Breeding performance of kestrels at Eskdalemuir, south Scotland

The performance of 144 pairs of European kestrels breeding in upland young conifer plantations was studied from 1976 to 1979. Laying started between 15 April and 1 June, and was 14 days later, on average, in the poor vole year of 1977 than in the other years. Some 38% of pairs failed to fledge young, mainly because they deserted clutches during incubation. The proportion of pairs that failed was positively correlated with total rainfall in May, but apparently not with estimated spring vole numbers. There was a marked seasonal decline in both clutch size and the probability of breeding successfully, so that early laying pairs fledged 2.7 times as many young per attempt as did late pairs. Within years, there was considerable variation in the laying date between pairs. On the available data, environmental factors, such as the habitat or vole numbers around the nest, appeared to have less influence on this variation than did the age of the pair members, their pairing date or their previous breeding experience.     

滇西南稻区白背飞虱种群特征及其关键影响因子

为明确滇西南沧源县稻区白背飞虱Sogatella furcifera的种群发生特征及其影响因子,于2010-2019年通过灯诱监测和田间调查的方法,分析沧源县白背飞虱的越冬种群、灯诱种群及田间种群发生特征,并对白背飞虱种群数量的影响因素进行相关性分析.结果表明:(1)白背飞虱以成、若虫在再生稻、落粒稻上越冬,越冬虫量最...     

NUMBERS OF MEADOW PIPITS ANTHUS PRATENSIS ON MOUNTAIN FARM GRASSLAND IN NORTH WALES IN THE BREEDING SEASON

On c. 15 ha of mountain farm grassland in Wales, during 1972-75, adult Meadow Pipits were present during March–September (but scarce in August–September). Breeding occurred during late April to late July. Incubation was performed by the female but both sexes fed the nestlings. Adults showed an average annual mortality of 54%. Adults spent nearly all their time on the ground, but varied in their activities and use of the habitat according to the stage of breeding. Their unobtrusive behaviour had a marked effect on the ease with which they could be observed for a population count. Males were seen on 30% of the days for which they were assumed to be present and were recorded giving song-displays on 28% of the days when they were actually seen. We conclude that, to count all the birds present on a site, most must be marked, sightings must be carefully mapped and the number of observer days must be at least 20, preferably in April-May. The numbers of individually marked (and a few unmarked) birds were determined by mapping them on large-scale aerial photographs. This gave an average annual density of 48 resident pairs per km². The average home range was 2.18 ha; this value remained relatively constant from year to year. At low population density individual home ranges were separated from one another, and there was some unoccupied ground, but at high population density the ranges overlapped with one another.     

Seasonal movements of British Greenfinches Carduelis chloris

Ringing recoveries are used to investigate the seasonal movements of British Greenfinches. Significantly more females than males make such movements. Outward movement begins by early November and continues until at least late January. The return movement can last from January to May and is particularly rapid in March and early April. The directions of the outward movements are widely dispersed but show trends towards the south and, except in western areas, towards the west. In Britain south of latitude 54°N the proportion of birds leaving their breeding grounds in winter increases from west to east, being negligible in the south-west and largest in East Anglia, but relatively small near the south coast. Distances moved show a similar dependence. The numbers making seasonal movements in a given year are correlated with the breeding population, particularly in south-east England.     

The influence of planting date,transgenic Bt maize and hybrid relative maturity on European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) ovipositional patterns

A three year study was carried out at Hoytville and at Wooster, Ohio, USA from 2006 to 2008 to investigate the influence of planting date, transgenic maize and hybrid maturity on Ostrinia nubilalis (Hubner) population dynamics and oviposition patterns. Maize plants were planted in late April or early May, mid‐May and early June during each year. The moth flight pattern showed bivoltine generations during the three years. The first moth flight peaked in June, with the populations declining during July. The second moth flight peaked in August and declined towards the end of September or early October. Egg mass density did not differ significantly between transgenic and non‐transgenic maize of different maturities. Significant differences were observed, however, among planting dates, sampling dates, and sampling date × planting date interactions. Generally higher numbers of egg masses from second generation moths were deposited on late planted maize than middle and early plantings.     

Ecological studies on Oligochaeta inhabiting depositing substrata in the Irwell, a polluted English river

SUMMARY. Oligochaete worms dominate the macroinvertebrate fauna of the River Irwell, in north west England. The river is polluted by domestic and industrial wastes. Tubificids constituted 86.8% of the worm fauna, with three dominant species; Tubifex tubifex (Müller), representing 43.1% of the total oligochaetes, Limnodrilus hoffmeisteri Claparède, representing 26.8% and Limnodrilus udekcmianus Claparède, representing 16.7%. The Naididae were the next most abundant worms, representing 6.1% of the oligochaete fauna, with Nais elinguis Müller comprising 5.0%.
T. tubifex and L. hoffmeisteri were abundant along the length of the river, but reached their greatest numbers in the organically polluted lower reaches at Agecroft and Salford. The density of L. udekemianus was low in the Irwell above the entry point of the heavily polluted River Roch, but high below this point. N. elinguis was abundant above the Roch entry point and scarce below it.
In the three dominant tubificids, the main population recruitment occurred during the summer months (April to September for T. tubifex , May to November for L. hoffmeisteri and June to October for L. udekemianus ). In N. elinguis , there was massive recruitment in April.     

The relationship of spring and summer weather with density and breeding performance of the Buzzard Buteo buteo, Goshawk Accipiter gentilis and Kestrel Falco tinnunculus

The density of territorial pairs, laying pairs and the breeding performance of three raptor species, Buzzard Buteo buteo , Goshawk Accipiter gentilis and Kestrel Falco tinnunculus , were investigated in relation to rainfall and temperature during the breeding cycle. In all species the density of territorial pairs was not related to spring rainfall and temperature. In the Buzzard the percentage of pairs that bred unsuccessfully was significantly related to May rainfall. The number of young fledged was negatively correlated with rainfall in April and May. In the Goshawk the percentage of laying pairs was negatively correlated to rainfall in March and April. Success in terms of number of young fledged was related mostly to May temperature. In the Kestrel the density of territorial pairs was dependent on March-April rainfall. The number of young fledged per successful pair was highly correlated with May and June temperature. All these relationships showed that the hatching period and the subsequent two weeks were most important for chick survival.     

广东吴川红火蚁消长规律

采用系统调查的方法研究广东吴川红火蚁Solenopsis invicta Buren蚁巢数量、蚁丘体积和工蚁的年度变化规律,结果表明1年之中红火蚁活动蚁巢密度出现2个高峰期,分别在6~8月和10~12月;4~7月和10~11月新增活动蚁巢数量较大;蚁巢自然消亡出现在多个时间,其中以9月最多。4~11月红火蚁工蚁活动旺盛,用诱饵诱集法监测,5、6月和10、11月红火蚁工蚁出现2个明显盛期,而陷阱法中工蚁数量为单峰型,高峰出现在7月。2种监测方法获得的工蚁数量间相关系数为0.88,达到极显著相关。气温、地表温度、5cm土壤温度与2种方法获得的工蚁数量间相关系数分别为0.88,0.88,0.86和0.93,0.94,0.95,均达极显著水平。红火蚁蚁丘体积4~6月、9~12月增大幅度较大,其中6月份蚁巢增长最为明显。     

布氏田鼠种群繁殖特征研究

越冬田鼠每年可繁殖3胎,第1胎幼仔生于4月下旬到6月上旬,第2胎幼仔生于5月中旬到7月上旬,第3胎幼仔生于6月中旬到7月下旬。种群上升年份(1987)各胎幼仔出生高峰比1988年的提前10天左右。1987年越冬鼠第1胎集中,如4月下半月,1987年怀孕率为100%,而1988年只有44.44%。6月上半月以前越冬鼠为种群繁殖的主体,而后被当年生鼠所取代。从4月下半月到9月上半月共出生4批同龄群。K₁和K₂组生长发育旺盛,当年就参加种群繁殖,可怀孕1—3胎。K₃组生长发育较慢,当年并不性成熟,越冬后性成熟成为种群越冬鼠的主体。K₄出生晚,数量少,很少能度过漫长寒冷的冬季而成为种群的无用或潜在的繁殖力量。本文还发现越冬鼠的平均胎仔数显著高于当年鼠：种群上升年份越冬鼠平均胎仔数高于种群下降年份,而当年生鼠的平均胎仔数年度间则没有显著性差异。     

内蒙古荒漠草原亚洲小车蝗的种群动态

2010—2011年于内蒙古乌兰察布市四子王旗格根塔拉草原对亚洲小车蝗Oedaleus asiaticus(B.-Bienko)种群动态进行了研究。结果表明,亚洲小车蝗种群空间格局为随机分布;亚洲小车蝗于6月中旬开始孵化出土,1～3龄蝗蝻高峰期在6月中下旬至7月初,终见期在7月下旬;4～5龄蝗蝻于6月下旬始见,高峰期在7月上中旬,终见期在7月末;成虫于7月上旬始见,高峰期在7月中旬至8月下旬,终见期在9月上旬。应用最优分割法将亚洲小车蝗种群动态划分为3个阶段:(1)6月中旬,为蝗蝻开始出土期,数量稀少,空间格局为聚集分布或随机分布;(2)6月下旬至7月上中旬,为蝗蝻发生盛期,密度低时为随机分布,密度高时为聚集分布;(3)7月中下旬至9月上旬,为成虫发生期,空间格局为随机分布。     

Population dynamics of the gastropod Theodoxus jordani (Sowerby) in the Shatt Al-Arab river

SUMMARY. 1. Measurements of the population density of Theodoxus jordani were made for the period July 1980 until June 1981. Numbers showed a well-defined pattern of fluctuation and varied between 390 in February and 1804 snails m⁻² in May after recruitment.
2. The population age structure revealed that the snail was semelparous, and that one generation dominated the population for most of the year.
3. The breeding season was long. Snails laid eggs from early December to the end of April. Eggs were laid in protective capsules and one snail developed per capsule. Total population natality estimated from field samples was 9813 snails m⁻².
4. Age specific mortality was high immediately after recruitment, low during the juvenile stages, and increased sharply at the adult stage with the onset of reproduction.     

杭州郊区菜蚜种群的数量消长规律

对杭州郊区菜蚜的数量消长规律进行了连续多年的系统调查 .结果表明 ,在杭州郊区十字花科蔬菜上发生的菜蚜只有桃蚜 (Myzuspersicae)和萝卜蚜 (Lipaphiserysimi) .2种菜蚜混生种群的数量消长 1年中有 2个明显的高峰 ,分别出现在 5～ 6月和 1 1月前后 ;一般年份高峰期田间虫量可达平均每株 50 0头以上 ,且第 2个高峰虫量较高 ,持续时间较长 .在夏末秋初气温明显偏低的年份 ,8～ 9月作物上虫量上升迅速 ,最高也可达平均每株上千头的水平 .盛夏和隆冬季节数量都很低 .每年的 1 2月至次年的 5月以桃蚜占绝对优势 ,7～ 1 0月以萝卜蚜占绝对优势 ,而 5～ 7月和 1 0～ 1 2月则 2种蚜虫的发生比例交错变换 .温度是决定菜蚜混生种群数量消长规律和导致 2种蚜虫季节消长规律差异的一个主要因子 .文中对食料、天敌等因子的作用也做了讨论 .     

Population structure and dynamics of wood mouse Apodemus sylvaticus in Iceland

Five-year-studies of two wood mouse populations (Apodemus sylvaticus L.) were carried out outside the village Vík. S. Iceland, and in a birch forest close to the lake Mývatn, N. Iceland. The population at Vík was studied on a 1.10 ha grid on a slope covered with Angelica archangelica L., the seeds of which constituted a major food resource for the mice. Altogether 948 individuals were caught, marked and followed during 1973–1978. No other free-living small mammals occur in Iceland, and predator pressure is low and considered non-existent on the Angelica slope. The population density was extremely high; highest autumn density recorded was 150 ind ha^?1. Like other Apodemus populations, the one at Vík showed a typical seasonal pattern in numbers: a winter decrease, relatively stable numbers in late summer, and an autumn peak. Breeding started in late April or early May and ended in late September; no winter breeding was observed. Three or four litters were produced, and the last litter(s) of the season greatly contributed to the autumn increase. The output of young per reproductive female throughout the year was negatively correlated with spring density, and autumn peak density with the number of females in August. Also overwinter success and weight changes appeared to be associated with population density (and weather). Survival rates did not vary much between years and seasons and were consistently rather high. Autumn survival of juveniles was positively correlated with mean minimum temperatures. Juvenile survival was, at least at times, negatively affected by the presence of adult males. Trapping outside the main grid did not indicate any marked dispersal, though some immigration to the grid must have occurred, especially in spring and early summer. Among the factors governing the population density and dynamics of wood mouse at Vík we emphasize the absence of interspecific competition and predation, the rich and dependable food resources (mainly Angelica seeds), the mild (though moist and windy) climate, the shelter of dense Angelica stands, the abundance of crevices (e.g. nest-sites), and the social interactions. The birch forest in northern Iceland was low productive and the wood mouse population differed from the Vík population by exhibiting low density, short breeding season, and high vagility; characteristics we consider to be representative for most Apodemus populations in Iceland.     

Community composition, seasonal dynamics and interspecific correlation of waterbirds in the Qiantangjiang River estuary and Hangzhou Bay

Waterbird surveys were conducted regularly in the Qiantangjiang River estuary and Hangzhou Bay from July 2007 to November 2011. A total of 128 species (nine orders and 18 families) were recorded, including 119 migrants which accounted for 93% of the total species; eleven species were listed as National Protected Species. Inter-specific correlation analysis for 13 shorebird populations and nine duck populations recorded over time found that 21 pairs of shorebirds and 23 pairs of ducks were correlated. By looking at seasonal dynamics and migration patterns we were able to divide the migration process into six stages: (1) late July to late September was the migration peak of shorebirds, which were dominated by Limosa limosa, Calidris ruficollis and Charadrius mongolus. (2) Early October to mid-December was the migration peak of wintering migrants of shorebirds and ducks, which were the first two large groups in our study areas. (3) Late December to mid-February was the wintering period of migration waterbirds. (4) Late February to late March was the peak migration of ducks and the winter migrants of shorebirds dominated by Calidris alpina. (5) Early April to mid-May was the migration peak of passage migrants such as, Calidris ruficollis, Calidris acuminate and Limosa limosa but the population size of shorebird winter migrants dominated by Calidris alpine was still larger than the former. (6) Late May to mid-July was the breeding season of all egrets, summer migrants of gulls and several species of shorebirds. Our surveys show that interaction among species is possibly an important determinant of community composition of shorebirds and wintering ducks during the migration season. It may be the geographical position and community composition of migrant shorebirds across Hangzhou Bay that mean during the northward migration there are far more shorebirds than during the southward migration.     

Responses of breeding duck populations to changes in food supply

We describe the main results of a monitoring study at Lake Myvatn, northern Iceland, begun in 1975. The aims were to find factors that limit production of young and cause changes in density of breeding ducks of several species. We estimated numbers of ducks in spring, before nesting, numbers of ducklings produced, and numbers moulting. Chironomid and simuliid dipterans were monitored with window traps. In all duck species studied, production of young was correlated with food abundance. Reproductive performance determined subsequent changes in spring population density of Eurasian Wigeon, Tufted Duck, Greater Scaup, Common Scoter and Harlequin Duck. The spring population of Barrow's Goldeneye apparently did not respond to variation in reproductive success. Moulting numbers of male Tufted Duck were related to chironomid abundance, but not those of Scaup and Barrow's Goldeneye. Moulting numbers were not associated with previous reproductive output.     

Seasonal dynamics of the tick Haemaphysalis tibetensis in the Tibetan Plateau,China

The tick Haemaphysalis tibetensis (Acari: Ixodidae) Hoogstraal is an important arthropod vector widespread in the Qinghai‐Tibet Plateau, and knowledge of its seasonal dynamics is still poor. The current study investigated the seasonal dynamics of the parasitic and non‐parasitic H. tibetensis over a 2‐year period from March 2014 to February 2016 in the Tibetan Plateau, China. During this timeframe, non‐parasitic ticks were collected weekly by flag‐dragging in grassland and shrubland areas, and parasitic ticks were removed weekly from selected sheep. Plateau pikas were captured using traps and examined for immature ticks between May to September 2014. Results suggest that non‐parasitic H. tibetensis were mainly distributed in the grassland, and the parasitic adults and nymphs were found mostly on sheep. Larvae were usually found on Plateau pikas and the prevalence of infestation and mean parasitic intensity were 72.1 and 1.81%, respectively. Adults were observed from March to July with the major peak occurring in mid‐April. Nymphs were found from March to August and reached a peak in late June. Larvae were collected from April to September, and their numbers peaked in late May. In the parasitic and non‐parasitic period, the overall sex ratio of males to females was 1.62 and 1.30, respectively. Results show that H. tibetensis can complete one generation per year, with a population overlap between stages over the spring‐summer months. These findings provide additional information on the biology and ecology of H. tibetensis as well as insights on its control in the environment and on sheep.     

Density-dependent regulation of breeding success in the Red-crested Pochard Netta rufina

Capsule: Numbers of breeding Red-crested Pochard Netta rufina in the Czech Republic were positively correlated with reproductive success in the previous year, yet annual productivity, declined with increasing numbers of females at the beginning of the breeding season, suggesting local limiting factors on this population.

Aims: To test the hypothesis that long-term increases in numbers of a breeding population of Red-crested Pochard Netta rufina can be explained by the productivity (numbers of ducklings fledged) in the previous year. We also test for the potential adverse effect of population size on population productivity in the current year.

Methods: Data from 2004 to 2016 from South Bohemia, Czech Republic, were analysed using TRends and Indices for Monitoring Data software to investigate changes in numbers of adults, numbers of females at the start of the breeding season and number of broods produced.

Results: There was a significant increase in the numbers of adults and females at the beginning of each breeding season. Numbers of adults in May positively correlated with productivity (numbers of ducklings fledged) in the previous breeding season, but relative productivity (broods per adult female) in the current year was negatively correlated with females abundance at the beginning of the breeding season.

Conclusions: The study identifies density-dependent regulation as a factor in the population productivity of Red-crested Pochards using intensively managed fishponds as a breeding ground.     

Life cycle and population dynamics of Annina mesopotamica (Ahmed), (Isopoda, Flabellifera) in the Shatt Al-Arab Region, Basrah, Iraq

A population of the intertidal, ovoviviparous, cirolanid isopod Annina mesopotamica was studied at the Al-Chibassy tributary of the Shatt Al-Arab river from 14 May 1973 to 29 April 1974, and at the Garmat-Ali river of the Shatt Al-Arab, Basrah, Iraq from 5 November 1984 to 30 June 1986. Population density varied between 128 to 5760 individuals m^–2 with a mean of 1218 m^–2. Highest numbers occurred between June and September. Breeding extended for most of the year except November/January to February/March, although ovigerous females were present throughout the year. The incubation period varied with season, and was ca. 2 weeks during the warmest period, and about a month at lower temperatures. Egg numbers varied between 4 to 66 with mean 24. Brood size was linearly proportional to female size. The size frequency distribution of the population was polymodal with a predominance of females over males. Four different types of growth curves were found: exponential, concave, convex, and intermediate between concave and convex. Growth rate varied between 0.63 and 2.19 mm month^–1. Mortality was higher among summer cohorts. Life span varied between 5 and 11 months.     

Relationship between breeding activity and rainfall for Swainson's Spurfowl,Pternistis swainsonii,within southern Africa,with specific reference to the Springbok Flats,Limpopo Province,South Africa

We collated the literature available on the breeding activity of the Swainson's Spurfowl Pternistis swainsonii and made use of reliable unpublished reports, nest record cards and field observations within the Springbok Flats, Limpopo Province, South Africa to establish breeding seasons and pairing behaviour. The onset of breeding (egg laying) is closely associated with rainfall, with male gonad development, population density and covey size (pairing behaviour), all correlated with rainfall. Peak breeding activity is from January–April in South Africa, February–May in Zimbabwe and March–June in Botswana. Egg laying has been recorded in all months and sporadic egg laying in the winter months is most likely the result of isolated rainfall. Mean clutch size is 5.2 eggs/hen (n = 140) with an incubation period of 23 days and brood hatching success and chick survival of 69.4% over the southern African sub-region. Current hunting seasons within Limpopo Province are in line with the recommended hunting season for this region and should remain unchanged: 15 June–30 September. The success of this phasianid can be attributed to its extended breeding season, high survival rate of hatchlings and the potential of birds to breed within their first year.     

Breeding population size and trends of American Oystercatchers on small islands of Bahía Santa María‐La Reforma,Sinaloa, Mexico

The islands of Bahía Santa María‐La Reforma, Sinaloa, Mexico, host the largest breeding population of the western race of American Oystercatchers (Haematopus palliatus frazari). This resident shorebird has a small breeding range restricted to northwestern Mexico and, although listed as endangered, little is known about their breeding biology. We estimated the number of pairs on the El Rancho and Melendres islands, the detection rate of pairs in different habitats, and the relationship between habitat length and number of pairs during three breeding seasons (2016–2018). In 2016 and 2017, the number of pairs peaked in mid‐April (97 and 95 pairs, respectively) at El Rancho, and in early May and early April (50 and 42 pairs, respectively) at Melendres. In 2018, both islands had the maximum number of pairs during mid‐May, with 109 pairs at El Rancho and 42 at Melendres. Detectability of breeding pairs in plots with sandy beach and dune habitats was higher (86–100%) than in those with mangrove habitat (22%). Detectability was associated with habitat type and should be considered in estimating the population size of this subspecies. We estimated that ~ 11% of the total frazari American Oystercatcher population breeds on these two small islands. The density of breeding pairs varied between habitats (range = 0–13 pairs/km). We also found a positive relationship between the number of pairs and plot length, suggesting that habitat availability might be a limiting factor for populations of American Oystercatchers in Mexico.