National Quail Symposium Proceedings Volume 3 Article 6 1993 Population Trends of Quails in North America Kevin E. Church Kansas Department of Wildlife and Parks John R. Sauer U.S. Fish and Wildlife Service Sam Droege U.S. Fish and Wildlife Service Follow this and additional works at: https://trace.tennessee.edu/nqsp Recommended Citation Church, Kevin E.; Sauer, John R.; and Droege, Sam (1993) "Population Trends of Quails in North America," National Quail Symposium Proceedings: Vol. 3 , Article 6. Available at: https://trace.tennessee.edu/nqsp/vol3/iss1/6 This Population Biology is brought to you for free and open access by Volunteer, Open Access, Library Journals (VOL Journals), published in partnership with The University of Tennessee (UT) University Libraries. This article has been accepted for inclusion in National Quail Symposium Proceedings by an authorized editor. For more information, please visit https://trace.tennessee.edu/nqsp. Church et al.: Population Trends of Quails in North America POPULATION TRENDS OF QUAILS IN NORTH AMERICA KEVIN E. CHURCH, Wildlife Research Section, Kansas Department of Wildlife and Parks, Emporia, KS 66801-1 525 JOHN R. SAUER, Patuxent Wildlife Research Center, U.S. Fish and Wildlife Service, Laurel, MD 20708 SAM DROEGE,Office of Migratory Bird Management, U.S. Fish and Wildlife Service, Laurel, MD 20708 Abstract: We used North American Breeding Bird Survey data (1966-91) to estimate distribution, relative abundance, and population trends of quails. Population trends in grassland/shrub birds sympatric with northern bobwhite (Colinus virginianus) were also examined. Northern bobwhite and scaled quail (Callipepl,a squamata) populations have declined since 1966. Rates of decline for these quails have increased during the past decade. California quail (C. califomica), Gambel's quail (C. gambelii), and mountain quail (Oreortyx pictus) populations have been stable over the long-term (1966-91). However, the short-term (1982-91) trend for California quail is positive, whereas Gambel's quail appear to be declining. Patterns in trends indicate similar factors may be negatively affecting breeding populations of grassland/shrub birds throughout the bobwhite's range. We discuss plausible hypotheses to explain population trends and recommend future action. Key words: abundance, Breeding Bird Survey, California quail, distribution, Gambel's quail, mountain quail, North America, northern bobwhite, population trends, quail, scaled quail. Citation: Church, K. E., J. R. Sauer and S. Droege. 1993. Population trends of quails in North America. Pages 44-54 in K. E. Church and T. V. Dailey, eds. Quail III: national quail symposium. Kansas Dep. WildI. and Parks, Pratt. Monitoring abundance and distribution of a METHODS species is basic to wildlife conseivation. As a The U.S. Fish and Wildlife Seivice and the result, most state conseivation agencies conduct Canadian Wildlife Seivice coordinate the BBS species-specific suiveys to monitor nonmigratory which consists of approximately 3,500 routes game populations. However, not all states suivey throughout North America, of which 2,400 are quail populations, and suivey methods frequently conducted each year during June (Droege 1990). differ. Consequently, data are lacking pertaining Routes are 39.4 km, and contain 50 evenly-spaced to the geographic magnitude and pattern of obseivation stops along secondary roads. At each population change associated with each species of stop, obseivers count all birds heard or seen quail throughout its range in North America. during a 3-minute inteival. The total number of The North American Breeding Bird Suivey each species obseived on the route is used as an (BBS) has been conducted in a systematic manner annual index of abundance. throughout North America for >25 years (Droege We used route-regression analysis to estimate 1990). These data provide an opportunity to long-term (1966-91) and short-term (1982-91) measure long-term changes in distribution and population trends (Geissler and Sauer 1990). relative abundance of breeding birds among Composite annual indices of abundance were states, provinces, and physiographic regions. Fur­ determined by estimating year effects from thermore, examining patterns of population residual variation remaining after the trend trends among sympatric species may help to iden­ analysis (Sauer and Geissler 1990). Trends were tify common factors affecting wildlife over large estimated for individual states and physiographic geographic areas. strata (Butcher 1990) where a species was ob­ We analyzed BBS data to describe distribution, seived on > 13 routes. Populations were con­ relative abundance, and population trends of 5 sidered stable when trends did not differ from 0 species of quail in North America. In addition, we (P< 0.10). examined population trends of 2 common raptors We identified a priori a guild of 13 passerines and numerous passerines sympatric with north­ that occupy grassland/shrub habitats within the ern bobwhite. range of northern bobwhite. Then, we compared We acknowledge the conscientious and skilled population trends of the guild within states where efforts of the thousands of volunteers responsible these species were sympatric with bobwhite. We for gathering BBS data. S. Clark and J. S. Taylor used chi-square analyses t.o determine whether provided comments that improved the the percentage of sympatric species that had manuscript. 1 National Quail Symposium Proceedings, Vol. 3 [1993], Art. 6 Quail Populatwn Trends-Church et al. 45 trend estimates <O in a state was significantly This short-term change reflects decreasing <50%. Similarly, for regions where bobwhite populations in the Staked Plains stratum. declined, we determined the percentage of Gambel's Quail. ----Gambel's quail were physiographic strata in which 9 passerines and 2 reported in 5 states (Fig. 4). Arizona has the predators also had declining populations. highest densities. The long-term continental population trend has been stable (Table 2). RESULTS Likewise, populations in the individual states and Quail Populations the Sonoran Desert showed no change. However, the continental trend during the last 10 years was Northern Bobwhite.-Northern bobwhite are negative (-4.6%/year). the most widely distributed (39 states and On­ Mountain Quail.-Mountain quail were ob­ tario) and abundant quail in North America (Fig. served in 3 states (Fig. 5). The highest densities 1). Highest densities occur in Oklahoma, Mis­ occur in California. Both the long- (1966-91) and souri, Texas, Kansas, and Georgia. The continen­ short-term (1982-91) population trends in the tal population has declined (-2.4%/year) since the U.S. have been stable (Table 2). mid-1960's (Table 1). We analyzed long-term trends for 28 states; only in Wisconsin were there Sympatric Species of Northern increasing populations. Five states observed Bobwhite stable populations, and 22 decreased. Similarly, In general, long-term population trends of the we analyzed long-term population trends within grassland/shrub guild (13 passerine species) 28 physiographic strata. Only the Driftless declined where sympatric with northern bobwhite stratum indicated a long-term increasing trend, 6 (Table 3). Specifically, >50% of these species strata were stable, and 21 populations declined. showed declining populations similar to bobwhite The continental population declined over the in 23 of26 states. Of these, 6 states reported>87% short-term (1982-91) at a slightly more ac­ of the passerines were declining (P < 0.10). In celerated rate (-3.5%/year) than that observed for physiographic strata where bobwhite populations the entire time period (Table 1). Populations in 5 were decreasing, each of the 9 sympatric pas­ states increased, and 5 were stable. Populations serines also declined in more strata (>56%) than in 16 of 26 states exhibited population declines. they increased (Table 4). Declines occurred in Likewise, trends were positive for 3 of 25 strata, >72% of the strata for 6 species (P < 0.10). Con­ 6 were stable, and populations in 16 strata versely, red-tailed hawks and great horned owls declined. increased in >70% of the strata where bobwhite California Quail.-California quail are the declined (P < 0.10). second most widely distributed (5 states and British Columbia) and abundant species of quail in North America (Fig. 2). California has the highest densities. The continental population has DISCUSSION been relatively stable since 1966 (Table 2). We Population trends indicate marked long-term analyzed long-term population trends in 3 states declines for northern bobwhite and scaled quail. and 7 physiographic strata. All states and strata The rate of decline has been greater for both had stable populations. However, since 1982, the species during the last 10 years. In comparison, continental population has shown a slightly posi­ long-term trends for more western species appear tive trend (3.2%/year), due primarily to increased stable. Although short-term trends of California abundance of quail in the California Foothills quail are increasing, those for Gambel's quail are stratum. decreasing. Scakd Quail.-Scaled quail were observed in In general, our results concur with independent 5 states (Fig. 3). The highest densities are found estimates of population trends by others. Bren­ in Texas. The continental population declined nan (1991, 1993a) analyzed Audubon Christmas (-3.8%/year) since the mid-1960's (Table 2). We Bird Count data (1960-88) and reported declining analyzed