Breeding density of Dippers Cinclus cinclus' Grey Wagtails Motacilla cinerea and Common Sandpipers Actitis hypoleucos in relation to the acidity of streams in south-west Scotland

The distribution of breeding pairs of Dippers Cinclus cinclus , Grey Wagtails Motacilla cinerea and Common Sandpipers Actitis hypoleucos was assessed along 18 streams in south-west Scotland during summer 1987, and the lengths of territories, occupied by 5 5 breeding pairs of Dippers, were measured. In each stream the water chemistry, physical structure (e.g. gradient, altitude, nature of bankside vegetation) and density of aquatic invertebrates was determined. The density of breeding pairs of dippers was significantly lower along streams of low pH (high acidity) and steep gradients, and territories were significantly longer at these sites compared with those of higher pH. Many of the invertebrate families that are important prey for Dippers were scarce at sites of low pH, particularly caddisfly larvae (Trichoptera) and mayfly nymphs (Ephemeroptera). The low numbers and large territories of breeding pairs of Dippers on acidic streams may be due to reduced density and diversity of macroinvertebrate prey. Stream pH was not an important correlate of the distribution or density of Grey Wagtails or Common Sandpipers. It is suggested that the lack of any similar effect of pH on these other two species compared with Dippers is attributable to differences in their feeding ecology.     

Aspects of the breeding biology of Dippers Cinclus cinclus in the southern catchment of the River Wye,Wales

Laying dates, clutch and brood size, and the incidence of double brooding, in Dippers breeding in the southern catchment of the Welsh River Wye between 1978 and 1983 are described and compared with data from other regions of Britain and mainland Europe. The mean size of 222 clutches (4.78±0.08) was found to be significantly larger than values given by all other studies in Britain where data were sufficient for statistical comparison. This is discussed in relation to territory quality and other influences.     

Calculating census efficiency for river birds: a case study with the White-throated Dipper Cinclus cinclus in the Pyrénées

Using the binomial law we modelled field data to estimate the probability ( ̂ ) of detecting pairs of breeding White-throated Dippers, and the population size ( ̂ ± confidence limits). The model was divided into two parts according to whether the actual size of the population under study was known or not; in the latter case the truncated binomial model was used. Dipper abundance data were collected from three 4-km-long river tracts in the Pyrénées (France) during the breeding seasons of different years. Goodness-of-fit tests indicated that the binomial model fitted the data well. For a given visit during the survey, the estimated probability of detecting any pair of Dippers if they were present was always high (0.63–0.94) and constant from year to year but not between sites. Estimations ( ̂ ) of the size of the population provided by the binomial model were very close to that derived from mapping techniques. This study provides the first ever quantification of the number of visits required to detect birds on linear territories: three visits were necessary to detect the whole breeding population.     

Assessing the impact of extreme flooding on survival in a southern European population of White-throated Dippers Cinclus cinclus

Capsule: There were only weak effects of winter flooding episodes on apparent annual survival of a White-throated Dipper breeding population in northern Iberia.

Aims: To test whether extreme winter flooding episodes affected survival in a breeding population of White-throated Dippers Cinclus cinclus.

Methods: Dippers were ringed during the breeding seasons of seven consecutive years on rivers in northern Iberia. Cormack–Jolly–Seber models were used to estimate apparent annual survival in relation to flooding during the winter periods.

Results: We obtained weak evidence for an effect of flooding during the winter on the surveyed population. Two of the six winters were characterized by having an exceptionally high discharge. Our models showed that survival in the subsequent breeding period tended to be lower, although models assuming constant survival were equally well supported.

Conclusion: Extreme flooding in winter may affect survival of some White-throated Dippers in northern Iberia, but its impact at the population level seems to be weak.     

The diet of breeding Dippers Cinclus cinclus and their nestlings in the catchment of the River Wye, mid-Wales: a preliminary study by faecal analysis

A preliminary study by faecal analysis into the diet of seven pairs of breeding Dippers and their nestlings was undertaken in the catchment of the River Wye in spring 1983. Macro-invertebrate items in faeces could be identified to family and quantified on the basis of mouthparts whilst the macro-invertebrate prey available to each pair of Dippers was assessed quantitatively by riffle-sampling.
In terms of numerical abundance, ephemeropteran nymphs, particularly Baetidae, and trichopteran larvae, particularly Hydropsychidae, were more important to adults and nestlings, respectively. When prey weights were taken into account, trichopteran larvae were the most important macro-invertebrate group to both, but especially to nestlings.
Some macro-invertebrate groups were selected in proportion to their abundance in the environment although indices of electivity indicated that prey selection for adults and nestlings, respectively, was negatively and positively correlated with prey weight. Significant changes in diet were also apparent with nestling age: smaller items, such as ephemeropteran nymphs, were eaten by younger nestlings whilst larger items, such as trichopteran larvae, became more frequent up to Day 15 after hatching.     

Winter territoriality and its implications for the breeding ecology of White-throated Dippers Cinclus cinclus

Capsule: Pairs of White-throated Dippers Cinclus cinclus which defended winter territories bred earlier than non-territorial individuals, but there was no difference in reproductive success.

Aims: The effect of winter territoriality on breeding ecology has rarely been studied in resident birds. We carried out a preliminary investigation of whether winter territorial behaviour and territory size affect the timing of reproduction, breeding territory size and reproductive success in a riverine bird, the White-throated Dipper.

Methods: We monitored an individually marked population of White-throated Dippers in the UK. Wintering individuals were classified as either territorial or ‘floaters’ according to their patterns of occurrence and behaviour, and their nesting attempts were closely monitored in the subsequent months. Winter and breeding territory sizes were measured by gently ‘pushing’ birds along the river and recording the point at which they turned back.

Results: All birds defending winter territories did so in pairs, but some individuals changed partners before breeding. Territorial pairs that were together throughout the study laid eggs significantly earlier than pairs containing floaters and those comprising territorial birds that changed partners. However, there were no significant differences in clutch size, nestling mass or the number of chicks fledged. There was no relationship between winter territory length and lay date or any measure of reproductive success, although sample sizes were small. Winter territories were found to be significantly shorter than breeding territories.

Conclusion: Winter territoriality may be advantageous because breeding earlier increases the likelihood that pairs will raise a second brood, but further study is needed. Territories are shorter in winter as altitudinal migrants from upland streams increase population density on rivers, but this may also reflect seasonal changes in nutritional and energetic demands.     

Energetics of the annual cycle of Dippers Cinclus cinclus

Time-activity budgets and energy expenditure of Dippers Cinclus cinclus were studied in all months of the year and for every stage of the annual cycle. The commonest daytime activity was feeding (54%), then resting (43%) and flying (4%). On a 24-hr day basis the most marked changes in activity followed from changing daylengths. DEE (Daily Energy Expenditure), derived from time-activity budgets through the year and laboratory estimates of metabolism, averaged 201 kj d ^-1 in females and 228 kj d ^-1 in the larger males. Over a more restricted range of circumstances, direct estimates of DEE obtained from 77 Dippers using the doubly labelled water technique averaged 205 ± 43 kj d^-1 and 251 ± 55 kj d^-1 in females and males, respectively. Overall, the correspondence between these largely independent estimates of energy expenditure was reasonably close. DEE was highest during breeding (laying-females; rearing-males) and in late winter for both sexes. The lowest energy expenditures occurred during moult, amongst juveniles and in early winter. Incubating females and mate-guarding males also had low energy costs. Across all stages of the annual cycle body size, activity patterns, ambient temperature and river flow had significant effects on energy expenditure. The rate at which food was gathered to meet these changing energy demands varied widely. While some of this variation was imposed by a seasonal environment, it was also likely to reflect adaptive shifts in rates of food gathering, in some cases consequent upon the changing fitness benefits of various non-feeding activities.     

The adaptive significance of brood size and time of breeding in the dipper Cinclus cinclus (Aves: Passeriformes) as seen from post-fledging survival

We assessed the post-fledging survival of dippers Cinclus cinclus from 743 broods in relation to brood size, time of hatching and territory quality. We paid particular attention to assessing whether contrasting breeding performance along unproductive (i.e. acidic) and productive (i.e. circumneutral) rivers represented strategies which optimized the number of surviving young.
For all brood sizes, post-fledging survival varied significantly through the breeding season, with most survivors coming from attempts in the peak period of hatching. After correcting for these seasonal effects, the most common brood size overall, of four, was also the most productive as seen from post-fledging survival; differences in the frequency of occurrence and survival between broods of four and five were marginal. Moreover, a change in the modal brood size from five to four occurred as the season progressed. consistent with a shift in brood productivity.
Broods at acidic sites were significantly smaller than at circumneutral sites; while brood size four was the most productive at both types of site, brood size three was the second most productive at acidic sites, while brood size five was the second most productive at circumneutral sites. Dippers at acidic sites bred significantly later than at circumneutral sites, but post-fledging survival declined most rapidly through the season at the former.
These survival data provide evidence from both seasonal and spatial patterns that brood sizes in the dipper may be optimized in ways consistent with the enhancement of productivity. By contrast, delayed breeding at acidic sites contrasted with the patterns expected from optimization, instead reflecting resource scarcity.     

Diet of Dippers Cinclus cinclus during an early winter spate and the possible implications for Dipper populations subjected to climate change

The prey composition of the diet of Dippers Cinclus cinclus was shown to differ between baseflow and spate conditions. In southwest Ireland, faecal pellets were collected during a heavy spate in early winter 1991 and during a period of baseflow conditions three weeks later. The diet composition differed significantly between the two periods. During baseflow conditions diet was dominated by trichopteran larvae, especially Limnephilidae, whereas during the spate period diet was composed primarily of ephemeropteran nymphs, particularly Baetidae, and dipteran larvae of the family Simuliidae. Diet during the spate period also contained greater proportions of prey taxa of terrestrial origin. Enhanced hydrological cycles with greater precipitation, predicted under current climate change models, may have an effect on the diet of Dippers and this is discussed.     

Time-activity budgets and energetics of Dipper Cinclus cinclus are dictated by temporal variability of river flow.

The white-throated Dipper (Cinclus cinclus) is unique among passerine birds by its reliance on diving to achieve energy gain in fast-flowing waters. Consequently, it should have evolved behavioural adaptations allowing responding directly to runoff patterns (one of the assumptions of the Natural Flow Regime Paradigm-NRFP). In this study (October 1998-August 2001), we investigated how behavioural and energy use strategies in Dippers might vary under the natural flow regime of snowmelt-dominated streams in The Pyrénées (France) where natural flow regime is highly seasonal and predictable. We recorded time spent in each of 5 behavioural activities of ringed birds to estimate time-activity budgets and derive time-energy budgets enabling the modelling of daily energy expenditure (DEE). Annual pattern in 'foraging' and 'resting' matched perfectly the annual pattern of the natural regime flow and there was a subtle relationship between water stage and time spent 'diving' the later increasing with rising discharge up to a point where it fell back. Thus, time-activity budgets meet the main prediction of the NRFP. For males and females Dippers, estimates of feeding rates (ratio E(obs)/E(req)=observed rate of energy gain/required foraging rate) and energy stress (M=DEE/Basal Metabolic Rate) also partly matched the NFRP. Maximum value for the ratio E(obs)/E(req) was registered in May whilst M peaked in spring. These ratios indicated that Pyrenean Dippers could face high energy stress during winter but paradoxically none during high snowmelt spates when food is expected to be difficult to obtain in the channel and when individual birds were observed spending ca 75% of the day 'resting'. Annual pattern in DEE did not match the NFRP; two phases were clearly identified, the first between January to June (with oscillating values 240-280 kJ d(-1) ind(-1)) and the second between July and December (200-220 kJ d(-1) ind(-1)). As total energy expenditure was higher during the most constraining season or life cycle, we suggest that energy management by Dippers in Pyrenean mountain streams may fit the 'peak total demand' hypothesis. At this step of the study, it is not possible to tell whether Dippers use an 'energy-minimisation' or an 'energy-maximisation' strategy.     

Impact of extreme flooding on the annual survival of a riparian predator,the Brown Dipper Cinclus pallasii

The predicted effects of global climate change include altered patterns of precipitation and more extreme weather events, leading to an increase in the severity and frequency of episodic disturbances such as floods. These changes may affect lotic prey communities, which could indirectly affect aquatic and riparian predators through trophic linkages. We assessed whether extreme flooding affected the apparent survival of Brown Dippers Cinclus pallasii in Taiwan using mark–resighting data and climate data. The probability of survival was negatively correlated with the degree of flooding, and survival of first‐year birds was lower than that of adults. Previous analyses of this system suggest that the main, indirect mechanism driving such patterns is the impact of flood disturbance on the aquatic invertebrate prey of Brown Dippers. Our results show that changes in prey communities induced by flooding have the potential to affect predators in aquatic and adjacent riparian habitats. This highlights the importance of considering cross‐ecosystem linkages when identifying conservation and management goals in the face of future climate uncertainty.     

Niche segregation of Himalayan river birds

ABSTRACT.   The Himalayan Mountains have more specialist river birds than anywhere on earth, but factors permitting their coexistence have not been evaluated. We examined potential ecological segregation of five sympatric insectivores based on diet, morphology, and foraging behavior during the breeding and nonbreeding seasons in central Nepal. Little Forktails ( Enicurus scouleri ) and Brown Dippers ( Cinclus pallasii ) were highly aquatic in habitat use and diet (89–96% of prey of aquatic origin), but took prey that differed in size and composition. Spotted Forktails ( E. maculatus ) foraged primarily along channel margins, and took more aquatic than terrestrial prey (59% vs. 40%). White-capped ( Chaimorrornis leucocephalus ) and Plumbeous ( Rhyacornis fuliginosus ) water redstarts took primarily terrestrial or aerial prey by gleaning marginal surfaces and flycatching over channels. Two species were similar morphologically (Little Forktail and Plumbeous Water Redstart), but had different diets. Our results illustrate clear ecological separation among this guild of co-occurring river birds on one or more niche dimensions that we suggest is mediated by the physical complexity of mountain, riverine habitats.     

Conservation genetics of American Dipper (<Emphasis Type="Italic">Cinclus mexicanus</Emphasis>): the genetic status of a population in severe decline

American Dippers (Cinclus mexicanus) were once known to occur in streams throughout the Black Hills of South Dakota and Wyoming, but now dippers number about 50–75 individuals and reside almost exclusively in a single stream. The recent decline of the American Dipper in the Black Hills of South Dakota is thought to be due to local stream degradation. As a result of the decline of C. mexicanus in the Black Hills of South Dakota and Wyoming, the Black Hills population of American Dippers is a candidate for designation as a distinct population segement (DPS) and might warrant protection and special management. One criterion for DPS designation is genetic uniqueness. Here we present the results of a genetic assessment of the Black Hills population of C. mexicanus. Data presented here indicate that the dipper population in the Black Hills is genetically distinct from other sampled populations. Further population sampling will be needed to understand the genetic population structure of C. mexicanus throughout its range. Furthermore, the recent decline in the Black Hills dipper population should be a warning that other populations (and other species) may be experiencing similar declines and that such montane habitats are worthy of special management.     

Time-activity budgets and energetics of Dipper Cinclus cinclus are dictated by temporal variability of river flow

The white-throated Dipper (Cinclus cinclus) is unique among passerine birds by its reliance on diving to achieve energy gain in fast-flowing waters. Consequently, it should have evolved behavioural adaptations allowing responding directly to runoff patterns (one of the assumptions of the Natural Flow Regime Paradigm—NRFP). In this study (October 1998–August 2001), we investigated how behavioural and energy use strategies in Dippers might vary under the natural flow regime of snowmelt-dominated streams in The Pyrénées (France) where natural flow regime is highly seasonal and predictable. We recorded time spent in each of 5 behavioural activities of ringed birds to estimate time–activity budgets and derive time–energy budgets enabling the modelling of daily energy expenditure (DEE). Annual pattern in ‘foraging’ and ‘resting’ matched perfectly the annual pattern of the natural regime flow and there was a subtle relationship between water stage and time spent ‘diving’ the later increasing with rising discharge up to a point where it fell back. Thus, time–activity budgets meet the main prediction of the NRFP. For males and females Dippers, estimates of feeding rates (ratio E_obs/E_req = observed rate of energy gain / required foraging rate) and energy stress (M = DEE / Basal Metabolic Rate) also partly matched the NFRP. Maximum value for the ratio E_obs/E_req was registered in May whilst M peaked in spring. These ratios indicated that Pyrenean Dippers could face high energy stress during winter but paradoxically none during high snowmelt spates when food is expected to be difficult to obtain in the channel and when individual birds were observed spending ca 75% of the day ‘resting’. Annual pattern in DEE did not match the NFRP ; two phases were clearly identified, the first between January to June (with oscillating values 240–280 kJ d^− 1 ind^− 1) and the second between July and December (200–220 kJ d^− 1 ind^− 1). As total energy expenditure was higher during the most constraining season or life cycle, we suggest that energy management by Dippers in Pyrenean mountain streams may fit the ‘peak total demand’ hypothesis. At this step of the study, it is not possible to tell whether Dippers use an ‘energy-minimisation’ or an ‘energy-maximisation' strategy.     

Prevalence of haematozoan parasites in the White-throated Dipper Cinclus cinclus in southern Europe

Capsule White-throated Dippers from southern Europe were found to be infected by three haemosporidians.

Aims To examine the occurrence of blood parasites in dippers in the Iberian Peninsula and to investigate the relationship between prevalence levels, environmental factors and bird fitness.

Methods White-throated Dippers were trapped with mist-nets from five montane areas in the centre of the Iberian Peninsula. Parasites were detected from blood samples by polymerase chain reaction screening.

Results About half (51.3%) of 152 dippers showed some kind of infection. The genus Haemoproteus was recorded in 49.3% of the birds, and the genus Leucocytozoon in 19.1%, while Plasmodium was present only in 0.7%. Among the infected birds, 34.6% carried a double infection (Haemoproteus?+?Leucocytozoon). Prevalence did not differ between gender or age-classes, but it varied between study sites, being significantly higher in mountains with higher precipitation. There was a reduction in body mass owing to double infection in yearling males only.

Conclusion This is the first work assessing parasite prevalence in dippers from southern Europe. Infection of dippers by haemosporidians is likely to be related to a study site's climatic envelope.     

Relationships between stream habitat and breeding territory length of the Brown Dipper (Cinclus pallasii) in Taiwan

Dippers from the genus Cinclus are highly specialised predators on aquatic invertebrates, and occupy linear territories along rivers where measurements of variations in quality are relatively straightforward. For these reasons, they are ideal model species in which to examine factors affecting territory size. In this paper, we investigated the influence of stream habitats on the territory length of the Brown Dipper (Cinclus pallasii) in Taiwan. The biomass of aquatic insects and other stream habitat variables were analyzed to determine their relationships with the territory length of Brown Dippers from November 1988 to May 1989. Compared with slow-moving waters, riffle areas contained significantly greater insect biomass (paired t test, t ₁₁ = 3.49, P < 0.01), of which trichopteran larvae contributed about 70%. Dippers spent more time foraging in riffles than in slow-moving waters. In addition, dippers preferred foraging in shallow riffles, but avoided deep, slow-moving waters (G = 62.53, df = 3, P < 0.001). Territory length (1,045 ± 165 m [SE], n = 14) was negatively related to proportion of riffles (r ² = 0.5715, P < 0.01), total aquatic insect biomass (r ² = 0.5840, P < 0.01), and altitude (r ² = 0.7176, P < 0.001). In factor analysis, four factors were extracted from the 14 stream variables. However, only factor 1 was significantly related to territory length (r ² = 0.5207, P < 0.01). Factor 1 explained 42.8% of the total variance and collectively revealed the importance of high food abundance. In other words, Brown Dipper territories were the shortest along high-altitude streams with abundant riffles, fewer pools and abundant aquatic insects. These results indicate that abundant supply of accessible invertebrate prey is the most important factor affecting the territory length of Brown Dippers. This is consistent with Cinclus species elsewhere, and reveals the importance of clean, productive river ecosystems.     

湖南辣椒地方品种资源与湘研辣椒品种选育的灰色关联分析

本文用灰色关联方法分析了40份湖南辣椒地方品种资源和12个杂交组合.结果表明,辣椒果实干物质、Vc和辣椒素含量、TMV、CMV和炭疽病抗性与第一花节位、株高、株幅、分枝数等植株性状的关系较近,与果长、果宽、单果重量、结果数和单株产量等果实性状的关系较远.根据灰色关联度的大小,从湖南辣椒地方品种资源中筛选出重要育种材料有伏地尖、河西牛角椒和湘潭晚辣椒,从杂交组合中筛选出优良杂交品种湘研1号、湘研3号、湘研5号、湘研9号和湘研10号,这些材料和品种均在育种和生产中发挥了重要作用,说明灰色关联分析方法能够用于指导辣椒育种.     

Influences of status and recent breeding experience on the moult strategy of the yellow-nosed albatross Diomedea chlororhynchos

The primary moult of individually colour-ringed, adult yellow-nosed albatrosses at nests on Gough Island was examined in 1983 and related to the status of each bird and its breeding history in the previous year. Adults renew only about half of their primaries each winter and suspend moult while breeding. Birds that bred successfully renewed fewer primaries than did unsuccessful birds or nonbreeders. There were no differences in primary moult between the sexes or in relation to size. Yellow-nosed albatrosses show complex wave moult as an adaptation to slow renewal of flight feathers. The energy, nutrient or time requirements for feather renewal may conflict with breeding annually so that there is a trade-off between the extent of moult desirable to maintain flight efficiency and the benefits of breeding in successive seasons.     

Hematological health state indices predict local survival in a small passerine bird, the great tit (Parus major)

In birds, it has been shown that reproductive effort may impair parental condition, while the relation of different condition indices to subsequent survival is still poorly understood. In this study, we measured body mass and various hematological condition indices in breeding great tits in relation to local survival. Number and quality of nestlings and the occurrence of second broods, potentially reflecting parents' breeding effort, were also considered in analyses. The great tits, both male and female, that returned the following year had had a higher albumin/globulin ratio, lower plasma globulin concentration, and a lower heterophile/lymphocyte ratio during breeding in the preceding year, compared to those who did not return. Surviving males (but not females) also had had a higher level of circulating lymphocytes, compared to nonsurvivors. There was no correlation between breeding effort and survival. We conclude that better immunological state and lower stress in great tits during breeding were positively related to their survival probability.     

The evolution of breeding strategies in the flightless cormorant (Nannopterum harrisi) of the Galapagos

The evolution of breeding strategies in male and female flightless cormorants is thought to have been shaped by three principal factors: Firstly, an unpredictable food supply; secondly, a prolonged breeding season; and thirdly, the inbred nature of colonies.
These factors have selected for opportunistic breeding and for females (but not males) to attempt to raise two broods per season by deserting their offspring to the further care of their mates, while they re-breed with new males. That this strategy maximizes the inclusive fitness of both sexes is examined in terms of genetic pay-off and the relative food-providing efficiency of male and female parents. Parental investment is examined in relation to female desertion. Mate selection is discussed and some theoretical aspects of breeding strategy evolution are considered.