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.

Hepatitis a virus: Growth characteristics of in vivo and in vitro propagated wild and attenuated virus strains

1984 ◽  
Vol 14 (4) ◽  
pp. 373-386 ◽  
Author(s):  
Daniel W. Bradley ◽  
Charles A. Schable ◽  
Karen A. McCaustland ◽  
E. H. Cook ◽  
Bert L. Murphy ◽  
...  
Keyword(s):  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Growth Characteristics ◽  
Virus Growth ◽  
Attenuated Virus ◽  
Virus Strains

Reproduction of the Rabbit, Oryctolagus cunniculus (L.), on Macquarie Island, Subantarctic

1978 ◽  
Vol 5 (3) ◽  
pp. 317 ◽  
Author(s):  
IJ Skira
Keyword(s):  
Breeding Season ◽  
Annual Cycle ◽  
First Year ◽  
Corpora Lutea ◽  
Macquarie Island ◽  
Pregnant Females

The reproduction of rabbits on Macquarie I. was studied from December 1973 to February 1975. The breeding season extended from late August 1974 to mid-March 1975; both sexes showed an annual cycle in development and regression of the gonads. Between mid-October and mid-November 92% of females sampled were pregnant; during this period the maximum numbers of corpora lutea and embryos were 8.55 and 6.50 per female respectively. Few resorptions occurred although the number of pregnant females that resorbed increased as the breeding season progressed. Of all rabbit kittens produced in the 1974-75 breeding season, 64% were born by mid-December 1974. Female rabbits in their first year of breeding bore the greatest number of kittens; natality decreased as females aged.

Planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China: annual cycle

2010 ◽  
Vol 91 (1) ◽  
pp. 97-105 ◽  
Author(s):  
Yong Jiang ◽  
Henglong Xu ◽  
Khaled A.S. Al-Rasheid ◽  
Alan Warren ◽  
Xiaozhong Hu ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Yellow Sea ◽  
Seasonal Pattern ◽  
Jiaozhou Bay ◽  
Temporal Distribution ◽  
Northern China ◽  
Ciliate Abundance ◽  
Ciliate Species ◽  
Enclosed Bay ◽  
Planktonic Ciliate

To reveal the annual patterns of planktonic ciliate communities, planktonic ciliate species composition, abundance and biomass, and responses to environmental conditions, were investigated during an annual cycle in Jiaozhou Bay, Qingdao, northern China. A total of 64 species belonging to five orders (Oligotrichida, Haptorida, Cyrtophorida, Hypotrichida and Tintinnida) were identified, 9 of which were dominant. Ciliate communities presented a clear seasonal pattern in terms of both abundance and biomass. A single peak of ciliate abundance and biomass occurred in late August, mainly due to the oligotrichids, tintinnids and haptorids. The 9 dominant species showed a distinct temporal distribution with seasonal successions of ciliate communities. Multivariate analyses revealed that ciliate abundance was significantly correlated with water temperature, dissolved oxygen and nutrients, especially nitrate nitrogen and soluble reactive phosphate (P < 0.05). These findings provided basic data on annual cycle of planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China.

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.

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

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.

scholarly journals Changes in the virulence of myxoma virus strains in Britain

1987 ◽  
Vol 98 (1) ◽  
pp. 113-117 ◽  
Author(s):  
J. Ross ◽  
M. F. Sanders
Keyword(s):  
Myxoma Virus ◽  
Wild Rabbit ◽  
National Surveys ◽  
Testing Method ◽  
Development Of Resistance ◽  
Similar Survey ◽  
Virus Strains

SUMMARYNational surveys of the virulence of field strains of myxoma virus were carried out in 1975 (128 virus strains) and in 1981 (123 strains), using the virulence testing method employed in a similar survey in 1962. Results showed that the virulence of field strains had increased between 1962 and 1975, and again between 1975 and 1981. The increases in virulence are thought to be a result of the development of resistance to myxomatosis in wild rabbit populations. The effects of the changes in virulence and resistance are discussed.

POPULATION STRUCTURE AND BODY WEIGHTS OF SNOWSHOE HARES ON MANITOULIN ISLAND, ONTARIO

1964 ◽  
Vol 42 (6) ◽  
pp. 975-986 ◽  
Author(s):  
Robin Newson ◽  
Antoon de Vos
Keyword(s):  
Body Weight ◽  
Population Structure ◽  
Breeding Season ◽  
Age Structure ◽  
Annual Cycle ◽  
Snowshoe Hare ◽  
Adult Females ◽  
Snowshoe Hares ◽  
Body Weights ◽  
Previous Summer

The age structure and body weight of two snowshoe hare populations, just at or passing a cyclical peak in numbers, were studied over 3 years. The survival of the young was poor. Each winter, the young of the previous summer were already too few to replace all the normally expected losses of adults. Numbers therefore decreased from year to year. Shot samples were biased towards adult females in the breeding season. It appeared that they were feeding more heavily than the males as their gut weights at this time were markedly increased. There was a clear annual cycle in body weight with females consistently heavier than males. Immature hares were lighter than adults during their first winter and remained so until they were at least a year old.

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