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1.
JAMES R. HERKERT 《The Journal of wildlife management》2007,71(8):2749-2751
ABSTRACT Henslow's sparrow (Ammodramus henslowii) is one of North America's fastest declining songbirds. Population declines combined with a small global population have led to heightened conservation concern. I used data from the North American Breeding Bird Survey to assess the impact that the Conservation Reserve Program (CRP) has had on Henslow's sparrows throughout their United States breeding range. My analysis suggests local Henslow's sparrow population trends are correlated with CRP enrollment, with populations increasing more in areas with relatively high local CRP enrollment, and that CRP appears to be playing a significant role in reversing long-term population declines. 相似文献
2.
JAMES R. HERKERT 《The Journal of wildlife management》2007,71(4):1229-1233
Abstract: The Henslow's sparrow (Ammodramus henslowii) is a species of high conservation concern due to long-term population declines and a small global population. Habitat loss is considered to be the most likely cause of Henslow's sparrow declines and the recent establishment of large acreages of undisturbed grasslands through the Conservation Reserve Program is considered to have the potential to benefit populations. I used data from Illinois' Spring Bird Count to estimate recent population trends and examine the association that changes in land-use, especially the establishment of Conservation Reserve Program lands, have had on local Henslow's sparrow population trends. My analysis shows that Henslow's sparrow populations have increased substantially within Illinois, USA over the last 10 years and that this population increase strongly coincides with the establishment of >400,000 ha of grasslands within the state by the Conservation Reserve Program. New rules allowing for managed haying and grazing on Conservation Reserve Program grasslands have the potential to reduce the suitability of program fields for this species and, thus, Henslow's sparrow use of program fields should be monitored as the new rules are implemented. 相似文献
3.
Robert B. Jacobs Frank R. Thompson III Rolf R. Koford Frank A. La Sorte Hope D. Woodward Jane A. Fitzgerald 《The Journal of wildlife management》2012,76(2):372-381
Of 6 million ha of prairie that once covered northern and western Missouri, <36,500 ha remain, with planted, managed, and restored grasslands comprising most contemporary grasslands. Most grasslands are used as pasture or hayfields. Native grasses largely have been replaced by fescue (Festuca spp.) on most private lands (almost 7 million ha). Previously cropped fields set aside under the Conservation Reserve Program (CRP) varied from a mix of cool-season grasses and forbs, or mix of native warm-season grasses and forbs, to simple tall-grass monocultures. We used generalized linear mixed models and distance sampling to assess abundance of 8 species of breeding grassland birds on 6 grassland types commonly associated with farm practices in Missouri and located in landscapes managed for grassland-bird conservation. We selected Bird Conservation Areas (BCAs) for their high percentage of grasslands and grassland-bird species, and for <5% forest cover. We used an information-theoretic approach to assess the relationship between bird abundance and 6 grassland types, 3 measures of vegetative structure, and 2 landscape variables (% grassland and edge density within a 1-km radius). We found support for all 3 levels of model parameters, although there was less support for landscape than vegetation structure effects likely because we studied high-percentage-grassland landscapes (BCAs). Henslow's sparrow (Ammodramus henslowii) counts increased with greater percentage of grassland, vegetation height-density, litter depth, and shrub cover and lower edge density. Henslow's sparrow counts were greatest in hayed native prairie. Dickcissel (Spiza americana) counts increased with greater vegetation height-density and were greatest in planted CRP grasslands. Grasshopper sparrow (A. savannarum) counts increased with lower vegetation height, litter depth, and shrub cover. Based on distance modeling, breeding densities of Henslow's sparrow, dickcissel, and grasshopper sparrow in the 6 grassland types ranged 0.9–2.6, 1.4–3.2, and 0.1–1.5 birds/ha, respectively. We suggest different grassland types and structures (vegetation height, litter depth, shrub cover) are needed to support priority grassland-bird species in Missouri. © 2011 The Wildlife Society. 相似文献
4.
Laura M. Palasz Matthew E. Brooks Philip C Stouffer 《Journal of Field Ornithology》2010,81(2):139-150
ABSTRACT Wintering Henslow's Sparrows (Ammodramus henslowii) are generally associated with open grasslands. Results of small‐scale, regionally specific studies have not revealed larger‐scale abundance patterns, but they have shown regional differences in habitat selection. Our objective was to quantify Henslow's Sparrow abundance and vegetation associations across Louisiana, an area that includes multiple types of grassland habitats. Bird densities in longleaf pine savannas of eastern and western Louisiana were over 1.5 times higher than in northern prairies and over 13 times higher than at a site in southwestern Louisiana. The responses of Henslow's Sparrows to fire differed between eastern and western savannas, with abundance increasing three fold over the first 3 yrs after fire in the west, and decreasing three fold over that interval in the east. In both areas, habitat became unsuitable by about 5 yrs after fire, probably due to woody encroachment and loss of herbaceous plants. For sites that contained Henslow's Sparrows at least once during our study, habitat modeling revealed that neither vegetation structure nor plant species composition was important in predicting the occurrence of Henslow's Sparrows within sites or abundance among sites throughout the state, perhaps due to the variety of habitats sampled. Our results suggest that longleaf pine savannas are the most important grasslands for wintering Henslow's Sparrows in Louisiana and that overwintering habitat is probably selected based on regionally specific vegetation features. Optimal fire intervals may vary regionally, particularly between mesic flatwoods savannas and drier upland savannas, perhaps due to different rates of biomass accumulation. Management for Henslow's Sparrows should be based on region‐specific studies, recognizing that appropriate fire regimes may vary among regions. 相似文献
5.
Henslow's Sparrows (Ammodramus henslowii) are known to breed in restored grasslands consisting of either warm‐ or cool‐season grasses, but additional information is needed concerning their breeding biology in these two types of grasslands. We compared the abundance, territory sizes, and pairing success of male Henslow's Sparrows in grasslands in west‐central Missouri in 2010 and 2011 using a paired‐treatment design, where warm‐ and cool‐season grasslands were located in close proximity. Selection indices indicated no apparent preference by male Henslow's Sparrows for either type of grassland, and the territory sizes and pairing success of males in cool‐ and warm‐season grasslands did not differ. In addition, we found no significant differences in habitat structure between these grassland types. Thus, our results suggest that the warm‐ and cool‐season grasslands in our study provided suitable habitat for Henslow's Sparrows. Other investigators have drawn similar conclusions for Henslow's Sparrows and for grassland birds in general, with the structural characteristics and, for some species, the size of grasslands being more important for grassland birds than plant species composition. 相似文献
6.
Marissa A. Ahlering Douglas H. Johnson John Faaborg 《Journal of Field Ornithology》2006,77(4):365-371
ABSTRACT. Territorial songbirds generally use song to defend territories and attract mates, but conspecific song may also serve as a cue to attract other male songbirds to a breeding site. Although known to occur in some colonial and forest-associated species, only recently have investigators examined conspecific attraction in grassland species. We used a playback experiment to examine the possible role of conspecific attraction for males searching for potentially suitable breeding habitat in a grassland specialist, the Baird's Sparrow ( Ammodramus bairdii ). Experimental playback plots and control plots with similar landscape and vegetation characteristics were established at two sites in North Dakota. Baird's Sparrows colonized three of six experimental plots and none of six control plots. Males on experimental plots established territories adjacent to the playback stations and were sometimes observed counter-singing with the playback of conspecific songs. Vegetation characteristics were similar on all study plots, and did not explain differences in bird density on our treatment plots. Although we found that playback of conspecific songs attracted male Baird's Sparrows to previously unoccupied, potentially suitable habitat, further experiments are needed to examine the importance of conspecific attraction relative to other cues that birds may use, such as vegetation features. The conservation and management implications of conspecific attraction are not completely understood, but the presence of conspecifics should be considered as a potential cue in habitat selection by all species of birds. 相似文献
7.
Alberto Macías‐Duarte Arvind O. Panjabi Erin H. Strasser Greg J. Levandoski Irene Ruvalcaba‐Ortega Paul F. Doherty Carmen I. Ortega‐Rosas 《Journal of Field Ornithology》2017,88(4):374-386
Populations of grassland birds that overwinter in the Chihuahuan Desert are declining more rapidly than other grassland birds, and survival during the non‐breeding season may have a strong influence on population trends of these species. Habitat loss and deterioration due to desertification may be contributing to these declines, and the winter ecology of grassland birds under these changing environmental conditions remains relatively unexplored. To fill this information gap, we estimated the survival of two grassland‐obligate sparrows, Baird's Sparrows (Ammodramus bairdii) and Grasshopper Sparrows (A. savannarum), on their wintering grounds in the Chihuahuan Desert, and investigated the role of habitat structure and weather on survival rates. We deployed radio‐transmitters on Baird's (N = 49) and Grasshopper (N = 126) sparrows near Janos, Chihuahua, and tracked birds from November to March during the winters of 2012–2013 and 2013–2014. Causes of mortality included avian predators, mammals, and possibly weather. We estimated an overall weekly winter survival probability of ? = 92.73% (95% CI[s] = 88.63–95.44%) for Baird's Sparrows in 2012–2013. We estimated a weekly winter survival probability of ? = 93.48% (95% CI[s] = 90.29–96.67%) and ? = 98.78% (95% CI[s] = 97.88–99.68%) for Grasshopper Sparrow in 2012–2013 and 2013–2014, respectively. Weekly winter survival was lower with colder daily minimum temperatures for both species and in areas with taller shrubs for Grasshopper Sparrows, with the shrubs potentially increasing predation risk by providing perches for Loggerhead Shrikes (Lanius ludovicianus). Our results highlight the need to maintain healthy grass structure in wintering areas to provide birds with food, protection from predators, and adequate cover from inclement weather. Our results also demonstrate that the presence of shrubs can lower winter survival, and suggest that shrub encroachment into the winter habitat of these sparrows may be an important driver of their population declines. Shrub removal could increase survival of wintering sparrows in the Chihuahuan Desert by reducing availability of perches for avian predators, thus reducing predation risk. 相似文献
8.
William C. Holimon Jennifer A. Akin William H. Baltosser Catherine W. Rideout C. Theo Witsell 《Journal of Field Ornithology》2012,83(4):351-361
ABSTRACT Smith's Longspurs (Calcarius pictus) are a species of concern in North America because of their limited range and apparent low population size. To better understand winter habitat needs and guide management of this species, we examined habitat associations of Smith's Longspurs in eastern Arkansas by comparing grassland patches where Smith's Longspurs flushed to randomly located patches in the same area. Smith's Longspurs were found in sparse grassland patches of relatively low height adjacent to airport runways where the native grass prairie three‐awn (Aristida oligantha) dominated ground cover and vertical structure. Smith's Longspurs were not found in vegetation plots dominated by non‐native Bermuda grass (Cynodon dactylon). Prairie three‐awn grass may provide concealment from predators and their seeds may be an important food source. Occurrence of Smith's Longspurs was also correlated with less litter, perhaps because deeper litter could make walking and searching for seeds more difficult. Availability of suitable habitat for Smith's Longspurs along airport runways may be declining due to natural succession of grassland habitat in the absence of disturbance and recent changes in management that favor Bermuda grass. Conversion and degradation of native prairie has resulted in the decline in abundance and distribution of Chestnut‐collared Longspurs (C. ornatus) and McCown's Longspurs (Rhynchophanes mccownii). Our findings suggest that conversion of native grasslands to non‐native grasslands results in loss and degradation of habitat for wintering populations of Smith's Longspurs. 相似文献
9.
Alexandre A. de Oliveira Alberto Vicentini Jerome Chave Camila de T. Castanho Stuart J. Davies Adriana M. Z. Martini Renato A. F. Lima Ricardo R. Ribeiro Amaia Iribar Vinicius C. Souza 《Journal of Plant Ecology》2014,7(2):134
Aims The coastal Brazilian rainforest on white-sand (restinga) ranks among the most fragmented forest types in the tropics, owing to both the patchy distribution of sandy soils and widespread coastal development activities. Here we study the environmental and evolutionary determinants of a forest tree assemblage at a single restinga forest in Southeastern Brazil. We also explore the ability of competing hypotheses to explain the maintenance of species diversity in this forest type, which includes contrasting extremes of edaphic conditions associated with flooding stress.Methods The study was conducted in a white-sand forest permanent plot of 10.24 ha on the coastal plain of Southeastern Brazil. This plot was divided into 256 quadrats of 20×20 m, which were classified into two main edaphic habitats (flooded and drained). Trees with a diameter ≥1cm at breast height were identified. We assembled DNA sequence data for each of the 116 morphospecies recognized using two chloroplast markers (rbcL and matK). A phylogenetic tree was obtained using the maximum likelihood method, and a phylogenetic distance matrix was produced from an ultrametric tree. We analyzed similarity in floristic composition and structure between habitats and related them to cross-plot distances using permutation procedures. Null model torus shift simulations were performed to obtain a statistical significance level for habitat association for each species. The phylogenetic structure for the two habitats and for each 20×20 m quadrat was calculated using the mean phylogenetic distance weighted by species abundance and checked for significance using the standardized effect size generated by 5000 randomizations of phylogenetic tip labels.Important findings Our results indicate that partitioning among edaphic habitats is important for explaining species distributions and coexistence in restinga forests. Species distributions within the plot were found to be non-random: there was greater floristic similarity within than between habitats, and>40% of the more abundant species were positively or negatively associated with at least one habitat. Patterns of habitat association were not independent of phylogenetic relatedness: the community was overdispersed with respect to space and habitat type. Closely related species tended to occur in different habitats, while neighboring trees tended to belong to more distantly related species. We conclude that habitat specialization is important for the coexistence of species in restinga forests and that habitat heterogeneity is therefore an essential factor in explaining the maintenance of diversity of this unique but fragile and threatened type of forest. 相似文献
10.
Overwintering is a key demographic stage for migratory birds but remains poorly understood, especially among multiple declining grassland bird species. The non-breeding ranges all 4 species of longspur (i.e., chestnut-collared [Calcarius ornatus], Smith's [C. pictus], Lapland [C. lapponicus], thick-billed [Rhynchophanes mccownii]) overlap in Oklahoma and the Texas Panhandle, USA, making this region ideal to study their wintering ecology. We evaluated the relationship between wintering longspur occurrence and fine-scale habitat characteristics using a combination of standardized bird surveys and vegetation plot sampling. Our study encompassed large, representative tracts of 3 prairie ecosystems (i.e., shortgrass, mixed-grass, and tallgrass prairies) that intersect within the Southern Great Plains, during winters of 2018–2019 and 2019–2020. Using randomization tests and classification trees, we characterized longspur habitats and compared these associations across the 3 prairie ecosystems. Fine-scale winter habitats (horizontal structure, vertical structure, and species compositions) varied among all 4 longspur species, varied at very fine scales, and differed between grassland types. Our findings can be applied to the management of grasslands such as decreasing vegetation height in mixed-grass prairies for chestnut-collared longspurs or removing woody vegetation in shortgrass prairies for thick-billed longspurs to help develop full-life cycle conservation for longspurs, which have experienced population declines. 相似文献
11.
Theresa Spatz;Jakob Katzenberger;Nicolas Friess;Christian Gelpke;Eckhard Gottschalk;Martin Hormann;Steffen Koschkar;Thomas Pfeiffer;Stefan Stübing;Christoph Sudfeldt;Sascha Rösner;Dana G. Schabo;Nina Farwig; 《Journal of avian biology》2022,2022(10):e02925
Intrinsic and extrinsic drivers shape the space use of wide-ranging raptors. A large proportion of raptors are migrants that shift their activity ranges between summer and winter habitats, where they encounter different environmental conditions. Analysing the effects of intrinsic and extrinsic drivers on the space use in summer and winter habitats provides crucial insights into the ecology of migratory raptors. Here, we investigated the seasonal space use by 43 red kites Milvus milvus tracked by GPS-transmitters across central and south-western Europe over seven consecutive years. We compared space use patterns, i.e. activity range sizes and mean daily distances of the birds between summer and winter, and analysed the influence of extrinsic (landscape diversity, primary productivity) and intrinsic factors (sex). Within summer, we investigated the influence of breeding success and sex on activity range sizes. We further analysed differences in habitat availability and habitat selection between seasons. We found that space use was smaller in summers than in winters. When compared to those of males, activity ranges of female red kites were larger in summers and smaller in winters, with shorter mean daily distances in both seasons. Within summer, successfully breeding red kites had smaller activity range sizes in both sexes, but this effect was stronger in females than in males. Regardless of the season, landscape diversity was positively correlated with space use, whereas primary productivity was negatively correlated with it. The habitat use differed between seasons, with agricultural landscapes being less proportionally used in summers than in winters. Overall, we showed that both intrinsic and extrinsic drivers shaped space use in both seasons, leading to differences in space use patterns and habitat use in migratory raptors between their summer and winter habitats. Our findings underline the importance of consideration of the entire annual cycle of migratory species for conservation management. 相似文献
12.
Lilian's Lovebird Agapornis lilianae is regarded as a mopane Colophospermum mopane woodland specialist. Its global population is sparse and is spread along the Zambezi valley with little known about its current distribution and status. We explored the current distribution of Lilian's Lovebird in Malawi, and in particular focused on the distribution and habitat associations of the largest resident population in Liwonde National Park (LNP). Local birders and tourist guides provided distribution information from across Malawi. Transect walks were conducted to collect data in LNP. Five new atlas records are reported; three were within 40–56 km of the LNP population and two were over 150 km south and north of LNP, respectively. One of the sites is about 66 km from the Lilian's Lovebird population in Luangwa Valley, Zambia. New national records were evidence of the importance of seasonal movements to the species. Lilian's Lovebirds occurred throughout LNP with the highest abundance in the central section. Seasonal movements to areas outside the park were also recorded. A variety of vegetation types were used by the lovebirds, but the strongest habitat associations were with seasonally wet grasslands and not mopane woodlands as would be expected. Thus, conservation efforts should also include these other habitats. 相似文献
13.
Amy E. M. Johnson T. Scott Sillett David Luther Valentine Herrmann Thomas A. Akre William J. McShea 《The Journal of wildlife management》2019,83(7):1515-1526
Birds that depend on grassland and successional-scrub vegetation communities are experiencing a greater decline than any other avian assemblage in North America. Habitat loss and degradation on breeding and wintering grounds are among the leading causes of these declines. We used public and private lands in northern Virginia, USA, to explore benefits of grassland management and associated field structure on supporting overwintering bird species from 2013 to 2016. Specifically, we used non-metric multidimensional scaling and multispecies occupancy models to compare species richness and habitat associations of grassland-obligate and successional-scrub species during winter in fields comprised of native warm-season grasses (WSG) or non-native cool-season grasses (CSG) that were managed at different times of the year. Results demonstrated positive correlations of grassland-obligate species with decreased vegetation structure and a higher percentage of grass cover, whereas successional-scrub species positively correlated with increased vegetation structure and height and increased percentages of woody stems, forb cover, and bare ground. Fields of WSG supported higher estimated total and target species richness compared to fields of CSG. Estimated species richness was also influenced by management timing, with fields managed during the previous winter or left unmanaged exhibiting higher estimated richness than fields managed in summer or fall. Warm-season grass fields managed in the previous winter or left unmanaged had higher estimated species richness than any other treatment group. This study identifies important winter habitat associations (e.g., vegetation height and field openness) with species abundance and richness and can be used to make inferences about optimal management practices for overwintering avian species in eastern grasslands of North America. © 2019 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. 相似文献
14.
Danielle T. Hudson Chantel E. Markle Lorna I. Harris Paul A. Moore James M. Waddington 《Ecohydrology》2021,14(1)
Lichens and mosses are among the first organisms to colonize the open bedrock of eastern Georgian Bay, Ontario making them essential for primary soil formation and ecosystem succession, while also providing nesting habitat for turtle species‐at‐risk. However, the slow growing nature of lichen and moss makes them vulnerable to ecohydrological stresses caused by climate and land‐use change. In order to better understand how lichen and moss will respond to stressors, we examined which ecohydrological factors (e.g., near‐surface soil moisture and temperature) control the CO2 exchange of lichen (Cladonia spp.) and moss (Polytrichum spp.) on rock barrens, and the time of year growth primarily occurs. Net ecosystem productivity (NEP) was significantly greater in the wet period of the growing season than the dry, with an estimated difference of 0.7 μmol m−2 s−1 for lichen, 2.9 μmol m−2 s−1 for moss, and 2.5 μmol m−2 s−1 for a moss and lichen mix. These findings indicate that the wet portions of the growing season are critical for growth, while lichen and moss have little to no productivity during the dry period. Our results indicate that near‐surface soil moisture is an indicator of the CO2 exchange of lichen and moss, and this relationship varies among cover types. For the geographical regions where warm, dry conditions are expected to increase in duration and frequency with climate change, lichen and moss NEP will likely decrease, thus limiting the long‐term availability of nesting habitat for turtle species‐at‐risk. 相似文献
15.
John Mbaluka Kimeu Geoffrey Mwachala Tammo Reichgelt A. Muthama Muasya 《African Journal of Ecology》2020,58(3):492-502
The phenomenon of sharp boundaries between distinctive vegetation types occurring under the same climatic conditions has often been interpreted by plant ecologists to characterise alternative stable states (ASS). The phenomenon may be relevant in explaining two strikingly different vegetation formations (broad-leaved nonspiny Combretum and fine-leaved spiny Acacia) co-occurring in mesic savannah of southeastern Kenya. We hypothesise that the two vegetation within southeastern Kenya ecosystems represent ASS whose transition may be a response to soil characteristics switch. To explore our hypothesis, we analysed empirical field data of woody species and soil characteristics from 57 plots that included 25 from Combretum and 32 from Acacia vegetation formations. We compared floristic composition and soil characteristics between the two systems and correlated edaphic statuses and vegetation states. We encountered 2,749 woody plant individuals, representing 115 species, 87 genera and 40 families. We found that the two vegetation had discrete woody species composition and soil characteristics, and also a significant species–edaphic association. The results are consistent with the ASS theory demonstrating that soil characteristics are among the important micro-environmental filters driving and maintaining woody vegetation mosaics in the tropics. Importantly, understanding ASS has ramifications for sustainable utilisation of woody plant resources in East African savannahs. 相似文献
16.
Jennifer Walsh Rebecca J. Rowe Brian J. Olsen W. Gregory Shriver Adrienne I. Kovach 《Ecology and evolution》2016,6(1):279-294
Local environmental features can shape hybrid zone dynamics when hybrids are bounded by ecotones or when patchily distributed habitat types lead to a corresponding mosaic of genotypes. We investigated the role of marsh‐level characteristics in shaping a hybrid zone between two recently diverged avian taxa – Saltmarsh (Ammodramus caudacutus) and Nelson's (A. nelsoni) sparrows. These species occupy different niches where allopatric, with caudacutus restricted to coastal marshes and nelsoni found in a broader array of wetland and grassland habitats and co‐occur in tidal marshes in sympatry. We determined the influence of habitat types on the distribution of pure and hybrid sparrows and assessed the degree of overlap in the ecological niche of each taxon. To do this, we sampled and genotyped 305 sparrows from 34 marshes across the hybrid zone and from adjacent regions. We used linear regression to test for associations between marsh characteristics and the distribution of pure and admixed sparrows. We found a positive correlation between genotype and environmental variables with a patchy distribution of genotypes and habitats across the hybrid zone. Ecological niche models suggest that the hybrid niche was more similar to that of A. nelsoni and habitat suitability was influenced strongly by distance from coastline. Our results support a mosaic model of hybrid zone maintenance, suggesting a role for local environmental features in shaping the distribution and frequency of pure species and hybrids across space. 相似文献
17.
This study examined the spatial and temporal variation in fish assemblage composition within two intermittent streams in north‐western Zimbabwe. Eight sites were sampled during three different periods of flow. Twenty‐five species in eight families, dominated by cichlids and cyprinids, were collected. Redundancy analysis (RDA) was used to explore the relationship between species and their environmental correlates. According to variation partition, 68.1% of assemblage variation was explained by both habitat and temporal variables. Most species were associated with large pools, whereas small species were associated with habitats that had gravel and boulders. The temporal aspect suggested a pattern associated with high catch per unit effort (CPUE) for the mormyrids, Clarias gariepinus and Labeo altivelis, during the early rain period. By comparison, the late rain period was associated with high CPUE for Labeo cylindricus, Labeobarbus marequensis, Chiloglanis neumanni and Oreochromis mortimeri, whereas the rest of the species had high CPUE during both the late rain and dry periods. The assemblage composition was more diverse during the late rain period. Refuge availability during the dry period appeared to be essential for the assemblage of the intermittent streams. Protection of these temporal habitats is therefore important in conserving fish assemblages within intermittent streams of the Lake Kariba area. 相似文献
18.
Elanor Miller Chris Lalas Steve Dawson Hiltrun Ratz Elisabeth Slooten 《Marine Mammal Science》2013,29(4):606-628
Stomach contents of 63 Hector's dolphins (Cephalorhynchus hectori) were collected between 1984 and 2006 from throughout New Zealand to provide the first quantitative assessment of prey composition. Twenty‐nine taxa were identified. Those most commonly consumed were red cod (Pseudophycis bachus), ahuru (Auchenoceros punctatus), arrow squid (Nototodarus sp.), sprat (Sprattus sp.), sole (Peltorhamphus sp.), and stargazer (Crapatalus sp.). By mass, these six species contributed 77% of total diet. Red cod contributed the most in terms of mass (37%), while ahuru and Hector's lanternfish (Lampanyctodes hectoris) were consumed in large numbers. Prey ranged from <1 cm to >60 cm in total length, but the majority of prey items were <10 cm long, indicating that for some species, juveniles were targeted. Diets of dolphins from South Island east and west coasts were significantly different, due largely to javelinfish (Lepidorhynchus denticulatus) being of greater importance in west coast stomachs, and a greater consumption of demersal prey species in the east. The feeding ecology of Hector's dolphin is broadly similar to that of other Cephalorhynchus species. Hector's dolphin is shown to feed on species from throughout the water column, and differences in diet between populations are thought to reflect prey availability. 相似文献
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20.
Meadow J. Kouffeld Michael A. Larson R. J. Gutiérrez 《The Journal of wildlife management》2013,77(6):1192-1201