Southwestern Naturalist最新文献

{"title":"SECONDARY AND TERTIARY SEX RATIOS IN WHITE-WINGED DOVES (ZENAIDA ASIATICA) IN TEXAS","authors":"Katie A. Moccia, J. T. Baccus, M. F. Small, T. Simpson","doi":"10.1894/0038-4909-66.3.189","DOIUrl":"https://doi.org/10.1894/0038-4909-66.3.189","url":null,"abstract":"Abstract Sex ratio is an important parameter influencing the demography of wildlife species. Sex ratios are categorized as primary (sex at fertilization), secondary (sex at birth through immaturity), tertiary (sex at adulthood), and quaternary (sex at post-reproductive age). Herein, we examined the secondary1 (hatchling), secondary2 (juvenile or subadult), and tertiary (adult) sex ratios of white-winged doves (Zenaida asiatica). Also, because white-winged doves typically hatch two eggs, we also evaluated the secondary sex ratio of co-occurring nestlings. Interestingly, secondary and juvenile sex ratios were significantly male biased, whereas tertiary sex ratios were not biased. Additionally, the ratio of same-sex nestlings was also male biased. The lack of bias at the tertiary level supports Fisher's principle that differential selection for sex ratios of 1:1 exist and lead to more stable populations. Therefore, we conclude that there is some selection mechanism present in this species that selects against males reaching adult status given our findings at the secondary and juvenile sex ratio levels. Resumen La proporción de sexos es un parámetro importante que influye en la demografía de las especies silvestres. Las proporciones de sexos se clasifican en primarias (sexo en la fecundación), secundarias (sexo al nacer/inmaduro), terciarias (sexo en la edad adulta) y cuaternarias (sexo en la edad pos reproductiva). Aquí, examinamos la secundaria1 (cría), secundaria2 (juveniles o subadultos) y terciarios (adultos) de las palomas aliblancas (Zenaida asiatica). Además, debido a que las palomas aliblancas suelen incubar dos huevos, también evaluamos la proporción de sexos secundarios de los polluelos coexistentes. Curiosamente, las proporciones de sexos secundarios y de juveniles fueron significativamente sesgadas por los machos, mientras que las proporciones de sexos en el terciario no lo fueron. Además, la proporción de polluelos del mismo sexo también estaba sesgada por los machos. La falta de sesgo en la proporción terciaria apoya al principio de Fisher, que existe la selección diferencial para la proporción de sexo de 1:1 y conducen a poblaciones más estables. Por lo tanto, llegamos a la conclusión de que existe algún mecanismo de selección presente en esta especie que selecciona para que los machos no alcancen el estado adulto, dados nuestros hallazgos en la proporción de sexos secundaria y de juveniles.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"189 - 192"},"PeriodicalIF":0.2,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43798625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FOREIGN SPIDERS AND INSECTS IN ANELOSIMUS CF. ANALYTICUS (ARANEAE: THERIDIIDAE) NESTS IN THE SONORAN DESERT, MEXICO","authors":"Julio Javier Gastélum-Reyes, María Cristina Peñalba-Garmendia, A. Fu-Castillo, N. Navarro-Gómez, R. Castillo-Gámez, A. Meling-López","doi":"10.1894/0038-4909-66.3.193","DOIUrl":"https://doi.org/10.1894/0038-4909-66.3.193","url":null,"abstract":"Abstract Spiders of the genus Anelosimus are social, subsocial, and solitary. A recent report described one of these species as tolerant to foreign arthropods in their webs. In this study we report the arthropod diversity found in 90 nests of Anelosimus cf. analyticus from the southern Sonoran Desert. We sampled from March 2015 to November 2016 and during January 2017. We separated the nests into small, medium, and large, counting spiders and insects. We also counted females, males, and juveniles of each spider species. We analyzed diversity with and without A. cf. analyticus with the Shannon-Weaver (H′) diversity index and used the equitability index (EPielou) to analyze the similarity of richness between months. We found 48 species inhabiting the nests, and in 67 nests A. cf. analyticus was present along with other species of spiders and insects. Ovisacs and molts of the spider were also frequent. The ensemble of foreign species did not show a consistent pattern of similarity among months, but small and medium sizes showed a low value of similarity. From these results, we consider A. cf. analyticus a subsocial species whose small and medium nests had great activity and species turnover during the months sampled, which did not allow groups of foreign species to establish for more than two consecutive months. Resumen Arañas del género Anelosimus son sociales, subsociales y solitarias. Una de estas especies fue descrita recientemente como tolerante a los artrópodos foráneos en sus nidos. En este estudio reportamos la diversidad de artrópodos encontrados en 90 nidos de A. cf. analyticus del sur del Desierto de Sonora. Muestreamos desde marzo de 2015 hasta noviembre de 2016 y durante enero de 2017. Los nidos se separaron en pequeños, medianos y grandes, contando arañas e insectos. También contamos hembras, machos y juveniles de cada especie de araña. Analizamos la diversidad con y sin A. cf. analyticus con H′ y EPielou, y la similitud de riqueza entre meses. Encontramos 48 especies que habitaban los nidos, y en 67 nidos A. cf. analyticus estuvo presente junto con otras especies de arañas e insectos. Los ovisacos y mudas de la araña también fueron frecuentes. El conjunto de especies foráneas no mostró un patrón consistente de similitud entre meses, pero los tamaños pequeños y medianos mostraron un valor de similitud bajo. A partir de estos resultados, consideramos A. cf. analyticus una especie subsocial cuyos nidos pequeños y medianos tuvieron gran actividad y rotación de especies durante los meses muestreados, lo que no permitió que grupos de especies foráneas se establecieran durante más de dos meses consecutivos.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"193 - 202"},"PeriodicalIF":0.2,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46726727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NEW ASSOCIATION BETWEEN THE VOLE MICROTUS CALIFORNICUS (RODENTIA: CRICETIDAE) AND THE FLEA STENISTOMERA ALPINA (SIPHONAPTERA: HYSTRICHOPSYLLIDAE)","authors":"C. Conroy, K. Padgett, J. Tucker","doi":"10.1894/0038-4909-66.2.170","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.170","url":null,"abstract":"Abstract During mammal surveys at China Lake Naval Air Weapons Station in the Mojave Desert, we found California voles (Microtus californicus) infested with three flea species including the flea Stenistomera alpina. Collected near the eastern edge of the distribution of the vole and the western edge of the distribution of the flea, this is the first record of S. alpina on California voles, indeed on any Microtus species. Resumen Durante muestreos de mamíferos realizados en la Estación China Lake Naval Air Weapons ubicada en el desierto de Mojave, encontramos ratones de campo Microtus californicus infestados con tres especies de pulgas, incluyendo la especie Stenistomera alpina. Al haber sido colectados cerca del límite este del área de distribución de M. californicus y el límite oeste del área de distribución de S. alpina, este es el primer registro de S. alpina en M. californicus y en cualquier especie de Microtus.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"170 - 175"},"PeriodicalIF":0.2,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48991189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GRAY FOX (UROCYON CINEREOARGENTEUS) SPACE USE IN SOUTHEASTERN ARIZONA","authors":"Amanda M. Veals, J. Koprowski, K. Vercauteren, David L. Bergman, M. V. Mazzamuto","doi":"10.1894/0038-4909-66.2.166","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.166","url":null,"abstract":"Abstract Gray foxes (Urocyon cinereoargenteus) are considered a widespread and common species in the southwestern United States, although little is known about their spatial ecology that can inform rabies management strategies. We used data acquired from very high frequency and global positioning system satellite collars on gray foxes in the White Mountains and Pinaleño Mountains of Arizona to assess habitat use, movement patterns, and home range requirements. We present preliminary results from adult gray foxes (n = 3) from a larger study aimed at understanding gray fox space use for zoonotic disease management in the state. Average home range size was 3.78 ± 2.74 km2 (SD) and gray foxes used ponderosa pine forests across both study sites, with individuals also selecting for this vegetation community at the home range scale. Resumen El zorro gris (Urocyon cinereoargenteus) se considera una especie común y con gran extensión de distribución en el suroeste de los Estados Unidos, sin embargo, poco se sabe acerca de su ecología espacial que pueda informar sobre estrategias de manejo de la rabia. Utilizamos datos adquiridos por collares satelitales en zorros grises en las montañas Blancas y las montañas Pinaleño de Arizona para evaluar el uso del hábitat, patrones de movimiento y los requerimientos del ámbito hogareño. Presentamos resultados preliminares de zorros grises adultos (n = 3) de un estudio más amplio dirigido a comprender el uso del espacio del zorro gris para el manejo de la enfermedad zoonótica en el estado. El tamaño promedio del ámbito hogareño fue de 3.78 ± 2.74 km2 (DE) y los zorros grises usaron bosques de pino ponderosa en ambos sitios de estudio con individuos seleccionando también esta comunidad de vegetación en la escala del ámbito hogareño.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"166 - 168"},"PeriodicalIF":0.2,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47321442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EFFECTS OF LANDSCAPE HISTORY ON CURRENT GEOGRAPHIC DISTRIBUTIONS OF FOUR SPECIES OF REPTILES AND AMPHIBIANS IN KANSAS","authors":"W. Busby, N. Barve, M. Cobos, A. Peterson","doi":"10.1894/0038-4909-66.2.157","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.157","url":null,"abstract":"Abstract Distributions of species are frequently treated as responding to current environmental conditions across areas that have been accessible to them. Although that paradigm has been quite successful in describing distributional areas, the effects of land use history have been neglected in most studies to date. In this study, we analyzed effects of historical land use (i.e., 1850s to present) on distributions of four reptile and amphibian species in eastern Kansas. We fit typical species distribution models using a broad diversity of descriptors of landscape and environmental conditions, and detailed model selection exercises in all cases identified a combination of current land use and topographic features as the best defining dimensions for species' distributions. However, within the areas identified as suitable in these modeling exercises, known occurrences of each species were concentrated in areas that had been forested in the 1850s, and that remain forested. That is, although current land use was crucial, land use history was an important modifier, such that distributional ecology must look to more than just current environmental conditions in efforts to characterize species' geographic distributions comprehensively. Resumen Las distribuciones de especies se tratan frecuentemente como si respondieran a condiciones ambientales actuales en las áreas que han sido accesibles para estas. Aunque ese paradigma ha sido exitoso en la descripción de áreas de distribución, los efectos de la historia del uso del suelo han sido descuidados en la mayoría de los estudios hasta la fecha. En este estudio, analizamos los efectos del uso histórico del suelo (i.e., desde la década de 1850 hasta el presente) en las distribuciones de cuatro especies de reptiles y anfibios en el este de Kansas. Ajustamos modelos típicos de distribución de especies usando una amplia diversidad de descriptores de paisaje y condiciones ambientales, y ejercicios detallados de selección de modelos identificaron en todos los casos una combinación de uso actual del suelo y características topográficas como las mejores dimensiones para definir las distribuciones de especies. Sin embargo, dentro de las áreas identificadas como adecuadas en estos ejercicios de modelado, las ocurrencias conocidas de cada especie se concentraron en áreas que habían sido boscosas en la década de1850 y que continúan siendo boscosas. Es decir, aunque el uso actual del suelo fue crucial, la historia del uso de la tierra fue un factor importante, de modo que la ecología de distribuciones debe mirar más allá de las condiciones ambientales actuales en un esfuerzo por caracterizar las distribuciones geográficas de especies de manera completa.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"157 - 165"},"PeriodicalIF":0.2,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47824515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RED SWAMP CRAYFISH (PROCAMBARUS CLARKII) IN THE PECOS VALLEY, NEW MEXICO","authors":"Jeffrey S. Beauchamp, T. Huckaby, William P. Johnson, D. Furr, D. A. Trujillo","doi":"10.1894/0038-4909-66.2.185","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.185","url":null,"abstract":"Abstract Invasive species are a global threat to biodiversity, and their introduction can have large economic and ecological consequences. Red swamp crayfish (Procambarus clarkii) are known to be highly invasive and can alter ecosystem structure and function. We document a recent occurrence of P. clarkii in a Pecos River tributary, New Mexico, following removal of common carp (Cyprinus carpio), another highly invasive species, from recently restored aquatic habitat. Resumen Las especies invasoras son una amenaza global para la biodiversidad y su introducción puede tener grandes consecuencias económicas y ecológicas. Se sabe que el cangrejo rojo del pantano (Procambarus clarkii) es altamente invasivo y puede alterar la estructura y función del ecosistema. Documentamos la aparición reciente de P. clarkii en un afluente del río Pecos, Nuevo México, luego de la eliminación de la carpa común (Cyprinus carpio), otra especie altamente invasiva, del hábitat acuático recientemente restaurado.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"35 12","pages":"185 - 188"},"PeriodicalIF":0.2,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41295335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FACULTATIVE OUTCROSSING INFERRED FROM POLLEN–OVULE RATIOS IN PENSTEMON DEGENERI (PLANTAGINACEAE), A RARE COLORADO ENDEMIC","authors":"Angela Baur, Carol T. English, C. Alba, Audrey Spencer, L. Bruederle","doi":"10.1894/0038-4909-66.2.175","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.175","url":null,"abstract":"Abstract Pollen–ovule ratios can be a reliable indicator of a flowering plant species' pollination strategy and mating system. Here, we quantify pollen–ovule ratios in Penstemon degeneri (Plantaginaceae) and assess population-level variation for this trait. Pollen–ovule ratios were similar, but higher than means reported for other facultative xenogamous species, supporting our hypothesis of a mixed mating system. Variation within and among populations is likely due to environmental variability at these sites. Resumen Las proporciones de polen y óvalos pueden ser indicadores confiables de la estrategia de polinización y el sistema de reproducción de las plantas. Calculamos las proporciones de polen y óvalos de Penstemon degeneri (Plantaginaceae) y evaluamos la variabilidad de éstas a nivel poblacional. Las proporciones de polen y óvalos eran similares, aunque sus promedios eran mayores comparados a los de otras especies de plantas facultativas y alógamas, lo cual confirma nuestra hipótesis de un sistema de reproducción mixto. Es probable que la variabilidad entre una o múltiples poblaciones sea el resultado de la variabilidad ambiental en los sitios correspondientes.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"175 - 179"},"PeriodicalIF":0.2,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44807934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DIET COMPARISON BETWEEN JUVENILE AND ADULT INVASIVE CHANNEL CATFISH (ICTALURUS PUNCTATUS) IN THE SAN JUAN RIVER","authors":"Isabel G. Evelyn, S. C. Hedden, N. R. Franssen, K. Gido","doi":"10.1894/0038-4909-66.2.180","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.180","url":null,"abstract":"Abstract Extensive efforts to reduce the population of invasive channel catfish (Ictalurus punctatus) in the San Juan River, USA, have increased the relative abundance of juveniles, with little understanding about potential trophic interactions between these juveniles and native fishes. Gut contents of juvenile (<250 mm total length) and adult (≥300 mm) channel catfish in the San Juan River were collected in the summer and fall of 2018 and 2019 to quantify ontogenetic change in diet. Juveniles primarily consumed aquatic insects and terrestrial plants, whereas adults primarily consumed fewer aquatic insects and significantly more plants and fish. Logistic regression confirmed these diet shifts as a function of total length and suggest the nature of interactions between channel catfish and native fishes can change with life stage: from potential competitor for aquatic invertebrates, to competitor and predator. Resumen Esfuerzos extensos para reducir la población de bagres de canal invasores (Ictalurus punctatus) en el río San Juan, EE.UU., han aumentado la abundancia relativa de juveniles, con poco entendimiento sobre las posibles interacciones tróficas entre estos juveniles y peces nativos. Los contenidos del estómago de bagres de canal juveniles (<250 mm longitud total) y adultos (≥300 mm) en el río San Juan fueron colectados en el verano y otoño del 2018 y 2019 para cuantificar el cambio ontogenético en la dieta. Los juveniles consumieron principalmente insectos acuáticos y plantas terrestres, mientras que los adultos principalmente consumieron menos insectos acuáticos y significativamente más plantas y peces. La regresión logística confirmó estos cambios en la dieta como una función de la longitud total y sugiere que la naturaleza de las interacciones entre los bagres de canal y los peces nativos puede cambiar con la fase de la vida: de un competidor potencial para los invertebrados acuáticos, a competidor y depredador.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"180 - 184"},"PeriodicalIF":0.2,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45961908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FACTORS INFLUENCING THE DISTRIBUTION OF SUBMERGED AQUATIC MACROPHYTES IN JEMEZ MOUNTAIN STREAMS, NORTHERN NEW MEXICO, USA","authors":"V. F. Thompson, D. Marshall, R. Bixby, C. Dahm","doi":"10.1894/0038-4909-66.2.150","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.150","url":null,"abstract":"Abstract Submerged aquatic macrophytes (SAMs) have been studied extensively in lotic ecosystems at low elevations, but few studies have been conducted in high-elevation systems, and factors controlling SAM distribution at high elevation are not well understood. After anecdotal and published documentation of abundant SAMs in high-elevation streams in the Jemez Mountains, northern New Mexico, USA, we wanted to determine what combination of physical factors are controlling the presence or absence of SAMs in the Jemez River watershed. We surveyed several sites on the three major river systems in the watershed along a gradient of elevation for physical factors, presence-absence, and percent cover of each taxa. Our results showed that SAMs were observed in 60% of surveyed sites that were associated with deeper, narrower, lower-velocity streams with low gradients. This evidence suggests that SAMs at high elevations are subject to similar abiotic controls found for SAM presence at lower elevations. Resumen Los macrófitos acuáticos sumergidos (SAMs, por sus siglas en inglés) han sido extensamente estudiados en los ecosistemas lóticos a bajas elevaciones, pero se han conducido pocos estudios en sistemas de alta elevación y los factores que controlan la distribución de los SAMs a gran altura no son bien comprendidos. Después de la documentación anecdótica y publicada de abundantes SAMs en los arroyos de alta elevación en las montañas de Jemez, en el norte de Nuevo México, EE.UU., queríamos determinar qué combinación de factores físicos están controlando la presencia o ausencia de SAMs en la cuenca del río Jemez. Muestreamos varios sitios en los tres principales sistemas fluviales de la cuenca a lo largo de un gradiente de elevación para determinar los factores físicos, la presencia-ausencia, y el porcentaje de cobertura de cada taxón. Nuestros resultados demostraron que los SAMs se observaron en el 60% de los sitios muestreados que estaban asociados con corrientes más profundas, más estrechas, de menor velocidad y con gradientes bajos. Esta evidencia sugiere que los SAMs en altas elevaciones están afectados por controles abióticos similares a los encontrados para la presencia de SAMs en elevaciones más bajas.","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"150 - 156"},"PeriodicalIF":0.2,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47819999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"VARIATION IN THE DIET OF GREATER ROADRUNNERS (GEOCOCCYX CALIFORNIANUS) IN A MESQUITE-THORNSCRUB ECOSYSTEM","authors":"R. T. Kazmaier, Whitney J. Gann, D. C. Ruthven, David R. Synatzske","doi":"10.1894/0038-4909-66.2.136","DOIUrl":"https://doi.org/10.1894/0038-4909-66.2.136","url":null,"abstract":"Abstract Greater roadrunners (Geococcyx californianus) are conspicuous and well-recognized members of the southwestern fauna. Conventional wisdom suggests that roadrunners prey heavily upon vertebrates, particularly lizards and snakes, but detailed studies are lacking. We investigated roadrunner diet at a site in southern Texas inhabited by four state-threatened reptiles to better characterize seasonal variation in diet and speculate on the relative impact of these predators on state-threatened species. We examined gizzards from 144 greater roadrunners collected across four seasons (Summer 1997, Spring 1998, Summer 1998, Winter 2002) and enumerated the number of food items for each taxa identified. We compared dietary richness, diversity, evenness, number of food items, and similarity among the four seasons. We also evaluated the relationship between roadrunner body size and diet, and we estimated annual consumption rates for each taxa found in the diet. Roadrunner diet was rich and highly variable, but 95.9% of 6,834 identifiable food items were invertebrates. Overall, grasshoppers and beetles dominated all samples. Total number of food items consumed, particularly weevils, birds, and fruit, increased during the winter sampling period. There was a significant, but weakly predictive, inverse relationship between wing chord length and dietary richness. Our calculations suggested the average roadrunner would minimally consume 34,639 prey items per year on this site. Snake consumption was less common than the popular perception of greater roadrunners would suggest. The consumption of vertebrates seemed to coincide with general abundance or when weather patterns decreased abundance of invertebrates. Consumption of two state-threatened species (Texas horned lizard [Phrynosoma cornutum] and Texas indigo snake [Drymarchon melanurus]) occurred, but not at a level to suggest that greater roadrunners negatively impacted populations of these species. Thus, the diet of this species appears to be driven by availability, and greater roadrunners act as exceptional generalist omnivores. Resumen Los correcaminos norteños (Geococcyx californianus) son conspicuos y miembros bien reconocidos de la fauna del suroeste. El conocimiento tradicional sugiere que los correcaminos depredan vertebrados fuertemente, especialmente lagartijas y serpientes, pero se carece de estudios detallados. Investigamos la dieta del correcaminos en un sitio del sur de Texas con presencia de cuatro especies de reptiles catalogados como amenazados a nivel estatal, a fin de caracterizar mejor la variación estacional dietética y evaluar el impacto relativo de estos depredadores sobre estas especies amenazadas. Examinamos las mollejas de 144 correcaminos norteños recolectados durante cuatro estaciones (verano 1997, primavera 1998, verano 1998, invierno 2002) y contabilizamos el número de pedazos de alimento de cada taxón identificado. Comparamos la riqueza de la dieta, su diversidad, uniformidad","PeriodicalId":51157,"journal":{"name":"Southwestern Naturalist","volume":"66 1","pages":"136 - 149"},"PeriodicalIF":0.2,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46486998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}