-Choice of daily flight routes by Greater White-fronted Geese (Anser albifrons) were related to the position of power lines over rice fields and in woodland adjacent to Lake Izunuma-Uchinuma, northernJapan, during October-February in 1996-97, 1997-98 and 1998-99. Two types of route were considered: flight lines over power lines standing in the rice fields and flight lines over power lines partially concealed in woodland. Although food availability (size of rice fields within 12 km of the lake beyond the rice fields) was similar for direct flight lines beyond the two positions of the power lines, the proportion of geese flying over the power lines standing in the woods was appreciably and significantly higher than those in rice fields. In some cases, the geese took an indirect flight route to avoid crossing the power lines in the rice fields. It is evident that the position and "exposure" of power lines affect the flight behavior of geese. Received 30 May 2001, accepted 8 August 2001.
{"title":"Choice of Daily Flight Routes of Greater White-Fronted Geese: Effects of Power Lines","authors":"T. Shimada","doi":"10.2307/1522075","DOIUrl":"https://doi.org/10.2307/1522075","url":null,"abstract":"-Choice of daily flight routes by Greater White-fronted Geese (Anser albifrons) were related to the position of power lines over rice fields and in woodland adjacent to Lake Izunuma-Uchinuma, northernJapan, during October-February in 1996-97, 1997-98 and 1998-99. Two types of route were considered: flight lines over power lines standing in the rice fields and flight lines over power lines partially concealed in woodland. Although food availability (size of rice fields within 12 km of the lake beyond the rice fields) was similar for direct flight lines beyond the two positions of the power lines, the proportion of geese flying over the power lines standing in the woods was appreciably and significantly higher than those in rice fields. In some cases, the geese took an indirect flight route to avoid crossing the power lines in the rice fields. It is evident that the position and \"exposure\" of power lines affect the flight behavior of geese. Received 30 May 2001, accepted 8 August 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"34 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121334668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
-Adult Purple Herons (Ardea purpurea) were observed while foraging along rivers and rice fields during the breeding season. Proportion of foraging time was higher in rice fields than on rivers and the relationship between biomass ingested in relation to foraging time was greater on rivers. The success of feeding attempts was similar in both habitats. Most Purple Herons preferred to forage along rivers but rice fields may be a valuable option. Received 12 May 2001, accepted 8July 2001.
{"title":"Are Rice Fields a Suitable Foraging Habitat for Purple Herons during the Breeding Season","authors":"F. Campos, J. M. Lekuona","doi":"10.2307/1522081","DOIUrl":"https://doi.org/10.2307/1522081","url":null,"abstract":"-Adult Purple Herons (Ardea purpurea) were observed while foraging along rivers and rice fields during the breeding season. Proportion of foraging time was higher in rice fields than on rivers and the relationship between biomass ingested in relation to foraging time was greater on rivers. The success of feeding attempts was similar in both habitats. Most Purple Herons preferred to forage along rivers but rice fields may be a valuable option. Received 12 May 2001, accepted 8July 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114218959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Tourenq, C. Pin, L. Sacchi, S. Hurtrez-Boussès, Guillaume Bertault, Y. Kayser, Jean-Louis Martin
-High nest densities in colonial birds is assumed to favor the infection of individuals by parasites. Little Egrets (Egretta garzetta) chicks (N = 187) were sampled before nest departure in six different colonies of the Camargue, southern France, to determine the prevalence of Haematozoa infection. The absence of blood parasites is discussed. Received 8 August 2001, accepted 25 August 2001.
{"title":"Absence of Haematozoa in Chicks of Little Egret in the Camargue, Southern France","authors":"C. Tourenq, C. Pin, L. Sacchi, S. Hurtrez-Boussès, Guillaume Bertault, Y. Kayser, Jean-Louis Martin","doi":"10.2307/1522077","DOIUrl":"https://doi.org/10.2307/1522077","url":null,"abstract":"-High nest densities in colonial birds is assumed to favor the infection of individuals by parasites. Little Egrets (Egretta garzetta) chicks (N = 187) were sampled before nest departure in six different colonies of the Camargue, southern France, to determine the prevalence of Haematozoa infection. The absence of blood parasites is discussed. Received 8 August 2001, accepted 25 August 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123867112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
-Molting is a fundamental biological process common to all birds, and understanding molt strategies is an integral part of studying any species' life history. Molt of the monotypic Ivory Gull (Pagophila eburnea) has received variable and often contradictory treatment in the literature. Based upon examination of 152 museum specimens, the unique molt strategy of this species is clarified. Juveniles molt directly into definitive (= adult) basic plumage via a complete molt during April to August of their second calendar year. Adults have only a single molt per cycle, a strategy unique among gulls: their prebasic molt starts in March and April, progresses quickly, and is mostly completed before the pre-laying to hatching period (mid June to early August); adults typically suspend primary molt at this time and conclude molt of outermost primaries in late August or September. Thus molt and breeding overlap broadly in the Ivory Gull, presumably an adaptation to the constraints of its high-latitude winter range and the brief Arctic summer. Received iJuly 2001, accepted 12 August 2001.
{"title":"Molt of the Ivory Gull","authors":"S. Howell","doi":"10.2307/1522078","DOIUrl":"https://doi.org/10.2307/1522078","url":null,"abstract":"-Molting is a fundamental biological process common to all birds, and understanding molt strategies is an integral part of studying any species' life history. Molt of the monotypic Ivory Gull (Pagophila eburnea) has received variable and often contradictory treatment in the literature. Based upon examination of 152 museum specimens, the unique molt strategy of this species is clarified. Juveniles molt directly into definitive (= adult) basic plumage via a complete molt during April to August of their second calendar year. Adults have only a single molt per cycle, a strategy unique among gulls: their prebasic molt starts in March and April, progresses quickly, and is mostly completed before the pre-laying to hatching period (mid June to early August); adults typically suspend primary molt at this time and conclude molt of outermost primaries in late August or September. Thus molt and breeding overlap broadly in the Ivory Gull, presumably an adaptation to the constraints of its high-latitude winter range and the brief Arctic summer. Received iJuly 2001, accepted 12 August 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114997939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
-We investigated wading bird productivity in four estuaries from Delaware Bay to Boston Harbor in northeastern U.S.A. over the period 1986-1998. To document and characterize reproductive performance of numerically dominant species for use in wildlife and habitat management planning, we recorded 1) number of eggs laid, 2) percent of eggs hatched, 3) percent of hatchlings surviving 10-15 days post-hatch, 4) number of nestlings produced, and 5) factors of offspring mortality in nests of Black-crowned Night Heron (Nycticorax nycticorax), Snowy Egret (Egretta thula), Cattle Egret (Bubulcus ibis), and Glossy Ibis (Plegadisfalcinellus). We randomly selected 30-50 nests of each species (as available) for study at colonies in Delaware Bay (1993-1998), New York Harbor (1986-1994), Cape Cod (1990-94), and Boston Harbor (1993-94). In addition, we recorded abundance of nesting wading birds and avian predators in most years of study. Colony size ranged from 120-8,300 nests. Clutch size of all species was greater at northern-most sites. Loss of eggs varied between estuaries for all species except Glossy Ibis. Hatching success ranged from 75-88% and differed between estuaries for Black-crowned Night Heron and Glossy Ibis. Hatchling survival ranged from 16-87% and was lowest in Delaware Bay for all species. Nestling production was lowest in Delaware Bay for all species. In general, predation was high in Delaware Bay and egg inviability was high in Boston Harbor. Predation of nestlings was greatest in Delaware Bay for Cattle Egret, but there were no differences between estuaries for other species. Proportions of avian predators to nesting herons did not explain high predation rates in Delaware Bay. Received 18 April 2001, accepted 21June 2001.
{"title":"Regional Patterns of Wading Bird Productivity in Northeastern U.S. Estuaries","authors":"K. Parsons, S. R. Schmidt, A. Matz","doi":"10.2307/1522062","DOIUrl":"https://doi.org/10.2307/1522062","url":null,"abstract":"-We investigated wading bird productivity in four estuaries from Delaware Bay to Boston Harbor in northeastern U.S.A. over the period 1986-1998. To document and characterize reproductive performance of numerically dominant species for use in wildlife and habitat management planning, we recorded 1) number of eggs laid, 2) percent of eggs hatched, 3) percent of hatchlings surviving 10-15 days post-hatch, 4) number of nestlings produced, and 5) factors of offspring mortality in nests of Black-crowned Night Heron (Nycticorax nycticorax), Snowy Egret (Egretta thula), Cattle Egret (Bubulcus ibis), and Glossy Ibis (Plegadisfalcinellus). We randomly selected 30-50 nests of each species (as available) for study at colonies in Delaware Bay (1993-1998), New York Harbor (1986-1994), Cape Cod (1990-94), and Boston Harbor (1993-94). In addition, we recorded abundance of nesting wading birds and avian predators in most years of study. Colony size ranged from 120-8,300 nests. Clutch size of all species was greater at northern-most sites. Loss of eggs varied between estuaries for all species except Glossy Ibis. Hatching success ranged from 75-88% and differed between estuaries for Black-crowned Night Heron and Glossy Ibis. Hatchling survival ranged from 16-87% and was lowest in Delaware Bay for all species. Nestling production was lowest in Delaware Bay for all species. In general, predation was high in Delaware Bay and egg inviability was high in Boston Harbor. Predation of nestlings was greatest in Delaware Bay for Cattle Egret, but there were no differences between estuaries for other species. Proportions of avian predators to nesting herons did not explain high predation rates in Delaware Bay. Received 18 April 2001, accepted 21June 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130250409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
-We examined the flexibility in feeding ecology of Steller's Eider (Polysticta stelleri) by comparing its diet to the taxonomically relatively close Long-tailed Duck (Clangula hyemalis) during two winter periods (early and late) when the two species occurred together. Steller's Eider generally fed on the same type of prey in early and late winter, with a dietary overlap of 43% between the two periods (57% among shelled prey). The mean number of prey species per bird was 7.8 in both early winter and late winter. In contrast, the Long-tailed Duck changed completely from feeding on benthic invertebrates in early winter to spawning Capelin (Mallotus villosus) in late winter. The dietary overlap between the two bird species was 38% in early winter. In early winter, the mean number of prey species was 5.5 in the Long-tailed Duck, and not significantly different from the Steller's Eider. Steller's Eider seemed to be restricted to small prey, both compared to availability of sizes and also to the prey size taken by the Long-tailed Duck. Thus the worldwide rare Steller's Eider seems to be a specialist with limited ability to exploit different food resources, while the numerous Long-tailed Duck is an opportunistic generalist. Low flexibility in feeding ecology indicates that winter habitats for Steller's Eider may be limited, and protection of these areas would probably benefit the species. Received 28June 2001, accepted 25 August 2001.
{"title":"Comparative Feeding Ecology of Steller's Eider and Long-Tailed Ducks in Winter","authors":"J. O. Bustnes, Geir H. R. Systad","doi":"10.2307/1522072","DOIUrl":"https://doi.org/10.2307/1522072","url":null,"abstract":"-We examined the flexibility in feeding ecology of Steller's Eider (Polysticta stelleri) by comparing its diet to the taxonomically relatively close Long-tailed Duck (Clangula hyemalis) during two winter periods (early and late) when the two species occurred together. Steller's Eider generally fed on the same type of prey in early and late winter, with a dietary overlap of 43% between the two periods (57% among shelled prey). The mean number of prey species per bird was 7.8 in both early winter and late winter. In contrast, the Long-tailed Duck changed completely from feeding on benthic invertebrates in early winter to spawning Capelin (Mallotus villosus) in late winter. The dietary overlap between the two bird species was 38% in early winter. In early winter, the mean number of prey species was 5.5 in the Long-tailed Duck, and not significantly different from the Steller's Eider. Steller's Eider seemed to be restricted to small prey, both compared to availability of sizes and also to the prey size taken by the Long-tailed Duck. Thus the worldwide rare Steller's Eider seems to be a specialist with limited ability to exploit different food resources, while the numerous Long-tailed Duck is an opportunistic generalist. Low flexibility in feeding ecology indicates that winter habitats for Steller's Eider may be limited, and protection of these areas would probably benefit the species. Received 28June 2001, accepted 25 August 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124558157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
-Dalmatian Pelicans (Pelecanus crispus) in Lake Mikri Prespa nest on islands of Common Reed (Phragmites) rhizomes formed at the interface between marsh and open water and mostly ranging from 6-80 m2 in area. Nest density from 1984 to 1996 varied from 0.12 to 1.2 nests/m2. Large islands were not more densely occupied than smaller ones. Higher nest densities were observed in the second and third year that a site was used. Islands used for nesting were degraded by weather, water and use by the birds and shrank in size by 1-55% each year; thus some were abandoned and new ones colonized each year. On the average, sites were used for three years in succession, but initially larger sites were used much longer. Nest site quality was related to island rigidity and the availability of nesting material on it. Numbers of breeding pelicans at Prespa are probably limited by the availability of suitable nest sites and, especially, larger islands, since breeding success is positively correlated with the mean nesting assemblage size (number of breeding attempts/number of sites). Artificial nesting rafts are likely to be more successful the more their features comply with the above findings and the more they enhance overall colony compactness. Received 15 April 2001, accepted 18 August 2001.
{"title":"Nesting Habitat Characteristics and Breeding Performance of Dalmatian Pelicans in Lake Mikri Prespa, NW Greece","authors":"G. Catsadorakis, A. Crivelli","doi":"10.2307/1522069","DOIUrl":"https://doi.org/10.2307/1522069","url":null,"abstract":"-Dalmatian Pelicans (Pelecanus crispus) in Lake Mikri Prespa nest on islands of Common Reed (Phragmites) rhizomes formed at the interface between marsh and open water and mostly ranging from 6-80 m2 in area. Nest density from 1984 to 1996 varied from 0.12 to 1.2 nests/m2. Large islands were not more densely occupied than smaller ones. Higher nest densities were observed in the second and third year that a site was used. Islands used for nesting were degraded by weather, water and use by the birds and shrank in size by 1-55% each year; thus some were abandoned and new ones colonized each year. On the average, sites were used for three years in succession, but initially larger sites were used much longer. Nest site quality was related to island rigidity and the availability of nesting material on it. Numbers of breeding pelicans at Prespa are probably limited by the availability of suitable nest sites and, especially, larger islands, since breeding success is positively correlated with the mean nesting assemblage size (number of breeding attempts/number of sites). Artificial nesting rafts are likely to be more successful the more their features comply with the above findings and the more they enhance overall colony compactness. Received 15 April 2001, accepted 18 August 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117340590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Mallory, H. Gilchrist, S. Jamieson, G. Robertson, D. Campbell
-In October 1999, approximately 110 King Eiders (Somateria spectabilis) were found on the ground in the middle of Baffin Island, indicating that these birds had been following an overland migration. The composition of the flock was mixed in both sex (44% female, 56% male) and age of birds (62% hatch year, 38% after hatch year). Approximately 40 birds flew off after resting for six days on the frozen ground. Of the remaining birds that died, predators ate about 15, and 55 were recovered by staff from a local radar site. All eider carcasses carried fat reserves, although there were differences in body mass related to age and sex. Most birds had injuries consistent with crashing into an object at high speed, but in the absence of any obvious vertical obstacles in this region, it appears that this flock flew into the ground during conditions of poor visibility, perhaps facilitated by the formation of cataracts in their eyes. Received 28June 2001, accepted 17 August 2001.
{"title":"Unusual Migration Mortality of King Eiders in Central Baffin Island","authors":"M. Mallory, H. Gilchrist, S. Jamieson, G. Robertson, D. Campbell","doi":"10.2307/1522082","DOIUrl":"https://doi.org/10.2307/1522082","url":null,"abstract":"-In October 1999, approximately 110 King Eiders (Somateria spectabilis) were found on the ground in the middle of Baffin Island, indicating that these birds had been following an overland migration. The composition of the flock was mixed in both sex (44% female, 56% male) and age of birds (62% hatch year, 38% after hatch year). Approximately 40 birds flew off after resting for six days on the frozen ground. Of the remaining birds that died, predators ate about 15, and 55 were recovered by staff from a local radar site. All eider carcasses carried fat reserves, although there were differences in body mass related to age and sex. Most birds had injuries consistent with crashing into an object at high speed, but in the absence of any obvious vertical obstacles in this region, it appears that this flock flew into the ground during conditions of poor visibility, perhaps facilitated by the formation of cataracts in their eyes. Received 28June 2001, accepted 17 August 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128843984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
From 1989 to 1999,1 examined intra-seasonal and annual changes in the abundance and local dis tribution of two groups ofwintering Dunlin (Calidris alpina) occupying different positions along hydrographic gra dients in the Tomales Bay estuary, California. Reciprocal translocation of color-banded Dunlin indicated a discrete separation of wintering Dunlin between the north and south of Tomales Bay. Local abundance in both groups was significantly associated with cumulative seasonal rainfall within and among years. Increased variation in annual and intra-seasonal abundance was related to reduced tidal circulation, greater freshwater stream flow, and increased sa linity variation. On average, winter Dunlin use peaked later but declined earlier in the southern part of the bay (near the head of the bay) than in the northern part of the bay (near the mouth of the bay), Shifts in distribution associated with changes in hydrographic conditions and weather revealed consistent intra-seasonal changes in hab itat preference on temporal scales other than tidal cycles. In the northern part of the bay, changes in habitat pref erence by Dunlin corresponded to thresholds of 20-25 cm cumulative rainfall and 0.5-1.0 m" sec" stream flow, whereas in the south bay changes were relatively continuous. Rainfall, wind velocity and direction, and temperature also influenced habitat preferences. Flocking beha~or dominated over habitat choice at low levels of Dunlin abun dance, resulting in contrasting patterns of habitat use relative to overall trends. These patterns suggested the loss of habitat quality as the criterion for patch use. In general, this study indicates that winter shorebird use of temper ate estuaries can be predicted by differences in weather and hydrographic regimes, including rates and variances of freshwater inflow, estuarine circulation, and water residence times unique to each system. Received 4 February
{"title":"Hydrographic Correlates of Winter Dunlin Abundance and Distribution in a Temperate Estuary","authors":"J. Kelly","doi":"10.2307/1522061","DOIUrl":"https://doi.org/10.2307/1522061","url":null,"abstract":"From 1989 to 1999,1 examined intra-seasonal and annual changes in the abundance and local dis tribution of two groups ofwintering Dunlin (Calidris alpina) occupying different positions along hydrographic gra dients in the Tomales Bay estuary, California. Reciprocal translocation of color-banded Dunlin indicated a discrete separation of wintering Dunlin between the north and south of Tomales Bay. Local abundance in both groups was significantly associated with cumulative seasonal rainfall within and among years. Increased variation in annual and intra-seasonal abundance was related to reduced tidal circulation, greater freshwater stream flow, and increased sa linity variation. On average, winter Dunlin use peaked later but declined earlier in the southern part of the bay (near the head of the bay) than in the northern part of the bay (near the mouth of the bay), Shifts in distribution associated with changes in hydrographic conditions and weather revealed consistent intra-seasonal changes in hab itat preference on temporal scales other than tidal cycles. In the northern part of the bay, changes in habitat pref erence by Dunlin corresponded to thresholds of 20-25 cm cumulative rainfall and 0.5-1.0 m\" sec\" stream flow, whereas in the south bay changes were relatively continuous. Rainfall, wind velocity and direction, and temperature also influenced habitat preferences. Flocking beha~or dominated over habitat choice at low levels of Dunlin abun dance, resulting in contrasting patterns of habitat use relative to overall trends. These patterns suggested the loss of habitat quality as the criterion for patch use. In general, this study indicates that winter shorebird use of temper ate estuaries can be predicted by differences in weather and hydrographic regimes, including rates and variances of freshwater inflow, estuarine circulation, and water residence times unique to each system. Received 4 February","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"476 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117024002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Jovani, J. Tella, M. Forero, M. Bertellotti, G. Blanco, O. Ceballos, J. Donázar
-The geographic and specific distribution of avian Haematozoa is poorly understood and much basic information is still needed. Studies of blood parasites in avian communities are scarce despite of their potential for disentangling the relative importance of host-specific and ecological factors shaping blood parasite distributions. Here we present the first study of blood parasites in a breeding community of seabirds by scanning blood smears obtained from 560 birds belonging to 13 species breeding in Patagonia, Argentina. Seven of these species have not been sampled previously for blood parasites. No blood parasites were detected. The scarcity of vectors due to the marine environment and the dry conditions around the colonies is the most plausible hypothesis for explaining the apparent absence of blood parasites in the Patagonian seabird community, although other hypotheses should be examined. Received 12 December 2000, accepted 8 May 2001.
{"title":"Apparent Absence of Blood Parasites in the Patagonian Seabird Community: Is it Related to the Marine Environment?","authors":"R. Jovani, J. Tella, M. Forero, M. Bertellotti, G. Blanco, O. Ceballos, J. Donázar","doi":"10.2307/1522076","DOIUrl":"https://doi.org/10.2307/1522076","url":null,"abstract":"-The geographic and specific distribution of avian Haematozoa is poorly understood and much basic information is still needed. Studies of blood parasites in avian communities are scarce despite of their potential for disentangling the relative importance of host-specific and ecological factors shaping blood parasite distributions. Here we present the first study of blood parasites in a breeding community of seabirds by scanning blood smears obtained from 560 birds belonging to 13 species breeding in Patagonia, Argentina. Seven of these species have not been sampled previously for blood parasites. No blood parasites were detected. The scarcity of vectors due to the marine environment and the dry conditions around the colonies is the most plausible hypothesis for explaining the apparent absence of blood parasites in the Patagonian seabird community, although other hypotheses should be examined. Received 12 December 2000, accepted 8 May 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122175749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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