M. Davis, T. Simons, M. Groom, J. Weaver, Jeff Cordes
-We studied American Oystercatchers (Haematopus palliatus) by examining reproductive success and the factors affecting it at one location, and by examining the status and trends of breeding population numbers from Florida to Nova Scotia on the east coast of North America. We conducted our field research on Cape Lookout National Seashore, Carteret County, North Carolina from 1997 to 1999, and we documented larger scale breeding population trends by contacting state biologists and reviewing the literature and historical accounts. Presence of eggs and young were checked two to five times per week (by observing from a distance), and efforts were made to determine the reasons for loss of the nest contents. We monitored a total of 245 nests and found low productivity. At least one egg in 32 (13%) nests hatched and one or more chicks fledged from 12 broods. Overall, 14 chicks successfully fledged (nine from North Core Banks and five from South Core Banks) during the three years of the study. Of the 213 clutches that did not hatch, 163 (76%) failed because of predation, and 46 (22%) because of overwash or severe weather. Our minimum estimate for the number of oystercatchers breeding along the entire Atlantic coast and the Gulf coast of Florida is 1,624 pairs. North of Virginia, numbers appear to be stable or slowly increasing and the species has expanded as far north as Cape Sable Island in Nova Scotia. From Virginia south, breeding numbers show a decline in recent years. The number of oystercatchers breeding on barrier islands in Virginia has decreased by more than 50% in the last 20 years. Given their relatively small numbers and inherently low productivity, American Oystercatchers are at risk in rapidly changing coastal ecosystems. Received 1 June 2000, accepted 11 October 2000.
{"title":"The Breeding Status of the American Oystercatcher on the East Coast of North America and Breeding Success in North Carolina","authors":"M. Davis, T. Simons, M. Groom, J. Weaver, Jeff Cordes","doi":"10.2307/1522030","DOIUrl":"https://doi.org/10.2307/1522030","url":null,"abstract":"-We studied American Oystercatchers (Haematopus palliatus) by examining reproductive success and the factors affecting it at one location, and by examining the status and trends of breeding population numbers from Florida to Nova Scotia on the east coast of North America. We conducted our field research on Cape Lookout National Seashore, Carteret County, North Carolina from 1997 to 1999, and we documented larger scale breeding population trends by contacting state biologists and reviewing the literature and historical accounts. Presence of eggs and young were checked two to five times per week (by observing from a distance), and efforts were made to determine the reasons for loss of the nest contents. We monitored a total of 245 nests and found low productivity. At least one egg in 32 (13%) nests hatched and one or more chicks fledged from 12 broods. Overall, 14 chicks successfully fledged (nine from North Core Banks and five from South Core Banks) during the three years of the study. Of the 213 clutches that did not hatch, 163 (76%) failed because of predation, and 46 (22%) because of overwash or severe weather. Our minimum estimate for the number of oystercatchers breeding along the entire Atlantic coast and the Gulf coast of Florida is 1,624 pairs. North of Virginia, numbers appear to be stable or slowly increasing and the species has expanded as far north as Cape Sable Island in Nova Scotia. From Virginia south, breeding numbers show a decline in recent years. The number of oystercatchers breeding on barrier islands in Virginia has decreased by more than 50% in the last 20 years. Given their relatively small numbers and inherently low productivity, American Oystercatchers are at risk in rapidly changing coastal ecosystems. Received 1 June 2000, accepted 11 October 2000.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129121518","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}
--Although the Marbled Murrelet (Brachyramphus marmoratus) usually nests in mature coniferous trees throughout most of its range, in south-central Alaska Marbled Murrelet nests have been found on the ground in unforested areas as frequently as they have been found in older-aged forests. Because ground nests are typically found serendipitously, the relative occurrence of ground nesting is unknown. Further, the importance of unforested habitat to nesting murrelets is unknown. Comparing murrelet dawn activity (related to breeding activity) in forested and unforested habitats in the Kenai Fjords National Park, Alaska inJuly, 1993, we found that the number of inland murrelet "detections" was appreciably and significantly higher in forested than in unforested habitat (forested stations: x = 48.1 detections per station, SE + 7.7; unforested stations: x = 17.4, SE ? 4.0). Visual observations of murrelets flying close to the ground or trees are indicators of nesting, and were much more frequently observed in forested areas. Within unforested areas, murrelet land-use may be related to the amount of low vegetation and shrubs, as stations with more vegetation had higher dawn activity. These data suggest that, although Marbled Murrelets nest on unforested ground in south-central Alaska, forested habitat is much more heavily occupied than unforested habitat. We propose that habitat devoid of older-aged coniferous forest is suboptimal due to the shortage of nest sites that are as protected from predators and weather as those provided by the 3-dimensional structure of mature trees and older-aged forests. Received 4 May 2000, accepted 30July 2000.
尽管大理石纹小燕子(Brachyramphus marmoratus)通常在其大部分活动范围内的成熟针叶树上筑巢，但在阿拉斯加中南部，在未森林地区的地面上发现了大理石纹小燕子的巢穴，其频率与在老森林中发现的频率一样高。因为地面筑巢通常是偶然发现的，所以地面筑巢的相对发生率是未知的。此外，未被森林覆盖的栖息地对小海雀筑巢的重要性尚不清楚。1993年7月，我们比较了阿拉斯加基奈峡湾国家公园有林和无林生境中小天鹅的黎明活动(与繁殖活动有关)，发现有林生境的内陆小天鹅“探测”数量明显高于无林生境(有林站点:x = 48.1个/站，SE + 7.7;未森林站点:x = 17.4, SE ?4.0)。在靠近地面或树木的地方飞行的小海雀的目视观察是筑巢的标志，在森林地区更经常观察到。在非森林地区，小海雀的土地利用可能与低植被和灌木的数量有关，因为植被较多的站具有较高的黎明活动。这些数据表明，尽管大理石纹小海鼠在阿拉斯加中南部的无森林地区筑巢，但有森林的栖息地比无森林的栖息地被占用得更多。我们认为，由于缺乏像成熟树木和古树林的三维结构所提供的那样免受捕食者和天气影响的筑巢地点，缺乏古树针叶林的栖息地是次优的。2000年5月4日收稿，2000年7月30日收稿。
{"title":"Use of Treeless and Forested Habitat by Marbled Murrelets in South-Central Alaska","authors":"D. Marks, Kathy J. Kuletz","doi":"10.2307/1522025","DOIUrl":"https://doi.org/10.2307/1522025","url":null,"abstract":"--Although the Marbled Murrelet (Brachyramphus marmoratus) usually nests in mature coniferous trees throughout most of its range, in south-central Alaska Marbled Murrelet nests have been found on the ground in unforested areas as frequently as they have been found in older-aged forests. Because ground nests are typically found serendipitously, the relative occurrence of ground nesting is unknown. Further, the importance of unforested habitat to nesting murrelets is unknown. Comparing murrelet dawn activity (related to breeding activity) in forested and unforested habitats in the Kenai Fjords National Park, Alaska inJuly, 1993, we found that the number of inland murrelet \"detections\" was appreciably and significantly higher in forested than in unforested habitat (forested stations: x = 48.1 detections per station, SE + 7.7; unforested stations: x = 17.4, SE ? 4.0). Visual observations of murrelets flying close to the ground or trees are indicators of nesting, and were much more frequently observed in forested areas. Within unforested areas, murrelet land-use may be related to the amount of low vegetation and shrubs, as stations with more vegetation had higher dawn activity. These data suggest that, although Marbled Murrelets nest on unforested ground in south-central Alaska, forested habitat is much more heavily occupied than unforested habitat. We propose that habitat devoid of older-aged coniferous forest is suboptimal due to the shortage of nest sites that are as protected from predators and weather as those provided by the 3-dimensional structure of mature trees and older-aged forests. Received 4 May 2000, accepted 30July 2000.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125288864","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. Fasola, Ying-mei Zhang, Dongqing Zhao, Y. Dong, Hui Wang
-Age-assortative mating occurs frequently in birds, and may be produced by active selection for older and more successful mates, but also simply by age-related differences in breeding time, or by mate fidelity, without age-related selection. We describe the occurrence of age-assortative breeding in the Black-crowned Night Heron (Nycticorax nycticorax) near Wuxi, China. Throughout the whole breeding season, 59% of the breeders were adults i.e., birds older than two years, and 41% were younger birds injuvenile plumage i.e., birds in their second year. Most of 206 pairs were strictly assorted by age, and only 2.4% had one adult and one juvenile. A part of this assortment was due to age-related differences in the breeding period, but even when this seasonality is accounted for, the observed frequency of mixed pairs is much lower than expected. Mate fidelity is not likely to account for the observed assortment. We conclude that the strict age assortment we observed in Black-crowned Night Herons is to be ascribed to active mate selection by age. Reproductive success was higher for pairs of adults than for those in juvenile plumage, while no difference was found for egg size, chick condition or asymmetry. Pairing between adults may therefore be adaptive because it enhances reproductive success. The high frequency of Black-crowned Night Herons breeding in juvenile plumage in China (41%) contrasts sharply with the situation in other parts of the species range, where birds injuvenile plumage rarely breed, are even seldom seen near colonies, and are believed to remain in their wintering areas. Received 2 February 2001, accepted 25 March 2001.
{"title":"Age-Assortative Mating Related to Reproductive Success in Black-Crowned Night Herons","authors":"M. Fasola, Ying-mei Zhang, Dongqing Zhao, Y. Dong, Hui Wang","doi":"10.2307/1522041","DOIUrl":"https://doi.org/10.2307/1522041","url":null,"abstract":"-Age-assortative mating occurs frequently in birds, and may be produced by active selection for older and more successful mates, but also simply by age-related differences in breeding time, or by mate fidelity, without age-related selection. We describe the occurrence of age-assortative breeding in the Black-crowned Night Heron (Nycticorax nycticorax) near Wuxi, China. Throughout the whole breeding season, 59% of the breeders were adults i.e., birds older than two years, and 41% were younger birds injuvenile plumage i.e., birds in their second year. Most of 206 pairs were strictly assorted by age, and only 2.4% had one adult and one juvenile. A part of this assortment was due to age-related differences in the breeding period, but even when this seasonality is accounted for, the observed frequency of mixed pairs is much lower than expected. Mate fidelity is not likely to account for the observed assortment. We conclude that the strict age assortment we observed in Black-crowned Night Herons is to be ascribed to active mate selection by age. Reproductive success was higher for pairs of adults than for those in juvenile plumage, while no difference was found for egg size, chick condition or asymmetry. Pairing between adults may therefore be adaptive because it enhances reproductive success. The high frequency of Black-crowned Night Herons breeding in juvenile plumage in China (41%) contrasts sharply with the situation in other parts of the species range, where birds injuvenile plumage rarely breed, are even seldom seen near colonies, and are believed to remain in their wintering areas. Received 2 February 2001, accepted 25 March 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131161183","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}
{"title":"Double-Brooding in the Boat-Billed Heron","authors":"Jaime A. Gómez, J. Gil-Delgado, J. S. Monrós","doi":"10.2307/1522043","DOIUrl":"https://doi.org/10.2307/1522043","url":null,"abstract":"","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125343678","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}
{"title":"Contributions to the History of North American Ornithology, Volume II","authors":"D. Nettleship, W. Davis, J. A. Jackson","doi":"10.2307/1522051","DOIUrl":"https://doi.org/10.2307/1522051","url":null,"abstract":"","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131953931","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 studied seven species of waterbirds that nested on Isla Montague, Mexico, at the mouth of the Colorado River, during the 1993 and 1994 breeding seasons: Great Blue Heron (Ardea herodias), Snowy Egret (Egretta thula), Black-crowned Night Heron (Nycticorax nycticorax), Laughing Gull (Larus atricilla), Least Tern (Sterna antillarum), Gull-billed Tern (Sterna nilotica), and Black Skimmer (Rynchops niger). Breeding occurred along several tidal channels of the Estero del Chayo and on shell mounds near the lighthouse. There were low levels of predation, by at least one Coyote (Canis latrans), and unknown, but likely avian, predators. Tidal inundation was the major factor affecting the nesting of the birds, as it destroyed almost all nests, eggs and chicks on at least five occasions during one breeding season. It seems likely that the pattern of inundations we recorded does not happen all years. Received 21 August 2000, accepted 20 March 2001.
{"title":"Nesting Waterbirds of Isla Montague, Northern Gulf of California, Mexico: Loss of Eggs Due to Predation and Flooding, 1993-1994","authors":"Elisa Peresbarbosa, E. Mellink","doi":"10.2307/1522040","DOIUrl":"https://doi.org/10.2307/1522040","url":null,"abstract":"-We studied seven species of waterbirds that nested on Isla Montague, Mexico, at the mouth of the Colorado River, during the 1993 and 1994 breeding seasons: Great Blue Heron (Ardea herodias), Snowy Egret (Egretta thula), Black-crowned Night Heron (Nycticorax nycticorax), Laughing Gull (Larus atricilla), Least Tern (Sterna antillarum), Gull-billed Tern (Sterna nilotica), and Black Skimmer (Rynchops niger). Breeding occurred along several tidal channels of the Estero del Chayo and on shell mounds near the lighthouse. There were low levels of predation, by at least one Coyote (Canis latrans), and unknown, but likely avian, predators. Tidal inundation was the major factor affecting the nesting of the birds, as it destroyed almost all nests, eggs and chicks on at least five occasions during one breeding season. It seems likely that the pattern of inundations we recorded does not happen all years. Received 21 August 2000, accepted 20 March 2001.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131341571","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}
-Twenty-one American White Pelicans (Pelecanus erythrorhynchos) were captured and fitted with radiotransmitters in south Louisiana and the delta region of Mississippi during the winter and early spring of 1994-1997. The pelicans were monitored to determine their daily activity budgets while using different habitats such as catfish ponds, crawfish ponds, rivers, lakes, and bayous. Pelicans foraging at catfish ponds spent about 4% of their day foraging and 96% loafing, while pelicans foraging in other habitats spent about 28% of their day foraging and 72% loafing. For an individual bird, the mean number of foraging sessions per day was 2.5 (? 0.53 SE) and the mean length of each foraging session was 66.7 min. (?8.08 SE). Aerial censuses were also conducted to determine the numbers of pelicans in the delta region of Mississippi. Each year the numbers of pelicans wintering in the delta region of Mississippi peaked in February and March, corresponding with spring migration. Pelican numbers reached approximately 4,600 during February and March 1996. Pelicans were observed foraging in larger flocks for shorter periods of time on catfish ponds than in other habitats. Received 27 September 2000, accepted 28 November 2000.
- 1994-1997年冬季和初春期间，在路易斯安那州南部和密西西比州三角洲地区捕获了21只美国白鹈鹕(pelenanus erythrorhynchos)并安装了无线电发射机。研究人员对鹈鹕进行了监测，以确定它们在不同栖息地(如鲶鱼池塘、小龙虾池塘、河流、湖泊和河口)的日常活动预算。在鲶鱼池塘觅食的鹈鹕一天中大约有4%的时间在觅食，96%的时间在闲逛，而在其他栖息地觅食的鹈鹕一天中大约有28%的时间在觅食，72%的时间在闲逛。对于一只鸟来说，每天觅食的平均次数是2.5次(?0.53 SE)，平均每次觅食时长为66.7 min (- 8.08 SE)。还进行了空中普查，以确定密西西比三角洲地区鹈鹕的数量。每年在密西西比三角洲地区越冬的鹈鹕数量在2月和3月达到顶峰，与春季迁徙相对应。1996年2月和3月，鹈鹕的数量达到了大约4 600只。观察到鹈鹕在鲶鱼池塘上觅食的时间比在其他栖息地要短。2000年9月27日收，2000年11月28日收。
{"title":"Daily Activity Budgets and Population Size of American White Pelicans Wintering in South Louisiana and the Delta Region of Mississippi","authors":"D. King, Scott J. Werner","doi":"10.2307/1522038","DOIUrl":"https://doi.org/10.2307/1522038","url":null,"abstract":"-Twenty-one American White Pelicans (Pelecanus erythrorhynchos) were captured and fitted with radiotransmitters in south Louisiana and the delta region of Mississippi during the winter and early spring of 1994-1997. The pelicans were monitored to determine their daily activity budgets while using different habitats such as catfish ponds, crawfish ponds, rivers, lakes, and bayous. Pelicans foraging at catfish ponds spent about 4% of their day foraging and 96% loafing, while pelicans foraging in other habitats spent about 28% of their day foraging and 72% loafing. For an individual bird, the mean number of foraging sessions per day was 2.5 (? 0.53 SE) and the mean length of each foraging session was 66.7 min. (?8.08 SE). Aerial censuses were also conducted to determine the numbers of pelicans in the delta region of Mississippi. Each year the numbers of pelicans wintering in the delta region of Mississippi peaked in February and March, corresponding with spring migration. Pelican numbers reached approximately 4,600 during February and March 1996. Pelicans were observed foraging in larger flocks for shorter periods of time on catfish ponds than in other habitats. Received 27 September 2000, accepted 28 November 2000.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122184149","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}
{"title":"Seabirds and Marine Mammals of the Far East (Field Guide)","authors":"D. Nettleship, Yura B. Artukhin, V. Burkanov","doi":"10.2307/1522050","DOIUrl":"https://doi.org/10.2307/1522050","url":null,"abstract":"","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127395324","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}
-Common Eider (Somateria mollissima) ducklings and associated females in the Bay of Fundy feed extensively on invertebrates found in association with Knotted Wrack (Ascophyllum nodosum), commonly referred to as rockweed. To assess whether commercial harvest of rockweed, which is occurring in New Brunswick, might adversely affect ducklings, I examined their feeding behavior in relation to rockweed availability and duckling age. Ducklings fed in rockweed whenever it was available. Young ducklings (less than 3 weeks old) spent more time dabbling for invertebrates in the floating rockweed canopy and less time diving than did older birds. Young ducklings fed when rockweed was most available at the surface, whereas rockweed availability had no effect on the feeding rate of older ducklings. When rockweed was unavailable, older ducklings dove for food, while younger birds still attempted some dabbling. These results suggest that if rockweed harvest lowers the canopy height and reduces the time during each tidal cycle that algae floats at the surface, it might adversely affect Common Eider ducklings during the first weeks of life, when they are less able to dive for food. Consequently, in areas where ducklings feed regularly, care should be taken during harvesting to avoid changing the height and structure of the rockweed canopy. Similarly, harvesters should avoid disturbing foraging ducklings, because it could increase the already high predation risk that these birds face in their first few weeks of life. Received 10 March 2000, accepted 16 November 2000.
{"title":"Feeding Behavior of Common Eider Ducklings in Relation to Availability of Rockweed Habitat and Duckling Age","authors":"D. Hamilton","doi":"10.2307/1522035","DOIUrl":"https://doi.org/10.2307/1522035","url":null,"abstract":"-Common Eider (Somateria mollissima) ducklings and associated females in the Bay of Fundy feed extensively on invertebrates found in association with Knotted Wrack (Ascophyllum nodosum), commonly referred to as rockweed. To assess whether commercial harvest of rockweed, which is occurring in New Brunswick, might adversely affect ducklings, I examined their feeding behavior in relation to rockweed availability and duckling age. Ducklings fed in rockweed whenever it was available. Young ducklings (less than 3 weeks old) spent more time dabbling for invertebrates in the floating rockweed canopy and less time diving than did older birds. Young ducklings fed when rockweed was most available at the surface, whereas rockweed availability had no effect on the feeding rate of older ducklings. When rockweed was unavailable, older ducklings dove for food, while younger birds still attempted some dabbling. These results suggest that if rockweed harvest lowers the canopy height and reduces the time during each tidal cycle that algae floats at the surface, it might adversely affect Common Eider ducklings during the first weeks of life, when they are less able to dive for food. Consequently, in areas where ducklings feed regularly, care should be taken during harvesting to avoid changing the height and structure of the rockweed canopy. Similarly, harvesters should avoid disturbing foraging ducklings, because it could increase the already high predation risk that these birds face in their first few weeks of life. Received 10 March 2000, accepted 16 November 2000.","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"333 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122848990","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}
{"title":"Interspecific Interactions and Nest Building Behavior in Buff-Necked Ibis in the Brazilian Pantanal","authors":"Shannon N. Bouton, T. Bouton","doi":"10.2307/1522047","DOIUrl":"https://doi.org/10.2307/1522047","url":null,"abstract":"","PeriodicalId":266321,"journal":{"name":"Waterbirds: The International Journal of Waterbird Biology","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126864036","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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