172 



IiiverlehniU's — Our Lniiif; Resources 



% counts 



75 77 79 81 83 85 87 89 91 93 95 

 Year 



Fig. 1. Number ot painted ladies 

 ( Vanessa lardui) per count and 

 percentage of counts reporting this 

 species, for all counts in North 

 America north of Mexico. 

 1977-93. 



4,0- 



3.5- 



3.0- 



2.5- 



2.0 



1.5 



1.0 



0.5 



0.0 



Eastern 



I Western 



AL 



77 79 81 83 85 87 89 91 93 

 Year 



Fig. 2. Mean number of mon- 

 archs {Daiunis pk-xippus) per 

 party-hour for counts reporting the 

 species east of the Rocky 

 Mountains. 1977-93. and west of 

 the Rocky Mountains. 1987-93. 



For further iniurmation: 



Ann B. Swengel 



North American Buttertly 



Association 



909 Birch St. 



Baraboo, Wl 5.3913 



subtropical species with a tendency to wander 

 (immigrate) outside its residential range into 

 temperate regions, with periodic years of mas- 

 sive invasions. FJC data clearly reflect this 

 aspect of the species" natural history by show- 

 ing dramatic fluctuations in painted lady fre- 

 quency and abundance in the counts in 1979, 

 1983, and 1992 (Swengel 1993; Fig. 1). These 

 outbreaks may correlate with weather perturba- 

 tions in the species" residential range (Myres 

 1985; Swengel 1993). 



FJC data have also been used to document 

 tluctuations in other immigrant species 

 (Swengel 1990). but especially to monitor pop- 

 ulation trends of the migrant monarch buttertly 

 (Dancnis plexippus: Swengel 1990 and unpub- 

 lished data) that breeds in temperate North 

 America and overwinters in Mexico and coastal 

 California. The number of these butterllies fluc- 

 tuates considerably (Fig. 2); fluctuations tend to 

 correlate with major climatic perturbations such 

 as the El Nifio Southern Oscillation and major 

 volcanic eruptions (Swengel, unpublished 

 data). Monarchs and painted ladies often show 

 dramatic fluctuations in the same years (e.g., 

 1978-79, 1982-83, 1991-92), but usually they 

 vary in opposite directions (Figs. 1 and 2). sug- 

 gesting that the same widespread climatic phe- 

 nomena tend to affect both species in different 

 ways. Because conservationists are concerned 

 about threats to the overwintering habitat of 

 monarchs, long-term data sets such as FJC are 

 valuable to check for persistent downward 

 trends. 



While FJC cannot replace more formal and 

 intensive scientific surveying, it does offer a 



K;imer blue (Lycaeides melissa samuelis) male basking on 



readily available and ever-enlarging data set that, 

 with caution, is useful for science and conserva- 

 tion because of its relative continuity, inexpen- 

 siveness, large size, and widespread sampling. 



References 



Myres, M.T. 198.'i. A southward return migration of painted 

 lady butterllies. Vanessa cardui. over southern Alberta m 

 the fall of 1983. and biometeorological aspects of their 

 outbreaks mto North America and Europe. The Canadian 

 Field-Naturalist 99;147-L'i-'i. 



Nagel, H. 1992. The link between Platte River flows and the 

 regal fritillary butterfly. The Braided River 4: 10-1 1. 



Nagel. H.G.. T. Nightengale, and N. Dankert. 1991. Regal 

 fritillary buttertly population estimation and natural his- 

 tory on Rowe Sanctuary. Nebraska. Prairie Naturalist 

 23:'l45-152. 



Opier. PA., and A.B. Swengel. 1994. NABA-Xerces Fourth 

 of July buttertly counts 1993 report. North American 

 Buttertly Association. Morristown. NJ. 72 pp. 



Swengel. A.B. 1990. Monitoring butterfly populations using 

 the 4th of July buttertly count. American Midland 

 Naturalist 124:.V95-406. 



Swengel. A. 1993. Permutations of painted ladies. Amencan 

 Buttertliesl(2):.34. 



Species 

 Richness and 

 Trends of 

 Western 

 Butterflies and 

 Moths 



by 



Paul A. OpIer 



National Biological Service 



Butterflies and large moths are among the 

 best-sampled insects and as such are excel- 

 lent indicators of ecological conditions or envi- 

 ronmental change. Because the caterpillars of 

 most Lepidoptera are herbivorous, their species 

 richness is most often a reflection of plant diver- 

 sity (Brown and Opler 1990). 



Management or restoration of invertebrate 

 diversity requires comprehensive data about the 

 status and occurrence of species. I present the 

 species richness of butterflies and three moth 

 famihes in the 17 western conterminous states 

 and five smaller subareas in the West. 



Data Collection 



The species richness of western butterflies 

 and moths (Lepidoptera) was determined by 

 using four county-level atlases and counting the 

 number of species recorded in each state or 

 region (Peigler and Opler 1993; Smith 1993; 

 Stanford and Opler 1993; Opler, unpublished 



data). The county atlases were developed by 

 using specimen data from field surveys, private 

 collections, museums, and scientific mono- 

 graphs. The records analyzed include all histor- 

 ical data; thus the map for a particular species 

 may not represent its current status. 



Buttertlies (superfamilies Papilionoidea and 

 Hesperioidea), hawkmoths (Sphingidae), silk- 

 moths (Satumiidae), and tiger moths (Arctiidae) 

 are relatively well-sampled groups and therefore 

 give a good preliminary indication of the geo- 

 graphic patterns of species richness. Populations 

 of the selected butterflies and moths in the 17 

 conterminous western states and five subregions 

 were selected as sampling units. 



The five subregions are the lower Rio 

 Grande Valley of South Texas, the Big Bend 

 region of Texas, the Colorado Front Range, the 

 isolated mountains of southeastern Arizona and 

 adjacent New Mexico (the so-called "sky 

 islands"), and southern California south of the 

 Transverse Ranges (Fig. 1 ). They were selected 



