIES OBSERVED 1989 1990 1991 1992 1993 AMPHIBIANS AND REPTILES Western-redback Salamander 7 2 0 1 Ensatina X 1 0 0 0 Northwestern Salamander 1 15 0 0 Roughskin Newt 0 5 2 0 Pacific Giant Salamander 0 0 1 0 Red-legged Frog X 5 6 0 1 Pacific Tree Froq X 2 1 5 3 Western Terrestrial Garter Snake X 4 4 3 4 Common Garter Snake X 16 1 0 0 MAMMALS Masked Shrew 0 0 5 1 Montane Shrew 0 1 0 0 Vagrant Shrew 1 0 0 2 Shrew-mole 0 5 0 3 Townsend Mole 1 0 0 0 Deer Mouse 1 9 0 43 Eastern Gray Squirrel 0 0 2 0 Skunk 1 & tracks 1 den 0 2 & Tracks Domestic Cat 0 0 2 0 Raccoon X tracks only tracks only 2 Tracks FISH Three-spined Stickleback Not sampled 4 captured & 33 4 8 many observed in pools Table 6. Species Observed during Active Searches Conducted at the Panther Creek Wetland Complex from April 26-29, 1993 Date Species Number Location 4/26/93 Canada geese 4 Reed canarygrass meadow 4/26/93 American robin 1 Reed canarygrass meadow 4/26/93 Song sparrow 1 Reed canarygrass meadow 4/26/93 Red-tailed hawk 1 Over powerline corridor 4/26/93 Canada geese 4 In willow-cattail habitat 4/26/93 Western redback salamander 1 Forested wetland 4/27/93 Striped skunk Numerous Trails in reed canarygrass meadow 4/27/93 Western flycatcher 1 Near pitfall trap # 4 4/27/93 Downy woodpecker 1 Foraging on snag adjacent to powerline corridor 4/27/93 Garter snake 1 On grass slope adjacent to SR-167 4/27/93 Pacific tree frog 1 Near bird station # 3 4/29/93 Pacific tree frog 2 Near bird station # 4 4/29/93 Red-legged frog 1 Near trap # 19 by small drainage 4/29/93 Garter snake 1 South end of site near blue house 4/29/93 Garter snake 1 Near minnow trap # 2 4/29/93 Garter snake 1 In reed canarygrass meadow 4/29/93 Three-spined stickleback 8 Captured with dipnet in 100-meter stretch of creek upstream of culvert under SR-167 4/28/93 Striped skunk 1 Foraging in reed canarygrass meadow Mosquito Abatement Program 1993 Survey and Final Report 14 The regional drought that occurred during 1992 may have played a large role in the apparent reduction in populations of these species groups. Most open water areas in the wetland dry up each year, and aquatic species (including three-spined stickleback) populations apparently seek refuge in remaining pools until seasonal rains restore water levels that enable the aquatic species to recolonize the wetland. If no,or few, water pools remained at the end of the summer in 1992 (because of the drought), most aquatic species in the wetland would have perished,preventing their successful recolonization of the wetland in 1993, following winter and spring rains. Additional variables that may be a factor in the apparent decline in aquatic species populations within the wetland are discussed in the 1992 annual report (Jones and Stokes, 1992). The Panther Creek wetland continues to be inhabited by a diverse and abundant assemblage of species. Although some fluctuations in species abundance has occurred (reduced number of observed adult amphibians and stickleback fish), the surveys reveal a wildlife community that remains typical for a wetland of this size,degree of isolation from undisturbed habitat, weather conditions, and time of year the surveys were conducted throughout the five-year period. Shapiro and Associates, Inc.May 1993 Mosquito Abatement Program 1993 Survey and Final Report 15 LITERATURE CITED Beak Consultants,Inc., 1990. Final Report of Wildlife Surveys Conducted at the Panther Creek Wetland Complex. Seattle, WA. Beak Consultants,Inc., 1991. Cityof Renton Mosquito Abatement Program 1991 Wildlife Survey. Seattle,WA. Coot Company, The 1989. P-9/Panther Creek Project Wetlands Inventory. Olympia, WA. Jones and Stokes Associates, 1992. Mosquito Abatement Program 1992 Wildlife Survey. Bellevue, WA. Shapiro and Associates, Inc., 1989. Panther Creek Wetland Reptile and Amphibian Survey. Seattle, WA. Southwood, T.R.E., 1978. Ecological Methods with Particular Reference to the Study of Insect Populations. Chapman and Hall Publishers. University Press, Cambridge, England. 524 pp. West,S.D.,and M.E.Rector., 1989. Summary Report:Monitoring Mammalian and Herpetofaunal Populations. Prepared for Puget Sound Wetlands and Stormwater Management Research Program. Seattle,WA. Young,T., 1993. GIS Manager. Priority Habitats and Species Database Search. Washington Department of Wildlife, Olympia, WA. Personal Communication. Shapiro and Associates, Inc.May 1993