Abstract. The Reddish Egret (Egretta rufescens) is considered a species of conservation concern t... more Abstract. The Reddish Egret (Egretta rufescens) is considered a species of conservation concern throughout its range, primarily due to high rates of coastal land loss at key nesting locations. Nest and brood survival, causes and timing of nest failures, as well as nest site characteristics and site selection were studied for three breeding seasons (2016-2018) on a natural marsh island in southwestern Louisiana, USA. Of 110 nesting attempts, 58.2% hatched at least one egg. During incubation, overall daily survival rate was 0.979 (± 0.003 SE), corresponding to 56.4% success from egg laying to hatching. For broods, daily survival rate was 0.993 (± 0.002 SE), or 72.9% success from hatching to fledging. Overwash was identified as the primary cause of known nest and brood loss, accounting for 48.9% and 27.8% of all nest and brood failures, respectively. Overall productivity for breeding pairs within the study area was 1.06 chicks/pair for all years. Data suggests that overwash from extreme high tides and wind can significantly contribute to lower reproductive success of breeding pairs but the lack of mammalian predators on the island may contribute to increased nest success, especially in years that do not experience high water levels.
The Reddish Egret (Egretta rufescens) is a species that is greatly dependent on shallow tidal fla... more The Reddish Egret (Egretta rufescens) is a species that is greatly dependent on shallow tidal flats ideal for its active foraging behavior. It is unknown why some seemingly identical islands are chosen for nesting over others. The goal of this study is to determine if there is a difference in amount of available foraging habitat between mangrove keys in the Lower Florida Keys that do and do not have Reddish Egrets nesting on them within a 5 km, 10 km, and 15 km radius using a geographic information system (GIS). Islands with nesting Reddish Egrets had a greater amount of foraging habitat within a 5 km radius (p = 0.027) while at a radius of 10 km and 15 km there was no difference (p = 0.29, p = 0.32 respectively) between islands containing nesting Reddish Egrets and those without nests. Our results suggest that at short distances of < 5 km, the amount of foraging habitat is important to adult Reddish Egrets choosing an island/nesting location. Protection of foraging habitat in sp...
The maintenance of gene flow in species that have experienced population contractions and are geo... more The maintenance of gene flow in species that have experienced population contractions and are geographically fragmented is important to the maintenance of genetic variation and evolutionary potential; thus, gene flow is also important to conservation and management of these species. For example, the Reddish Egret (Egretta rufescens) has recovered after severe population reductions during the 19th and 20th centuries, but population numbers remain below historic levels. In this study, we characterized gene flow among management units of the Reddish Egret by using ten nuclear microsatellite markers and part of the mitochondrial (mtDNA) control region from 176 nestlings captured at eight localities in Mexico (Baja California, Chiapas, Tamaulipas, and Yucatan), the U.S.A. (Texas, Louisiana, and Florida), and the Bahamas. We found evidence of population structure and that males disperse more often and across longer distances compared to females, which is congruent with previous banding and telemetry data. The maternally inherited mtDNA and biparentally inherited microsatellite data supported slightly different MU models; however, when interpreted together, a four MU model that considered population structure and geographic proximity was most optimal. Namely, MU 1 (Baja California); MU 2 (Chiapas); MU 3 (Yucatan, Tamaulipas, Texas, and Louisiana); and MU 4 (Florida and the Bahamas). Regions outside our sampled localities (e.g., the Greater Antilles and South America) require additional sampling to fully understand gene flow and movement of individuals across the species' entire range. However, the four MUs we have defined group nesting localities into genetically similar subpopulations, which can guide future management plans.
Abstract The endangered Hawaiian petrel (Pterodroma sandwichensis) is endemic to the main Hawaiia... more Abstract The endangered Hawaiian petrel (Pterodroma sandwichensis) is endemic to the main Hawaiian Islands and has undergone a breeding range contraction since the arrival of humans. Using abiotic and biotic environmental variables, we developed a terrestrial habitat suitability model for the species on the island of Kauai based on contemporary sites where the species is known (or strongly suspected) to nest, as well as a habitat/threat-isolation index that combined predictions from this suitability model with spatial information on two anthropogenic threats to the species. After accounting for large-scale relative spatial positioning of sites in modeling procedures, the habitat suitability model suggests that the probability that a location on Kauai could be suitable for Hawaiian petrel nesting activity increases with increasing mean annual wind speed, and may also increase somewhat with increasing slope and native vegetation cover. The habitat suitability model (which does not incorporate spatial information on anthropogenic threats to the species) predicts approximately 74 km2 of Kauai, mostly in the interior of the island, as being potentially suitable with predicted probability > 0.7 for Hawaiian petrel terrestrial activity, and about 35 km2 with predicted probability > 0.9. Encouragingly, almost 50 km2 of land with predicted probability > 0.7 and almost 24 km2 with predicted probability > 0.9 is currently protected, being located on either government or private reserve land. Based on the habitat/threat-isolation index, most land predicted to be both suitable (based on environmental variables) and as isolated from threats as a large number of the known contemporary Hawaiian petrel sites, is found in government and private reserves. Some degree of predicted habitat overlap between the Hawaiian petrel and Newell’s shearwater (Puffinus newelli), another Hawaiian seabird of conservation concern, suggests that some of the same larger tracts of land could potentially be managed jointly for both species, as currently done in Upper Limahuli Preserve and Hono O Na Pali Natural Area Reserve on Kauai.
In the present study the analysis of the physico-chemical parameters of the collected TWW shows t... more In the present study the analysis of the physico-chemical parameters of the collected TWW shows the BOD, COD, COT, Cl-, NO 3 , NO 2 , suspended matter, organic matter, turbidity and conductivity were in accordance with the required Tunisian legislations. In the same occurrence, the ICP-MS and the UPLC-MS/MS analysis show that TWW were devoid of different toxic metals and antibiotics, respectively. We opted to reuse of the TWW in the irrigation of young olive trees of two varieties: Olea europaea L. cv. Chetoui and Olea europaea L. cv. Chemlali which receiving 1L/week of TWW during five months. Results show that dry roots weight and the content of chlorophyll a in 'Chetoui' variety increased significantly (p<0.05) when compared to the control group. On the same way, significantly increase of leaf area, dry roots and leaves weights was observed in 'Chemlali' variety treated with TWW.
The popularity of using unmanned aerial vehicles (UAVs) to survey colonial waterbirds has increas... more The popularity of using unmanned aerial vehicles (UAVs) to survey colonial waterbirds has increased in the past decade, but disturbance associated with this bourgeoning technology requires further study. Disturbance was investigated by conducting aerial surveys with a consumer-grade quadcopter (DJI Phantom 3), while concurrently recording behavioural reactions on video. Surveys of mixed-species waterbird colonies (1-6 species per colony) were flown in horizontal transects at heights of 122, 91, 61, and 46 m, which is a typical range for collecting aerial imagery and producing high-resolution mosaicked orthophotos of nesting bird sites. An upper limit of 122 m was used due to local regulations prohibiting higher-altitude flights without federal authorization. Behavioural reactions were tallied every minute and a disturbance score was calculated for each sampling period. When compared to control periods, we found no evidence that colony-wide escape (i.e., flight) behaviour increased d...
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Abstract. At the 40th Annual Conference and General Meeting of the Waterbird Society, a symposium... more Abstract. At the 40th Annual Conference and General Meeting of the Waterbird Society, a symposium and workshop titled Herons of the World Symposium was convened to address the current world status of Ardeidae (herons). This paper introduces the origin of this symposium, demonstrates the geographical areas of study and proposes a framework for future world symposia on coastal and freshwater colonial waterbirds. In that way, it complements the coverage of pelagic colonial waterbirds by the World Seabird Union. The Herons of the World Symposium was held in New Bern, North Carolina, USA, during 21–23 September 2016. The purpose of this first symposium was to bring together heron researchers and enthusiasts from around the world to meet and discuss local, regional and international advances in their biology. In this Special Section, four papers from the symposium are presented. Additional papers and research summaries of participants can be found in the online Journal of Heron Biology and Conservation.
Abstract The ability of songbirds to survive and reproduce depends on many factors, one of which ... more Abstract The ability of songbirds to survive and reproduce depends on many factors, one of which is the ability to acquire enough food. We quantified foraging behavior, nestinghabitat vegetation composition, and available arthropod prey of the Vireo atricapilla (Black-capped Vireo) in Texas during 2010 and 2011. We used observational surveys of foraging behavior and vegetation time-use to quantify the Black-capped Vireos' foraging behavior and vegetative use versus availability (i.e., mean proportion of use vs. vegetative species availability). We collected descriptive data on the Black-capped Vireos' foraging use of available vegetative species and compared among vegetative species, year, and within-season sampling periods. In 2010 and 2011, we identified and mapped 49 and 63 breeding territories and repeatedly surveyed 30 and 58 territories for foraging activity, respectively. Data analysis focused on the foraging use of the 3 most commonly used and available tree species: Juniperus ashei (Ashe Juniper), Quercus sinuata (Shin Oak), and Q. fusiformis (Live Oak). Ashe Juniper, Shin Oak, and Live Oak together made up 78.8% and 83.6% of total proportion of substrate for foraging efforts in 2010 and 2011, respectively. Ashe Juniper had the highest proportion (~28–50%) of foraging effort in 2010, 2011, and all but 1 sampling period for both years. We also repeatedly collected branch clippings from within a random subset of surveyed Black-capped Vireo territories to identify potentially available arthropod foods. We evaluated by order richness, total abundance, and dry biomass to make comparisons among vegetative species, year, and within-season sampling periods. We found significant differences in the biomass of arthropod orders Acari and Thysanoptera in 2010 and between orders Acari and Hymenoptera in 2011 among the 3 focal vegetative species. Examination of additional descriptive data suggests seasonal changes in potentially available arthropod foods. Our research underscores the importance of vegetation composition to Black-capped Vireos that may help habitat managers select for potential vegetative species distributions to optimize food resources throughout the breeding season for this species.
Brock Geary 1, M. Clay Green 1, Daniel Reed 2, Bart M. Ballard 2 and Bill Howe 3,(1) Department o... more Brock Geary 1, M. Clay Green 1, Daniel Reed 2, Bart M. Ballard 2 and Bill Howe 3,(1) Department of Population and Conservation Biology, Texas State University-San Marcos, San Marcos, TX,(2) Texas A&M University-Kingsville,(3) US Fish & Wildlife Service, ...
ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adja... more ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adjacent terrestrial habitats through the exchange of organic matter, nutrients, and organisms. Traditionally, it was thought that the dominant directionality of the movement of inorganic and organic matter (OM) was from terrestrial to stream habitats; however, there has been a recent focus on the importance of aquatic-derived resources for adjacent riparian terrestrial habitats. The reliance on aquatic-derived resources may be particularly relevant in arid landscapes because perennially-flowing rivers and streams can have relatively high in situ productivity which will lead to OM “spill out” to the surrounding terrestrial landscape, providing an allochthonously-derived resource subsidy to riparian consumers (i.e. insectivorous bats, birds, lizards, and spiders) in the form of emerging insects. Ecotoxicologists and environmental scientists have recently expanded the concept of cross-ecosystem resource subsidies to include the transfer of bioaccumulating contaminants. Mercury (Hg) is a toxic element with no known biological function found in a variety of environments around the world. Through our activities, humans have greatly altered the global Hg cycle and subsequently released large amounts of Hg to the environment. The input of Hg into aquatic systems occurs largely through atmospheric deposition of inorganic Hg, but the movement of aquatically-derived Hg to terrestrial environments is likely biologically mediated via the movement of organisms crossing ecosystems boundaries (e.g., movement of organisms from aquatic to terrestrial environments). In this study, we assessed the importance of Hg transport from lotic ecosystems via aquatic insect emergences to terrestrial consumers. We examined the Hg concentration in in-stream food web components (fishes and aquatic invertebrates) and in terrestrial consumers which forage in riparian zones, such as bats, birds and spiders. The study sites included two “High Hg” stream ecosystems which have known geological Hg and a past history of Hg mining in the watersheds, and one “Low Hg” stream with little geological Hg and no Hg mining in its watershed. Results/Conclusions Fishes and aquatic invertebrates at the “High Hg” sites generally exhibited higher Hg concentrations than at the “Low Hg” site. We found significantly higher Hg concentrations in feathers of both resident and migrant birds at the “High Hg” sites. However, we did not detect significant differences in Hg concentrations in insectivorous bats and terrestrial invertebrates among the “High” and “Low” sites. This study supports a growing body of evidence demonstrating the role that aquatic organisms play in movement of toxicants to terrestrial ecosystems.
Distinguishing the sexes of adult American Oystercatchers in the field is challenging because thi... more Distinguishing the sexes of adult American Oystercatchers in the field is challenging because this species is plumage monomorphic and there is considerable overlap between the sexes in morphometric measurements. We attempted to shed light on this challenge by examining a trait that American Oystercatchers share with other oystercatcher species; the presence of iridial depigmentation, or darkened regions within the yellow iris, known as eye flecks. We used morphometric measurements coupled with the presence and severity of eye flecks to sex pairs of adult oystercatchers, captured as part of a larger study addressing the species’ breeding ecology in Texas. We collected whole blood for genetic determination of sex using polymerase chain reaction (PCR) amplification of the chromo-helicase-DNA binding protein (CHD) gene on avian sex chromosomes Z and W to confirm the reliability of morphometrics and amount of eye flecks as diagnostic tools in our assignment of sex. We captured and sexed ...
The global distribution of the reddish egret is characterized by disjunct colonies occurring from... more The global distribution of the reddish egret is characterized by disjunct colonies occurring from the Pacific side of Northwest Mexico to the Caribbean. We examined distantly isolated colonies of reddish egret to determine global population genetic structure. We used seven polymorphic microsatellites to accomplish five goals: (1) to assess range wide population differentiation among reddish egret (Egretta rufescens) populations, (2) identify extent of gene flow, (3) determine any historical occurrence of bottlenecks, (4) assess genetic differentiation between color morphs, (5) clarify subspecies status of E.r. dickeyi, a completely dark morph population located in and around the Baja California peninsula, Mexico. Genetic differentiation was dramatic (global Fst = 0.161) throughout the reddish egrets range extending from Baja California, Mexico to Great Inagua, Bahamas. Differentiation occurred among three distinct regions (Fst = 0.238) but not among colonies/islands within regions suggesting regional philopatry. Genetic diversity (alleles per locus, and heterozygosity) in Baja California Sur, Mexico and Great Inagua, Bahamas populations is lower than in the Texas/Mexico population due to minimal dispersal between regions and smaller population sizes. Dark and white color morphs when present within the same region showed no differentiation. Patterns of recent population bottlenecks are not evident in each of the three regional populations. With evidence of limited gene flow in addition to low genetic diversity and prospects of habitat loss we recommend that reddish egrets be managed as three distinct or evolutionary significant units.
ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adja... more ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adjacent terrestrial habitats through the exchange of organic matter, nutrients, and organisms. Traditionally, it was thought that the dominant directionality of the movement of inorganic and organic matter (OM) was from terrestrial to stream habitats; however, there has been a recent focus on the importance of aquatic-derived resources for adjacent riparian terrestrial habitats. The reliance on aquatic-derived resources may be particularly relevant in arid landscapes because perennially-flowing rivers and streams can have relatively high in situ productivity which will lead to OM “spill out” to the surrounding terrestrial landscape, providing an allochthonously-derived resource subsidy to riparian consumers (i.e. insectivorous bats, birds, lizards, and spiders) in the form of emerging insects. Ecotoxicologists and environmental scientists have recently expanded the concept of cross-ecosystem resource subsidies to include the transfer of bioaccumulating contaminants. Mercury (Hg) is a toxic element with no known biological function found in a variety of environments around the world. Through our activities, humans have greatly altered the global Hg cycle and subsequently released large amounts of Hg to the environment. The input of Hg into aquatic systems occurs largely through atmospheric deposition of inorganic Hg, but the movement of aquatically-derived Hg to terrestrial environments is likely biologically mediated via the movement of organisms crossing ecosystems boundaries (e.g., movement of organisms from aquatic to terrestrial environments). In this study, we assessed the importance of Hg transport from lotic ecosystems via aquatic insect emergences to terrestrial consumers. We examined the Hg concentration in in-stream food web components (fishes and aquatic invertebrates) and in terrestrial consumers which forage in riparian zones, such as bats, birds and spiders. The study sites included two “High Hg” stream ecosystems which have known geological Hg and a past history of Hg mining in the watersheds, and one “Low Hg” stream with little geological Hg and no Hg mining in its watershed. Results/Conclusions Fishes and aquatic invertebrates at the “High Hg” sites generally exhibited higher Hg concentrations than at the “Low Hg” site. We found significantly higher Hg concentrations in feathers of both resident and migrant birds at the “High Hg” sites. However, we did not detect significant differences in Hg concentrations in insectivorous bats and terrestrial invertebrates among the “High” and “Low” sites. This study supports a growing body of evidence demonstrating the role that aquatic organisms play in movement of toxicants to terrestrial ecosystems.
Abstract. The Reddish Egret (Egretta rufescens) is considered a species of conservation concern t... more Abstract. The Reddish Egret (Egretta rufescens) is considered a species of conservation concern throughout its range, primarily due to high rates of coastal land loss at key nesting locations. Nest and brood survival, causes and timing of nest failures, as well as nest site characteristics and site selection were studied for three breeding seasons (2016-2018) on a natural marsh island in southwestern Louisiana, USA. Of 110 nesting attempts, 58.2% hatched at least one egg. During incubation, overall daily survival rate was 0.979 (± 0.003 SE), corresponding to 56.4% success from egg laying to hatching. For broods, daily survival rate was 0.993 (± 0.002 SE), or 72.9% success from hatching to fledging. Overwash was identified as the primary cause of known nest and brood loss, accounting for 48.9% and 27.8% of all nest and brood failures, respectively. Overall productivity for breeding pairs within the study area was 1.06 chicks/pair for all years. Data suggests that overwash from extreme high tides and wind can significantly contribute to lower reproductive success of breeding pairs but the lack of mammalian predators on the island may contribute to increased nest success, especially in years that do not experience high water levels.
The Reddish Egret (Egretta rufescens) is a species that is greatly dependent on shallow tidal fla... more The Reddish Egret (Egretta rufescens) is a species that is greatly dependent on shallow tidal flats ideal for its active foraging behavior. It is unknown why some seemingly identical islands are chosen for nesting over others. The goal of this study is to determine if there is a difference in amount of available foraging habitat between mangrove keys in the Lower Florida Keys that do and do not have Reddish Egrets nesting on them within a 5 km, 10 km, and 15 km radius using a geographic information system (GIS). Islands with nesting Reddish Egrets had a greater amount of foraging habitat within a 5 km radius (p = 0.027) while at a radius of 10 km and 15 km there was no difference (p = 0.29, p = 0.32 respectively) between islands containing nesting Reddish Egrets and those without nests. Our results suggest that at short distances of < 5 km, the amount of foraging habitat is important to adult Reddish Egrets choosing an island/nesting location. Protection of foraging habitat in sp...
The maintenance of gene flow in species that have experienced population contractions and are geo... more The maintenance of gene flow in species that have experienced population contractions and are geographically fragmented is important to the maintenance of genetic variation and evolutionary potential; thus, gene flow is also important to conservation and management of these species. For example, the Reddish Egret (Egretta rufescens) has recovered after severe population reductions during the 19th and 20th centuries, but population numbers remain below historic levels. In this study, we characterized gene flow among management units of the Reddish Egret by using ten nuclear microsatellite markers and part of the mitochondrial (mtDNA) control region from 176 nestlings captured at eight localities in Mexico (Baja California, Chiapas, Tamaulipas, and Yucatan), the U.S.A. (Texas, Louisiana, and Florida), and the Bahamas. We found evidence of population structure and that males disperse more often and across longer distances compared to females, which is congruent with previous banding and telemetry data. The maternally inherited mtDNA and biparentally inherited microsatellite data supported slightly different MU models; however, when interpreted together, a four MU model that considered population structure and geographic proximity was most optimal. Namely, MU 1 (Baja California); MU 2 (Chiapas); MU 3 (Yucatan, Tamaulipas, Texas, and Louisiana); and MU 4 (Florida and the Bahamas). Regions outside our sampled localities (e.g., the Greater Antilles and South America) require additional sampling to fully understand gene flow and movement of individuals across the species' entire range. However, the four MUs we have defined group nesting localities into genetically similar subpopulations, which can guide future management plans.
Abstract The endangered Hawaiian petrel (Pterodroma sandwichensis) is endemic to the main Hawaiia... more Abstract The endangered Hawaiian petrel (Pterodroma sandwichensis) is endemic to the main Hawaiian Islands and has undergone a breeding range contraction since the arrival of humans. Using abiotic and biotic environmental variables, we developed a terrestrial habitat suitability model for the species on the island of Kauai based on contemporary sites where the species is known (or strongly suspected) to nest, as well as a habitat/threat-isolation index that combined predictions from this suitability model with spatial information on two anthropogenic threats to the species. After accounting for large-scale relative spatial positioning of sites in modeling procedures, the habitat suitability model suggests that the probability that a location on Kauai could be suitable for Hawaiian petrel nesting activity increases with increasing mean annual wind speed, and may also increase somewhat with increasing slope and native vegetation cover. The habitat suitability model (which does not incorporate spatial information on anthropogenic threats to the species) predicts approximately 74 km2 of Kauai, mostly in the interior of the island, as being potentially suitable with predicted probability > 0.7 for Hawaiian petrel terrestrial activity, and about 35 km2 with predicted probability > 0.9. Encouragingly, almost 50 km2 of land with predicted probability > 0.7 and almost 24 km2 with predicted probability > 0.9 is currently protected, being located on either government or private reserve land. Based on the habitat/threat-isolation index, most land predicted to be both suitable (based on environmental variables) and as isolated from threats as a large number of the known contemporary Hawaiian petrel sites, is found in government and private reserves. Some degree of predicted habitat overlap between the Hawaiian petrel and Newell’s shearwater (Puffinus newelli), another Hawaiian seabird of conservation concern, suggests that some of the same larger tracts of land could potentially be managed jointly for both species, as currently done in Upper Limahuli Preserve and Hono O Na Pali Natural Area Reserve on Kauai.
In the present study the analysis of the physico-chemical parameters of the collected TWW shows t... more In the present study the analysis of the physico-chemical parameters of the collected TWW shows the BOD, COD, COT, Cl-, NO 3 , NO 2 , suspended matter, organic matter, turbidity and conductivity were in accordance with the required Tunisian legislations. In the same occurrence, the ICP-MS and the UPLC-MS/MS analysis show that TWW were devoid of different toxic metals and antibiotics, respectively. We opted to reuse of the TWW in the irrigation of young olive trees of two varieties: Olea europaea L. cv. Chetoui and Olea europaea L. cv. Chemlali which receiving 1L/week of TWW during five months. Results show that dry roots weight and the content of chlorophyll a in 'Chetoui' variety increased significantly (p<0.05) when compared to the control group. On the same way, significantly increase of leaf area, dry roots and leaves weights was observed in 'Chemlali' variety treated with TWW.
The popularity of using unmanned aerial vehicles (UAVs) to survey colonial waterbirds has increas... more The popularity of using unmanned aerial vehicles (UAVs) to survey colonial waterbirds has increased in the past decade, but disturbance associated with this bourgeoning technology requires further study. Disturbance was investigated by conducting aerial surveys with a consumer-grade quadcopter (DJI Phantom 3), while concurrently recording behavioural reactions on video. Surveys of mixed-species waterbird colonies (1-6 species per colony) were flown in horizontal transects at heights of 122, 91, 61, and 46 m, which is a typical range for collecting aerial imagery and producing high-resolution mosaicked orthophotos of nesting bird sites. An upper limit of 122 m was used due to local regulations prohibiting higher-altitude flights without federal authorization. Behavioural reactions were tallied every minute and a disturbance score was calculated for each sampling period. When compared to control periods, we found no evidence that colony-wide escape (i.e., flight) behaviour increased d...
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Abstract. At the 40th Annual Conference and General Meeting of the Waterbird Society, a symposium... more Abstract. At the 40th Annual Conference and General Meeting of the Waterbird Society, a symposium and workshop titled Herons of the World Symposium was convened to address the current world status of Ardeidae (herons). This paper introduces the origin of this symposium, demonstrates the geographical areas of study and proposes a framework for future world symposia on coastal and freshwater colonial waterbirds. In that way, it complements the coverage of pelagic colonial waterbirds by the World Seabird Union. The Herons of the World Symposium was held in New Bern, North Carolina, USA, during 21–23 September 2016. The purpose of this first symposium was to bring together heron researchers and enthusiasts from around the world to meet and discuss local, regional and international advances in their biology. In this Special Section, four papers from the symposium are presented. Additional papers and research summaries of participants can be found in the online Journal of Heron Biology and Conservation.
Abstract The ability of songbirds to survive and reproduce depends on many factors, one of which ... more Abstract The ability of songbirds to survive and reproduce depends on many factors, one of which is the ability to acquire enough food. We quantified foraging behavior, nestinghabitat vegetation composition, and available arthropod prey of the Vireo atricapilla (Black-capped Vireo) in Texas during 2010 and 2011. We used observational surveys of foraging behavior and vegetation time-use to quantify the Black-capped Vireos' foraging behavior and vegetative use versus availability (i.e., mean proportion of use vs. vegetative species availability). We collected descriptive data on the Black-capped Vireos' foraging use of available vegetative species and compared among vegetative species, year, and within-season sampling periods. In 2010 and 2011, we identified and mapped 49 and 63 breeding territories and repeatedly surveyed 30 and 58 territories for foraging activity, respectively. Data analysis focused on the foraging use of the 3 most commonly used and available tree species: Juniperus ashei (Ashe Juniper), Quercus sinuata (Shin Oak), and Q. fusiformis (Live Oak). Ashe Juniper, Shin Oak, and Live Oak together made up 78.8% and 83.6% of total proportion of substrate for foraging efforts in 2010 and 2011, respectively. Ashe Juniper had the highest proportion (~28–50%) of foraging effort in 2010, 2011, and all but 1 sampling period for both years. We also repeatedly collected branch clippings from within a random subset of surveyed Black-capped Vireo territories to identify potentially available arthropod foods. We evaluated by order richness, total abundance, and dry biomass to make comparisons among vegetative species, year, and within-season sampling periods. We found significant differences in the biomass of arthropod orders Acari and Thysanoptera in 2010 and between orders Acari and Hymenoptera in 2011 among the 3 focal vegetative species. Examination of additional descriptive data suggests seasonal changes in potentially available arthropod foods. Our research underscores the importance of vegetation composition to Black-capped Vireos that may help habitat managers select for potential vegetative species distributions to optimize food resources throughout the breeding season for this species.
Brock Geary 1, M. Clay Green 1, Daniel Reed 2, Bart M. Ballard 2 and Bill Howe 3,(1) Department o... more Brock Geary 1, M. Clay Green 1, Daniel Reed 2, Bart M. Ballard 2 and Bill Howe 3,(1) Department of Population and Conservation Biology, Texas State University-San Marcos, San Marcos, TX,(2) Texas A&M University-Kingsville,(3) US Fish & Wildlife Service, ...
ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adja... more ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adjacent terrestrial habitats through the exchange of organic matter, nutrients, and organisms. Traditionally, it was thought that the dominant directionality of the movement of inorganic and organic matter (OM) was from terrestrial to stream habitats; however, there has been a recent focus on the importance of aquatic-derived resources for adjacent riparian terrestrial habitats. The reliance on aquatic-derived resources may be particularly relevant in arid landscapes because perennially-flowing rivers and streams can have relatively high in situ productivity which will lead to OM “spill out” to the surrounding terrestrial landscape, providing an allochthonously-derived resource subsidy to riparian consumers (i.e. insectivorous bats, birds, lizards, and spiders) in the form of emerging insects. Ecotoxicologists and environmental scientists have recently expanded the concept of cross-ecosystem resource subsidies to include the transfer of bioaccumulating contaminants. Mercury (Hg) is a toxic element with no known biological function found in a variety of environments around the world. Through our activities, humans have greatly altered the global Hg cycle and subsequently released large amounts of Hg to the environment. The input of Hg into aquatic systems occurs largely through atmospheric deposition of inorganic Hg, but the movement of aquatically-derived Hg to terrestrial environments is likely biologically mediated via the movement of organisms crossing ecosystems boundaries (e.g., movement of organisms from aquatic to terrestrial environments). In this study, we assessed the importance of Hg transport from lotic ecosystems via aquatic insect emergences to terrestrial consumers. We examined the Hg concentration in in-stream food web components (fishes and aquatic invertebrates) and in terrestrial consumers which forage in riparian zones, such as bats, birds and spiders. The study sites included two “High Hg” stream ecosystems which have known geological Hg and a past history of Hg mining in the watersheds, and one “Low Hg” stream with little geological Hg and no Hg mining in its watershed. Results/Conclusions Fishes and aquatic invertebrates at the “High Hg” sites generally exhibited higher Hg concentrations than at the “Low Hg” site. We found significantly higher Hg concentrations in feathers of both resident and migrant birds at the “High Hg” sites. However, we did not detect significant differences in Hg concentrations in insectivorous bats and terrestrial invertebrates among the “High” and “Low” sites. This study supports a growing body of evidence demonstrating the role that aquatic organisms play in movement of toxicants to terrestrial ecosystems.
Distinguishing the sexes of adult American Oystercatchers in the field is challenging because thi... more Distinguishing the sexes of adult American Oystercatchers in the field is challenging because this species is plumage monomorphic and there is considerable overlap between the sexes in morphometric measurements. We attempted to shed light on this challenge by examining a trait that American Oystercatchers share with other oystercatcher species; the presence of iridial depigmentation, or darkened regions within the yellow iris, known as eye flecks. We used morphometric measurements coupled with the presence and severity of eye flecks to sex pairs of adult oystercatchers, captured as part of a larger study addressing the species’ breeding ecology in Texas. We collected whole blood for genetic determination of sex using polymerase chain reaction (PCR) amplification of the chromo-helicase-DNA binding protein (CHD) gene on avian sex chromosomes Z and W to confirm the reliability of morphometrics and amount of eye flecks as diagnostic tools in our assignment of sex. We captured and sexed ...
The global distribution of the reddish egret is characterized by disjunct colonies occurring from... more The global distribution of the reddish egret is characterized by disjunct colonies occurring from the Pacific side of Northwest Mexico to the Caribbean. We examined distantly isolated colonies of reddish egret to determine global population genetic structure. We used seven polymorphic microsatellites to accomplish five goals: (1) to assess range wide population differentiation among reddish egret (Egretta rufescens) populations, (2) identify extent of gene flow, (3) determine any historical occurrence of bottlenecks, (4) assess genetic differentiation between color morphs, (5) clarify subspecies status of E.r. dickeyi, a completely dark morph population located in and around the Baja California peninsula, Mexico. Genetic differentiation was dramatic (global Fst = 0.161) throughout the reddish egrets range extending from Baja California, Mexico to Great Inagua, Bahamas. Differentiation occurred among three distinct regions (Fst = 0.238) but not among colonies/islands within regions suggesting regional philopatry. Genetic diversity (alleles per locus, and heterozygosity) in Baja California Sur, Mexico and Great Inagua, Bahamas populations is lower than in the Texas/Mexico population due to minimal dispersal between regions and smaller population sizes. Dark and white color morphs when present within the same region showed no differentiation. Patterns of recent population bottlenecks are not evident in each of the three regional populations. With evidence of limited gene flow in addition to low genetic diversity and prospects of habitat loss we recommend that reddish egrets be managed as three distinct or evolutionary significant units.
ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adja... more ABSTRACT Background/Question/Methods Stream and river ecosystems are intimately connected to adjacent terrestrial habitats through the exchange of organic matter, nutrients, and organisms. Traditionally, it was thought that the dominant directionality of the movement of inorganic and organic matter (OM) was from terrestrial to stream habitats; however, there has been a recent focus on the importance of aquatic-derived resources for adjacent riparian terrestrial habitats. The reliance on aquatic-derived resources may be particularly relevant in arid landscapes because perennially-flowing rivers and streams can have relatively high in situ productivity which will lead to OM “spill out” to the surrounding terrestrial landscape, providing an allochthonously-derived resource subsidy to riparian consumers (i.e. insectivorous bats, birds, lizards, and spiders) in the form of emerging insects. Ecotoxicologists and environmental scientists have recently expanded the concept of cross-ecosystem resource subsidies to include the transfer of bioaccumulating contaminants. Mercury (Hg) is a toxic element with no known biological function found in a variety of environments around the world. Through our activities, humans have greatly altered the global Hg cycle and subsequently released large amounts of Hg to the environment. The input of Hg into aquatic systems occurs largely through atmospheric deposition of inorganic Hg, but the movement of aquatically-derived Hg to terrestrial environments is likely biologically mediated via the movement of organisms crossing ecosystems boundaries (e.g., movement of organisms from aquatic to terrestrial environments). In this study, we assessed the importance of Hg transport from lotic ecosystems via aquatic insect emergences to terrestrial consumers. We examined the Hg concentration in in-stream food web components (fishes and aquatic invertebrates) and in terrestrial consumers which forage in riparian zones, such as bats, birds and spiders. The study sites included two “High Hg” stream ecosystems which have known geological Hg and a past history of Hg mining in the watersheds, and one “Low Hg” stream with little geological Hg and no Hg mining in its watershed. Results/Conclusions Fishes and aquatic invertebrates at the “High Hg” sites generally exhibited higher Hg concentrations than at the “Low Hg” site. We found significantly higher Hg concentrations in feathers of both resident and migrant birds at the “High Hg” sites. However, we did not detect significant differences in Hg concentrations in insectivorous bats and terrestrial invertebrates among the “High” and “Low” sites. This study supports a growing body of evidence demonstrating the role that aquatic organisms play in movement of toxicants to terrestrial ecosystems.
Uploads
Papers by Clay Green