scholarly journals Intensive use of an intertidal mudflat by foraging adult American horseshoe crabs Limulus polyphemus in the Great Bay estuary, New Hampshire

2010 ◽  
Vol 56 (5) ◽  
pp. 611-617 ◽  
Author(s):  
Wan-Jean Lee
Keyword(s):  
New England ◽  
Breeding Season ◽  
Foraging Ecology ◽  
Seasonal Pattern ◽  
High Tide ◽  
Limulus Polyphemus ◽  
Survey Method ◽  
Intertidal Mudflat ◽  
Activity Levels ◽  
Intensive Use

Abstract Although concerns about harvesting levels of the American Horseshoe Crab, Limulus polyphemus have prompted increased research into its ecology, current understanding of the species’ foraging ecology is mostly limited to mid-Atlantic populations. This study elucidates the spatial and temporal pattern of Limulus foraging on an intertidal mudflat of a northern New England estuary. A novel survey method was used to monitor Limulus foraging activity without disturbing the sediment. A fixed 50 m×2 m transect was monitored with monthly surveys of the number of Limulus feeding pits from June to October 2009, May and June 2010. Snorkelling surveys were also carried out to observe individual behavior and examine the spatial scale of activity of individual animals. Results showed frequent and intensive use of the mudflat by foraging Limulus. Limulus were actively foraging within the survey area during all months surveyed. Foraging patterns exhibited a seasonal pattern with activity levels peaking in August 2009 and increased significantly towards the end of the study in June 2010. It was also shown that Limulus intertidal foraging persisted and peaked after the spring breeding season. Observations of foraging Limulus revealed that individual predators dig multiple pits within a single high tide, with little disturbance to the sediment in between. In addition to altering the perception of Limulus as a subtidal predator outside of the breeding season, findings from this study suggests a segregation of spawning and feeding habitats, thus underscoring the need to consider a wider range of critical habitats in the management of Limulus populations.

scholarly journals Myxomatosis in farmland rabbit populations in England and Wales

1989 ◽  
Vol 103 (2) ◽  
pp. 333-357 ◽  
Author(s):  
J. Ross ◽  
A. M. Tittensor ◽  
A. P. Fox ◽  
M. F. Sanders
Keyword(s):  
Breeding Season ◽  
Annual Cycle ◽  
Seasonal Pattern ◽  
Mortality Factor ◽  
Mass Movements ◽  
Wild Rabbit ◽  
Regulatory Effect ◽  
Methods Of Calculation ◽  
Attenuated Virus ◽  
Virus Strains

SUMMARYThe overall pattern and consequences of myxomatosis in wild rabbit populations were studied at three farmland sites in lowland southern England and upland central Wales between 1971 and 1978. When results from all years were combined, the disease showed a clear two-peaked annual cycle, with a main autumn peak between August and January, and a subsidiary spring peak during February to April.Rabbit fleas, the main vectors of myxomatosis in Britain, were present on full-grown rabbits in sufficient numbers for transmission to occur throughout the year, but the observed seasonal pattern of the disease appeared to be influenced by seasonal mass movements of these fleas. However other factors were also important including the timing and success of the main rabbit breeding season, the proportion of rabbits which had recovered from the disease and the timing and extent of autumn rabbit mortality from other causes.Significantly more males than females, and more adults and immatures than juveniles, were observed to be infected by myxomatosis. Only 25–27% of the total populations were seen to be infected during outbreaks. Using two independent methods of calculation, it was estimated that between 47 and 69% of infected rabbits died from the disease (much lower than the expected 90–95% for fully susceptible rabbits with the partly attenuated virus strains that predominated). Thus it was estimated that 12–19% of the total rabbit populations were known to have died directly or indirectly from myxomatosis.Although the effects of myxomatosis were much less than during the 1950s and 1960s, it continued to be an important mortality factor. It may still have a regulatory effect on rabbit numbers, with autumn/winter peaks of disease reducing the numbers of rabbits present at the start of the breeding season.

scholarly journals Foraging ecology and choice of feeding habitat in the New Zealand Fairy Tern Sternula nereis davisae

2013 ◽  
Vol 24 (1) ◽  
pp. 72-87 ◽  
Author(s):  
STEFANIE M. H. ISMAR ◽  
TOM TRNSKI ◽  
TONY BEAUCHAMP ◽  
SARAH J. BURY ◽  
DAVID WILSON ◽  
...  
Keyword(s):  
New Zealand ◽  
Stable Isotope ◽  
Breeding Season ◽  
Foraging Ecology ◽  
Avicennia Marina ◽  
Breeding Population ◽  
Breeding Bird ◽  
Breeding Sites ◽  
Sand Spit ◽  
Feeding Habitat

SummaryNo published information is available on the foraging ecology and choice of feeding habitat of New Zealand’s rarest breeding bird: the New Zealand Fairy Tern (NZFT) Sternula nereis davisae. To address this gap, we conducted an assessment of the largest remaining breeding population at Mangawhai Harbour, Northland, New Zealand, during the chick-rearing period of the 2010/2011 breeding season. We combined visual tracking of birds with prey surveys and stable isotope analyses, and we present the first quantitative assessment of NZFT foraging. We recorded 405 foraging dives that show NZFT foraging habitat includes the water edges, shallow channels, and pools on the tidal flats of mangrove-lined (Avicennia marina var. resinifera) parts of the estuary; tidal pools on mud- and sandflats in the mid-estuary and lower harbour; the shallow margins of the dredged main channel in the lower harbour; the oxbow lagoons on the sand spit; and coastal shallows. Our study identifies the mangrove-lined highly tidal and shallow mid-estuary and the lagoon on the sand spit as foraging hotspots for the Mangawhai breeding population of the NZFT. The prey survey employed a seine-net sampling method at identified NZFT foraging sites and yielded 4,367 prey-sized fish of 11 species, two of which had not previously been reported in Mangawhai Harbour, as well as numerous shrimps. The most abundant fish were gobies of the genus Favonigobius. Our stable isotope results highlight gobies as the most important prey for NZFT chick rearing, also indicating that flounder Rhombosolea sp. contribute to NZFT diet. We raise the possibility that shrimps may also constitute a substantial diet component for NZFT, potentially providing up to 21% of diet mass for adult birds. While our results provide a first basis to understanding the feeding ecology of NZFT during their breeding season in order to facilitate conservation planning, further research is required to address inter-annual variation and to identify key foraging grounds for this Critically Endangered bird at other breeding sites.

scholarly journals Macrozoobenthos Community Structure and its Relationship with Waters Quality of Kampung Baru, Sebong Lagoi Village, Bintan Regency

2021 ◽  
Vol 5 (1) ◽  
pp. 20-28
Author(s):  
Wahyu Muzammil ◽  
Nova Prihatin ◽  
Winny Retna Melani
Keyword(s):  
Water Quality ◽  
Diversity Index ◽  
Sampling Site ◽  
High Tide ◽  
Quality Standards ◽  
Survey Method ◽  
Ecological Index ◽  
Index Value ◽  
The Relationship

Kampung Baru is an area on Bintan Island which is located in Sebong Lagoi Village, Teluk Sebong District, Bintan Regency, Riau Islands Province. This study aimed at determine the structure of the macrozoobenthos community, the condition of the physico-chemical parameters of the waters and the relationship between macrozoobenthos and water quality. This research was conducted using a survey method. Sampling site points of this study using random sampling method with 30 sampling site points at high and low tide. The parameters measured are physical, chemical and biological parameters of the water. The results showed that there were 18 species of macrozoobenthos consisting of 4 classes of macrozoobenthos and 3 phylum at 30 sampling site points, namely mollusca, annelida, and arthhopoda phylum. Based on the ecological index value, it is known that the macrozoobenthos species in Kampung Baru waters are still classified as low with disproportionate conditions. The values ​​of diversity index (low), uniformity index (high) and dominance index (low). Water quality of Kampung Baru waters at high tide still meet quality standards of Kepmen-LH No. 51 of 2004, but at low tide the values ​​of temperature, DO, and salinity parameters did not meet quality standards. The relationship between macrozoobenthos parameters and water quality using PCA analysis where density parameters have a relationship with two parameters, namely temperature and pH.

scholarly journals Characterising the foraging ecology and mercury exposure of the Nationally Critical Whenua Hou diving petrel

2021 ◽  
Author(s):  
Grace Tocker
Keyword(s):  
Breeding Season ◽  
Trophic Level ◽  
Interannual Variation ◽  
Prey Species ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Mercury Exposure ◽  
Potential Threat ◽  
Breeding Seasons ◽  
Diving Petrel

<p>With seabird species in decline globally, significant research has gone into characterising their key prey species and foraging areas that need protection. Knowledge on the diet of a species has important implications for the development of conservation programmes. The sand dune system on Whenua Hou is home to the endemic Whenua Hou diving petrel (Pelecanoides whenuahouensis; hereafter WHDP) and a population of common diving petrels (Pelecanoides urinatrix; hereafter CDP). The WHDP is considered ‘Nationally Critical’ due to its small population size (~200 individuals) and restricted breeding range (0.018 km2) on Whenua Hou. The foraging ecology of the WHDP is relatively unknown, as is its exposure to sources of marine pollution. This thesis aimed to characterise the foraging ecology of the WHDP, the potential interspecific competition with the sympatric CDPs, the prey present in the diets of each species, and their resulting exposure to mercury from the environment. In chapter 2, I used stable isotope analysis to infer the trophic dynamics of the WHDP. By sampling and analysing both blood and feathers, I was able to investigate potential differences in WHDP foraging ecology between the breeding and non-breeding seasons. I found a difference between the foraging ecology of male and female WHDPs, with results indicating females forage further out to sea than males and on prey of lower trophic value. I found that WHDPs forage an entire trophic level higher during the breeding season than the non-breeding season. As my sampling effort spanned three consecutive breeding seasons (2017-2019), I was able to detect interannual variation in the foraging ecology of WHDPs. The results revealed that WHDPs foraged at a higher trophic level during the breeding season of 2018 compared to that of 2017 or 2019. By characterising the isotopic niches of both the WHDPs and CDPs over the three years, I was able to demonstrate a degree of trophic segregation between the two species during the breeding season. In chapter 3, I designed and went through the initial development stages for a novel multiplex-PCR assay to identify the prey species present in the diets of WHDPs and CDPs. The obstacles faced in the development of this protocol highlighted the suitability of DNA metabarcoding as an alternative method. In chapter 4, I analysed the mercury concentration in the same blood and feather samples used for stable isotope analysis. I demonstrated that male WHDPs had higher concentrations of mercury in their tissues than females, correlating with their foraging at a higher trophic level. The interannual variation in mercury concentration did not correlate with the trophic variation of WHDPs among years, indicating that the environmental fluctuations in mercury levels had a stronger effect on mercury exposure than diet. WHDP tissues consistently had higher concentrations of mercury than CDPs, correlating with their isotopic niche segregation and highlighting a potential threat to individual survival and reproductive success in WHDPs. Overall, my results describe patterns in the foraging ecology of the WHDP, as well as highlighting the potential threat from mercury exposure. This research can be used as a baseline for future investigations into the key prey species for the endangered WHDP and the impacts mercury exposure may be having on the population growth of this species. </p>

Endogenous opioids and the control of seasonal LH secretion in Soay rams

1985 ◽  
Vol 107 (3) ◽  
pp. 341-353 ◽  
Author(s):  
F. J. P. Ebling ◽  
G. A. Lincoln
Keyword(s):  
Breeding Season ◽  
Chronic Treatment ◽  
Seasonal Pattern ◽  
Pulse Frequency ◽  
Suppressive Effect ◽  
Endogenous Opioids ◽  
Endogenous Opioid ◽  
Acute Increase ◽  
Lh Releasing Hormone ◽  
Lh Secretion

ABSTRACT Soay rams were treated with naloxone and/or morphine at different stages of their annual reproductive cycle to study the role of endogenous opioid peptides in the control of pulsatile LH secretion. The responses in intact rams were compared with those shown by pinealectomized (PNX) or superior cervical ganglionectomized (SCGX) rams which had a different annual testicular cycle. Naloxone (4–6 mg/kg i.v.) given to intact rams at four times of the year induced significant increases in LH pulse frequency in the breeding season in September and December, but minimal responses in the non-breeding season in June. Similar treatments given to PNX or SCGX rams induced good responses in March, June and September and the poorest response in December; the different seasonal pattern between the intact and PNX/SCGX rams was correlated with differences in the timing of their testicular cycles. Morphine (1 mg/kg i.v.) induced a significant decrease in LH pulse frequency when given to intact rams in October, but no significant effects were observed when morphine was given to sexually inactive rams in early July. Naloxone (1 mg/kg i.v.) given concurrently with morphine in October reversed the suppressive effect and resulted in an actual increase in LH pulse frequency above pretreatment levels. Morphine-treated rams showed normal LH responses to injections of LH-releasing hormone (LHRH) indicating that the site of opiate inhibition was on hypothalamic LHRH secretion rather than on pituitary LH release. Chronic treatment of intact and PNX rams with naloxone 1 mg/kg every 4 h for 7 days) in April and October produced the expected acute increase in LH pulse frequency in the intact rams in October, and at both times of year in the PNX rams, however there was no sustained increase in LH secretion in response to chronic naloxone in any of the treatment groups. The response to the second naloxone injection was much reduced and was absent after 3 days; responsiveness to naloxone was restored within 2 days of stopping the chronic treatment. The overall results indicate that an endogenous opioid mechanism is involved in the tonic inhibition of LH secretion and that this mechanism is most active in the breeding season when both naloxone and morphine have marked effects on pulsatile release of LH. Regulation of endogenous opioids in the hypothalamus may be part of the mechanism by which environmental factors modulate steroid negative-feedback control of LHRH and thus LH secretion in seasonally breeding mammals. J. Endocr. (1985) 107, 341–353

scholarly journals Dangerous dining: surface foraging of North Atlantic right whales increases risk of vessel collisions

2011 ◽  
Vol 8 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Susan E. Parks ◽  
Joseph D. Warren ◽  
Karen Stamieszkin ◽  
Charles A. Mayo ◽  
David Wiley
Keyword(s):  
New England ◽  
North Atlantic ◽  
Foraging Ecology ◽  
Early Spring ◽  
Cape Cod ◽  
Late Winter ◽  
Right Whale ◽  
Suction Cup ◽  
Right Whales ◽  
North Atlantic Right Whales

North Atlantic right whales are critically endangered and, despite international protection from whaling, significant numbers die from collisions with ships. Large groups of right whales migrate to the coastal waters of New England during the late winter and early spring to feed in an area with large numbers of vessels. North Atlantic right whales have the largest per capita record of vessel strikes of any large whale population in the world. Right whale feeding behaviour in Cape Cod Bay (CCB) probably contributes to risk of collisions with ships. In this study, feeding right whales tagged with archival suction cup tags spent the majority of their time just below the water's surface where they cannot be seen but are shallow enough to be vulnerable to ship strike. Habitat surveys show that large patches of right whale prey are common in the upper 5 m of the water column in CCB during spring. These results indicate that the typical spring-time foraging ecology of right whales may contribute to their high level of mortality from vessel collisions. The results of this study suggest that remote acoustic detection of prey aggregations may be a useful supplement to the management and conservation of right whales.

Seasonal population dynamics of chewing lice (Phthiraptera: Amblycera and Ischnocera) infesting three species of woodpeckers (Aves: Piciformes: Picidae) in Manitoba, Canada

2016 ◽  
Vol 148 (6) ◽  
pp. 683-692 ◽  
Author(s):  
Robert J. Lamb ◽  
Terry D. Galloway
Keyword(s):  
Breeding Season ◽  
Seasonal Pattern ◽  
Seasonal Patterns ◽  
Chewing Lice ◽  
Northern Flicker ◽  
Picoides Pubescens ◽  
Colaptes Auratus ◽  
Male To Female ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

AbstractThree species of woodpeckers (Piciformes: Picidae) in Manitoba, Canada, were examined for chewing lice (Phthiraptera): the resident downy woodpecker (Picoides pubescens(Linnaeus),n=55), and two migrants, yellow-bellied sapsucker (Sphyrapicus varius(Linnaeus),n=316) and northern flicker (Colaptes auratus(Linnaeus),n=225). Six species were collected:Menacanthus pici(Denny) (Amblycera: Menoponidae) from all hosts, and five species of Ischnocera (Philopteridae):Penenirmus auritus(Scopoli) from downy woodpeckers and sapsuckers,Picicola snodgrassi(Kellogg) andBrueelia straminea(Denny) from downy woodpeckers, andPenenirmus jungens(Kellogg) andPicicola porismaDalgleish from flickers. Adults and nymphs were present on downy woodpeckers all year, and on migrant sapsuckers and flickers from when they arrived until they left, suggesting lice reproduce continuously on their hosts. Prevalence and mean intensities of louse infestations generally decreased from their respective springtime levels to their lowest values during or at the end of the breeding season of their hosts, and then increased in various degrees during the fall. No seasonal pattern in louse sex ratios was observed except on northern flickers, where male to female ratios for two of three species were lowest during the breeding season. Resident and migrant hosts had similar seasonal patterns of infestation by lice.

Foraging ecology and time budgets of non-breeding shorebirds in coastal Cuba

2014 ◽  
Vol 30 (4) ◽  
pp. 347-357 ◽  
Author(s):  
Erica Nol ◽  
Kate MacCulloch ◽  
Lisa Pollock ◽  
Laura McKinnon
Keyword(s):  
Breeding Season ◽  
Foraging Ecology ◽  
Niche Partitioning ◽  
Time Budgets ◽  
Factors Affecting ◽  
Breeding Grounds ◽  
Main Determinants ◽  
Species Specific ◽  
Average Body ◽  
Foraging Time

Abstract:During the non-breeding season, shorebirds, a large and important group of wetland vertebrates, divide their time between foraging, resting and maintenance activities. We examined factors affecting time budgets, foraging techniques and rates, and spacing patterns of 14 to 92 individuals each of 10 shorebird species spending the non-breeding season in Cayo Guillermo, Cuba. We hypothesized that all species would spend the majority of their time foraging. Time spent foraging ranged from 20–85% of total time and was significantly negatively related to average body size. Apparent aggression (e.g. chasing or being chased) occurred in < 10% of individuals in all species and was not related to maximum counts of conspecifics. Aggression was most common in the black-necked stilt but did not vary in frequency as a function of activity. Vigilance varied in occurrence from 0–53% of individuals, but the frequency was not related to maximum counts. Intraspecific distances were generally greater between foraging than non-foraging birds. For most species interspecific distances were similar to intraspecific distances during foraging but greater than intraspecific differences during non-foraging, suggesting some overlap in foraging habitat and niche partitioning during non-foraging. Shorebirds that used primarily tactile techniques foraged closer together than primarily visual foragers. Low rates of aggression, as an index of potential competition, suggest that species-specific energy requirements rather than competitive interactions are the main determinants of foraging behaviour on these tropical non-breeding grounds.

Effects of temperature on the development and abundance of the sheep blowfly Lucilia sericata (Diptera: Calliphoridae)

1992 ◽  
Vol 82 (1) ◽  
pp. 125-131 ◽  
Author(s):  
R. Wall ◽  
N. French ◽  
K.L. Morgan
Keyword(s):  
Life Cycle ◽  
Ambient Temperature ◽  
Simulation Model ◽  
Temperature Effects ◽  
Seasonal Pattern ◽  
Lucilia Sericata ◽  
Activity Levels ◽  
Life Cycle Stages ◽  
Simple Simulation ◽  
Effects Of Temperature

AbstractThe effects of ambient temperature on all component life cycle stages of the sheep blowfly Lucilia sericata Meigen were examined under controlled conditions. The critical base temperatures and the number of day-degrees required for completion of each stage were determined. Using these data a simple simulation model was developed to evaluate temperature effects on the seasonal pattern of L. sericata abundance. The number of flies estimated by the model to be available for capture, together with the temperature over each capture period determining adult activity levels, were able to account for 77% of the variance in L. sericata abundance observed over a season.

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