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Army Ants (army + ant)
Selected AbstractsUse of Premontane Moist Forest and Shade Coffee Agroecosystems by Army Ants in Western PanamaCONSERVATION BIOLOGY, Issue 1 2000Dina L. Roberts Behavioral and distributional studies of these two species have been confined largely to humid lowland forest. We conducted intensive systematic area searches at elevations between 1200 and 1800 m in western Panama to assess the distribution of both species in intact premontane moist forest, shade coffee plantations, and sun coffee plantations. Both species were repeatedly observed in forest, shade coffee plantations close to forest, and shade coffee plantations distant from forest. Neither species was observed in sun coffee plantations. We believe that retention of certain forest-like characteristics in the traditional shade coffee farm contributes to the persistence of these forest organisms in modified landscapes. Large canopy trees not only provide shade that buffers temperature extremes but also supply the ground layer with regular inputs of leaf litter and coarse woody debris from fallen trunks. Both E. burchelli and L. praedator hunt in leaf litter, and E. burchelli uses coarse woody debris as nesting sites ( bivouacs). There were significantly fewer potential bivouacs available in sun coffee plantations than in forest and shade coffee habitats. Also, litter depth was less in sun coffee than in forest and shade coffee. Our results provide the first evidence that shade coffee plantations can provide additional habitat for E. burchelli and L. praedator, top predators of the leaf litter arthropod community. E. burchelli and L. praedator act as critical links between swarm-attendant bird species and leaf-litter arthropods, providing an easily exploited food resource that would otherwise be unavailable for many birds. Continued conversion of shade coffee plantations to sun coffee plantations could have negative effects on army ants and associated biodiversity. Resumen: Las hormigas arrierras Neotropicales, Eciton burchelli y Labidus praedator ( Hymenoptera: Formicidae: Ecitoninae) son especies que requieren de extensas áreas de hábitat para cazar. Los estudios conductuales y de la distribución de estas especies se han realizado principalmente en bosques húmedos en tierras bajas. Desarrollamos búsquedas sistemáticas intensivas en elevaciones entre 1200 y 1800 msnm en Panama occidental para determinar la distribución de ambas especies en bosque húmedo premontano intacto, en plantaciones de café con y sin sombra. Las dos especies fueron observadas recurrentemente en bosque y en plantaciones de café de sombra cercanos y lejanos al bosque. Consideramos que la retención de ciertas características del bosque en las plantaciones de café de sombra contribuye a la persistencia de estos organismos de bosque en ambientes modificados. Los árboles no solo proporcionan sombra que amortigua la temperatura, sino que proporcionan hojarasca y restos leñosos de troncos caídos. Tanto E. burchelli como L. praedator cazan en la hojarasca, E. burchelli utiliza restos leñosos para anidar (vivaques). Encontramos significativamente menos vivaques en plantaciones de café sin sombra al compararlos con bosque y plantaciones de café con sombra. Asimismo, la profundidad de la capa de hojarasca fue menor en plantaciones de café sin sombra en comparación con bosque y plantaciones de café con sombra. Nuestros resultados proporcionan la primera evidencia de que las plantaciones con sombra proporcionan hábitat adicional para E. burchelli y L. praedator, depredadores de la comunidad de artrópodos en la hojarasca. E. burchelli y L. praedator actúan como eslabones críticos entre especies de aves que se alimentan de hormigas y los artrópodos de la hojarasca, proporcionando un recurso alimenticio fácilmente explotado que de otra manera no estaría disponible para muchas aves. La continua transformación de plantaciones de café con sombra a plantaciones sin sombra pudiera tener efectos negativos sobre las hormigas arrieras y la biodiversidad asociada. [source] Army ants in four forests: geographic variation in raid rates and species compositionJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007SEAN O'DONNELL Summary 1The New World army ants are top predators in the litter of tropical forest, but no comprehensive studies exist on variation in assemblage-wide activity and species composition. We used standardized protocols to estimate foraging raid rates and species composition of army ant communities in four Neotropical forests. The study sites spanned approximately 10° latitude, with two sites each in Central and South America. 2We recorded a total of 22 species of army ants. The four sites varied in observed and estimated species richness. Species overlap was highest between the Central American sites, and lowest between the South American sites. 3Raid activity varied significantly among sites. Raid activity per kilometre of trail walks was over four times higher at the most active site (Sta. Maria, Venezuela) than at the least active site (Barro Colorado Island, Panama). Furthermore, each site showed a different diel pattern of activity. For example, raid activity was higher during daylight hours in Costa Rica, and higher at night in Venezuela. Raid activity relationships with ambient temperature also varied significantly among sites. 4The overall rate of army ant raids passing through 1 m2 plots was 0·73 raids per day, but varied among sites, from 0 raids per day (Panama) to 1·2 raids per day (Venezuela). 5Primarily subterranean species were significantly more abundant in Venezuela, and above-ground foragers that form large swarm fronts were least abundant in Panama. The site heterogeneity in species abundance and diel activity patterns has implications for army ant symbionts, including ant-following birds, and for the animals hunted by these top predators. [source] Extreme queen-mating frequency and colony fission in African army antsMOLECULAR ECOLOGY, Issue 8 2004DANIEL J. C. KRONAUER Abstract Army ants have long been suspected to represent an independent origin of multiple queen-mating in the social Hymenoptera. Using microsatellite markers, we show that queens of the African army ant Dorylus (Anomma) molestus have the highest absolute (17.3) and effective (17.5) queen-mating frequencies reported so far for ants. This confirms that obligate multiple queen-mating in social insects is associated with large colony size and advanced social organization, but also raises several novel questions. First, these high estimates place army ants in the range of mating frequencies of honeybees, which have so far been regarded as odd exceptions within the social Hymenoptera. Army ants and honeybees are fundamentally different in morphology and life history, but are the only social insects known that combine obligate multiple mating with reproduction by colony fission and extremely male-biased sex ratios. This implies that the very high numbers of matings in both groups may be due partly to the relatively low costs of additional matings. Second, we were able to trace recent events of colony fission in four of the investigated colonies, where the genotypes of the two queens were only compatible with a mother,daughter relationship. A direct comparison of male production between colonies with offspring from one and two queens, respectively, suggested strongly that new queens do not produce a sexual brood until all workers of the old queen have died, which is consistent with kin selection theory. [source] Use of Premontane Moist Forest and Shade Coffee Agroecosystems by Army Ants in Western PanamaCONSERVATION BIOLOGY, Issue 1 2000Dina L. Roberts Behavioral and distributional studies of these two species have been confined largely to humid lowland forest. We conducted intensive systematic area searches at elevations between 1200 and 1800 m in western Panama to assess the distribution of both species in intact premontane moist forest, shade coffee plantations, and sun coffee plantations. Both species were repeatedly observed in forest, shade coffee plantations close to forest, and shade coffee plantations distant from forest. Neither species was observed in sun coffee plantations. We believe that retention of certain forest-like characteristics in the traditional shade coffee farm contributes to the persistence of these forest organisms in modified landscapes. Large canopy trees not only provide shade that buffers temperature extremes but also supply the ground layer with regular inputs of leaf litter and coarse woody debris from fallen trunks. Both E. burchelli and L. praedator hunt in leaf litter, and E. burchelli uses coarse woody debris as nesting sites ( bivouacs). There were significantly fewer potential bivouacs available in sun coffee plantations than in forest and shade coffee habitats. Also, litter depth was less in sun coffee than in forest and shade coffee. Our results provide the first evidence that shade coffee plantations can provide additional habitat for E. burchelli and L. praedator, top predators of the leaf litter arthropod community. E. burchelli and L. praedator act as critical links between swarm-attendant bird species and leaf-litter arthropods, providing an easily exploited food resource that would otherwise be unavailable for many birds. Continued conversion of shade coffee plantations to sun coffee plantations could have negative effects on army ants and associated biodiversity. Resumen: Las hormigas arrierras Neotropicales, Eciton burchelli y Labidus praedator ( Hymenoptera: Formicidae: Ecitoninae) son especies que requieren de extensas áreas de hábitat para cazar. Los estudios conductuales y de la distribución de estas especies se han realizado principalmente en bosques húmedos en tierras bajas. Desarrollamos búsquedas sistemáticas intensivas en elevaciones entre 1200 y 1800 msnm en Panama occidental para determinar la distribución de ambas especies en bosque húmedo premontano intacto, en plantaciones de café con y sin sombra. Las dos especies fueron observadas recurrentemente en bosque y en plantaciones de café de sombra cercanos y lejanos al bosque. Consideramos que la retención de ciertas características del bosque en las plantaciones de café de sombra contribuye a la persistencia de estos organismos de bosque en ambientes modificados. Los árboles no solo proporcionan sombra que amortigua la temperatura, sino que proporcionan hojarasca y restos leñosos de troncos caídos. Tanto E. burchelli como L. praedator cazan en la hojarasca, E. burchelli utiliza restos leñosos para anidar (vivaques). Encontramos significativamente menos vivaques en plantaciones de café sin sombra al compararlos con bosque y plantaciones de café con sombra. Asimismo, la profundidad de la capa de hojarasca fue menor en plantaciones de café sin sombra en comparación con bosque y plantaciones de café con sombra. Nuestros resultados proporcionan la primera evidencia de que las plantaciones con sombra proporcionan hábitat adicional para E. burchelli y L. praedator, depredadores de la comunidad de artrópodos en la hojarasca. E. burchelli y L. praedator actúan como eslabones críticos entre especies de aves que se alimentan de hormigas y los artrópodos de la hojarasca, proporcionando un recurso alimenticio fácilmente explotado que de otra manera no estaría disponible para muchas aves. La continua transformación de plantaciones de café con sombra a plantaciones sin sombra pudiera tener efectos negativos sobre las hormigas arrieras y la biodiversidad asociada. [source] Elevation and forest clearing effects on foraging differ between surface , and subterranean , foraging army ants (Formicidae: Ecitoninae)JOURNAL OF ANIMAL ECOLOGY, Issue 1 2009Anjali Kumar Summary 1Forest fragmentation often results in a matrix of open areas mixed with patches of forest. Both biotic and abiotic factors can affect consumer species' ability to utilize the altered habitat, especially for species that range over large areas searching for prey. 2Army ants (Formicidae: Ecitoninae) are highly mobile top predators in terrestrial Neotropical ecosystems. Army ant foraging behaviour is influenced by forest clearing at lowland sites, and clearing can reduce army ant population persistence. 3Because high temperatures are implicated in hindering above-ground army ant foraging, we predicted that forest clearing effects on army ant foraging would be reduced at higher (cooler) elevations in montane forest. We also predicted that subterranean foraging, employed by some army ant species, would buffer them from the negative effects of forest clearing. 4We quantified the foraging rates of above-ground and underground foraging army ants at eight sites along an elevational gradient from 1090 to 1540 m a.s.l. We asked whether these two foraging strategies cause a difference in the ability of army ants to forage in open matrix areas relative to elevationally matched forested habitats, and whether elevation predicts open area vs. forest foraging rate differences. 5As predicted, army ants that forage above-ground had lower foraging rates in open areas, but the open area vs. forest difference declined with elevation. In contrast, underground foragers were not affected by habitat type, and underground foraging rates increased with elevation. Ground surface temperatures were higher in open areas than forested areas. Temperatures declined with elevation, and temperature differences between open and forested areas decreased with elevation. 6We conclude that army ants that forage above-ground may be restricted to forested areas due to a thermal tolerance threshold, but that they are released from this limitation at higher elevations. We further suggest that underground foraging permits some army ants to persist within modified landscapes. Our findings have implications for the effects of habitat modification and climate change on these top predators. [source] Army ants in four forests: geographic variation in raid rates and species compositionJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007SEAN O'DONNELL Summary 1The New World army ants are top predators in the litter of tropical forest, but no comprehensive studies exist on variation in assemblage-wide activity and species composition. We used standardized protocols to estimate foraging raid rates and species composition of army ant communities in four Neotropical forests. The study sites spanned approximately 10° latitude, with two sites each in Central and South America. 2We recorded a total of 22 species of army ants. The four sites varied in observed and estimated species richness. Species overlap was highest between the Central American sites, and lowest between the South American sites. 3Raid activity varied significantly among sites. Raid activity per kilometre of trail walks was over four times higher at the most active site (Sta. Maria, Venezuela) than at the least active site (Barro Colorado Island, Panama). Furthermore, each site showed a different diel pattern of activity. For example, raid activity was higher during daylight hours in Costa Rica, and higher at night in Venezuela. Raid activity relationships with ambient temperature also varied significantly among sites. 4The overall rate of army ant raids passing through 1 m2 plots was 0·73 raids per day, but varied among sites, from 0 raids per day (Panama) to 1·2 raids per day (Venezuela). 5Primarily subterranean species were significantly more abundant in Venezuela, and above-ground foragers that form large swarm fronts were least abundant in Panama. The site heterogeneity in species abundance and diel activity patterns has implications for army ant symbionts, including ant-following birds, and for the animals hunted by these top predators. [source] Birds and army ants in a fragment of the Atlantic Forest of BrazilJOURNAL OF FIELD ORNITHOLOGY, Issue 4 2009Christiana M. A. Faria ABSTRACT Little is known about the birds associated with army-ant swarms in the Brazilian Atlantic forest. Our objectives were to locate and monitor army-ant swarms in the Atlantic rainforest of Brazil and to identify the species of birds that attended the swarms and exhibited bivouac-checking behavior. From July 2004 to August 2005, we located 49 swarms of army ants, including 28 Eciton burchelli, 19 Labidus praedator, and 2 Eciton vagans swarms. No birds were present at 17 (35%) swarms. At 32 swarms where birds were present, 22 (69%) were E. burchelli swarms and 10 (31%) were L. praedator swarms. No birds were observed at the two E. vagans swarms. We identified 66 species of birds attending the swarms, but only 43 species were observed foraging on prey flushed by the ants. Eighteen of these species had not been previously reported to forage in association with army-ant swarms. Most birds observed during our study attended army-ant swarms opportunistically, with White-shouldered Fire-eyes (Pyriglena leucoptera) the only obligate ant follower. Our observations suggest that the arthropods and other organisms flushed by army ants represent an important food resource for several species of birds in the Atlantic forest ecosystem. RESUMEN Se conoce poco sobre las aves asociadas con los enjambres de las hormigas soldado en el bosque Atlántico de Brasil. Nuestros objetivos fueron de localizar y monitorear los enjambres de las hormigas soldado en el bosque húmedo del Atlántico en Brasil e identificar las especies de aves que se encontraban junto con los enjambres y que chequeaban a los vivaques de las hormigas. Desde Julio 2004 hasta Agosto 2005, localizamos 49 enjambres de hormigas soldado, incluyendo a 28 enjambres de Eciton burchelli, 19 de Labidus praedator, y dos de Eciton vagans. No detectamos aves en 17 (35%) de los enjambres. En 32 enjambres donde encontramos aves, 22 (69%) eran enjambres de E. burchelli y 10 (31%) eran enjambres de L. praedator. No observamos aves en los dos enjambres de E. vagans. Identificamos 66 especies de aves junto con los enjambres, pero solo 43 especies fueron observadas comiendo las presas ahuyentadas por las hormigas. Dieciocho de estas especies no habían sido anteriormente reportadas forrajeando en conjunto con los enjambres de las hormigas soldado. La mayoría de las aves observadas durante nuestro estudio forrajeaban junto con las hormigas de manera oportunística, con Pyriglena leucoptera siendo la única especie que forrajeaba obligatoriamente con las hormigas soldado. Nuestras observaciones sugieren que los artrópodos y otros organismos que son ahuyentados por las hormigas soldado representan un recurso de comida para una variedad de especies de aves en el ecosistema del bosque Atlántico. [source] Extreme queen-mating frequency and colony fission in African army antsMOLECULAR ECOLOGY, Issue 8 2004DANIEL J. C. KRONAUER Abstract Army ants have long been suspected to represent an independent origin of multiple queen-mating in the social Hymenoptera. Using microsatellite markers, we show that queens of the African army ant Dorylus (Anomma) molestus have the highest absolute (17.3) and effective (17.5) queen-mating frequencies reported so far for ants. This confirms that obligate multiple queen-mating in social insects is associated with large colony size and advanced social organization, but also raises several novel questions. First, these high estimates place army ants in the range of mating frequencies of honeybees, which have so far been regarded as odd exceptions within the social Hymenoptera. Army ants and honeybees are fundamentally different in morphology and life history, but are the only social insects known that combine obligate multiple mating with reproduction by colony fission and extremely male-biased sex ratios. This implies that the very high numbers of matings in both groups may be due partly to the relatively low costs of additional matings. Second, we were able to trace recent events of colony fission in four of the investigated colonies, where the genotypes of the two queens were only compatible with a mother,daughter relationship. A direct comparison of male production between colonies with offspring from one and two queens, respectively, suggested strongly that new queens do not produce a sexual brood until all workers of the old queen have died, which is consistent with kin selection theory. [source] Characterization of 12 new microsatellite loci in Aenictus and Neivamyrmex army antsMOLECULAR ECOLOGY RESOURCES, Issue 4 2007DANIEL J. C. KRONAUER Abstract Here we describe 12 polymorphic microsatellite loci that were cloned and characterized for three species of army ants: the North American Neivamyrmex nigrescens, and the Asian Aenictus laeviceps and Aenictus dentatus. Observed and expected heterozygosities ranged from 0.37 to 0.97 (mean 0.70), and from 0.48 to 0.95 (mean 0.72), respectively. We observed 2,30 (mean 12) alleles per locus. These new genetic markers will be useful for studies of overall population structure and the complex pedigrees in colonies of army ants. [source] Chimpanzees prey on army ants with specialized tool setAMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2010Crickette M. Sanz Abstract Several populations of chimpanzees have been reported to prey upon Dorylus army ants. The most common tool-using technique to gather these ants is with "dipping" probes, which vary in length with regard to aggressiveness and lifestyle of the prey species. We report the use of a tool set in army ant predation by chimpanzees in the Goualougo Triangle, Republic of Congo. We recovered 1,060 tools used in this context and collected 25 video recordings of chimpanzee tool-using behavior at ant nests. Two different types of tools were distinguished based on their form and function. The chimpanzees use a woody sapling to perforate the ant nest, and then a herb stem as a dipping tool to harvest the ants. All of the species of ants preyed upon in Goualougo are present and consumed by chimpanzees at other sites, but there are no other reports of such a regular or widespread use of more than one type of tool to prey upon Dorylus ants. Furthermore, this tool set differs from other types of tool combinations used by chimpanzees at this site for preying upon termites or gathering honey. Therefore, we conclude that these chimpanzees have developed a specialized method for preying upon army ants, which involves the use of an additional tool for opening nests. Further research is needed to determine which specific ecological and social factors may have shaped the emergence and maintenance of this technology. Am. J. Primatol. 72:17,24, 2010. © 2009 Wiley-Liss, Inc. [source] Effects of surface fires on understorey insectivorous birds and terrestrial arthropods in central Brazilian AmazoniaANIMAL CONSERVATION, Issue 4 2003Torbjørn Haugaasen Understorey insectivorous birds are highly vulnerable to different forms of habitat disturbance in tropical forests. Here we examine the effects of an unprecedented surface fire on understorey insectivores and forest litter arthropods in a terra firme forest of central Brazilian Amazonia, and compare species and guild abundance both close to and far from the clearly distinguishable fireline separating burnt and unburnt forest. All six of the most abundant insectivorous foraging guilds examined were detrimentally affected by fire, with dead-leaf gleaners and professional ant-followers being the most heavily affected. While army ants were apparently absent from the burnt forest, results from pit-fall traps showed that wildfires had only a limited effect on the abundance of most leaf-litter invertebrates. The fireline appeared to be an abrupt barrier to many understorey insectivorous birds, and there was little evidence to suggest that primary forest species were recolonizing burnt forest up to 1 year after the fires. Factors affecting the capture frequency of insectivorous birds are discussed. [source] | ||||||||||||||||||||||