bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships with undergraduate nursing exchange students – a tutor perspective
Authors: Koskinen Liisa , Tossavainen Kerttu
Published: March 2003

koskinen l. &tossavainen k. (2003) Journal of Advanced Nursing 41(5), 499–508

 Relationships with undergraduate nursing exchange students – a tutor perspective

Background. Student exchange has been used increasingly in nursing education throughout Europe as a method of learning intercultural sensitivity. In the host country, each foreign student is assigned a personal tutor to enhance learning.

Aim. The aim of this study was to describe tutor–student relationships between Finnish nurse teachers and British exchange students from the tutors' perspective.

Ethical issues. The researcher's close relationship with the study context and participants caused some ethical concerns, which will be discussed.

Methods. The data consisted of tutorial session observations, research diary notes, group interviews and background questionnaires. They were analysed using Spradley's developmental research sequence method for ethnographic data.

Findings. The tutoring relationship was pastoral and clinical rather than academic. The pastoral aspect of the relationship was essential in assisting the students to adjust to the stress of studying in a foreign country. On the other hand, tutors were unable to support all the students to overcome their culture shock. Tutors were uncertain about their role and did not integrate Finnish culture or practice into theory, but found their role pleasant.

Conclusions. A dialogic tutor–student relationship is important for learning intercultural sensitivity. Tutoring strategies should be developed to assist students' adjustment to the differences in the host culture and to encourage their reflection on personal, experiential and scientific cultural knowledge during their study abroad.
The response of wild Atlantic salmon parr to acute reductions in water flow
Authors: Armstrong John D. , Braithwaite Victoria A. , Fox Mark
Published: March 2003

1.  A seasonal reduction in water flow, due both to prevailing weather conditions and anthropogenic disturbance, is a prominent feature of the habitat in many riverine systems, yet the response of many aquatic vertebrates, such as juvenile Atlantic salmon, to low flows is not well understood. However, in accordance with general fitness optimization theory, it might be predicted that salmon will emigrate from shallow areas to seek refuge in pools as water levels decrease to critically low levels (fitness approaches zero). To test this prediction, we directly measured the movement response of individual Atlantic salmon (Salmo salar L.) (74–109  mm) to drought in near‐natural mesocosms.

2.  In five separate trials during summer, groups of salmon were introduced into enclosed 30‐m long sections of stream, each comprising a central 10‐m long region of shallow riffle habitat bordered upstream and downstream by 10‐m long regions of deeper water. After fish had settled into home ranges, those fish inhabiting deep areas were removed and the water flow was later decreased to zero over 2 days, so that the riffles were nearly dry. The movements of each individual fish within the enclosures were monitored remotely and continuously using a passive integrated transponder (PIT) tracking system.

3.  Of the total of 33 fish with home ranges that included only riffle habitat, 14 moved into deep water at some point during drought, but only seven of these fish (0–50% between trials) established new home ranges that included deep areas. The others returned to regions of riffle during the drought. None of the eight fish that definitely had not sampled in pool habitat prior to settling on riffle emigrated during drought.

4.  The optimal response of salmon parr to moderate natural drought appears not to be fixed, but for many individual fish it may be to stay in shallow riffle areas. The optimal response of salmon parr to extreme natural drought and anthropogenic de‐watering will, in many cases, be to move. An increase within the population of traits that promote an ideal response to natural drought will therefore make it more vulnerable to severe drought and anthropogenic de‐watering and vice versa.

5.  The absence of emigration by salmon from shallow areas during acute drought can be reconciled with fitness optimization theory if, when natural drought progresses, fish become stranded in shallow areas some considerable time before the point at which they die.
Spatial dynamics of two competing specialist parasitoids in a host metapopulation
Authors: LEI GUANGCHUN , HANSKI ILKKA
Published: March 2003

1.  We investigated spatial dynamics in two specialist larval parasitoids, Cotesia melitaearum and Hyposoter horticola, attacking the Glanville fritillary butterfly, Melitaea cinxia, in Finland.

2.  Presence of C. melitaearum in a host larval group significantly reduced the rate of parasitism by H. horticola (18 vs. 33% in groups with and without C. melitaearum), but there was no significant reverse effect. The parasitism rates at the level of local populations showed a similar trend.

3  Hyposoter horticola females moved frequently among larval groups, whereas C. melitaearum females often spent several days at a single larval group. In agreement with these behavioural observations about movements within populations, H. horticola was found to have a higher colonization rate of host populations than C. melitaearum.

4.  At the within‐population level, C. melitaearum tended to occupy large larval groups in the centre of the host population, whereas H. horticola parasitized also small and more isolated (peripheral) larval groups, especially in the presence of C. melitaearum. At the metapopulation level, host population size had a significant positive effect on the presence of local populations of both parasitoid species, but isolation had a significant negative effect on the presence of C. melitaearum only.

5.  These results suggest that C. melitaearum is a superior competitor, but an inferior disperser to H. horticola, which facilitates the co‐existence of the two species both at the level of local populations and at the level of a metapopulation.

6.  Data from a 50‐patch network showed a decline in the number of host populations from 34 to 13 in 4 years. This decline caused a near‐extinction of the superior competitor, but inferior disperser, C. melitaearum, whereas the abundance of the inferior competitor, but superior disperser, H. horticola, remained relatively constant, in agreement with the prediction of a theoretical model.
Testing the relative influence of instrinsic and extrinsic variation in food availability on feral pig populations in Australia's rangelands
Authors: CHOQUENOT DAVID
Published: March 2003

Instrinsic variation in the availability of food to animal populations reflects the influence of foraging by the animals themselves. Instrinsic variation in food availability provides a link between population density, subsequent food availability and variation in the rate of population increase (r), operating through density‐dependent food shortage. In contrast, extrinsic variation in food availability is caused by environmental influences on food or animal abundance, which are independent of animal foraging. Extrinsic variation in food availability is random relative to that arising through intrinsic shortage. Intrinsic and extrinsic variation in food availability can influence animal populations simultaneously. Intrinsic variation will impart a tendency towards an equilibrium between animal and food abundance. which will be progressively obscured by density‐independent variation as the influence of extrinsic factors increases.

This study used a large‐scale field experiment, in which the density of food‐limited feral pig (Sus Scrofa L.) populations was manipulated on six sites, to assess the relative influence of intrinsic and extrinsic variation in food availability. The experiment evaluated the influence of pig population density on r and the abundance of food resources measured as pasture biomass. It was predicted that if intrinsic shortages dominated variation in food availability, pasture biomass and r would decline with increasing pig density. If extrinsic factors dominated variation in food availability, pig density would have no systematic effect on either pasture biomass or r. If intrinsic and extrinsic sources simultaneously affected variation in food availability, higher pig densities would have no systematic effect on r, but would reduce pasture biomass. The simultaneous model predicts reduced pasture biomass because, in the absence of compensatory changes in other sources of variation, the effects of intrinsic and extrinsic factors will be additive.

To examine further the degree of interdependence in pig and pasture abundance, a series of stochastic models of the grazing system were estimate and the feedback loop comprising the functional and numerical responses of feral pigs to variation in pasture biomass was manipulated.

In the large‐scale experiment, neither pasture biomass nor r declined with increasing pig density, suggesting that food availability was dominated by extrinsic factors. However, limitations of the experiment meant that a minor decline in pasture biomass may have gone undetected. Comparison of simulation models, which included and omitted pasture offtake by pigs, indicated that because they were less efficient grazers and persisted at lower average densities relative to other large herbivores, pigs had little influence on variation in pasture biomass.
Using local–regional richness plots to test for species saturation: pitfalls and potentials
Authors: Srivastava Diane S.
Published: March 2003

1. Plots of local versus regional species richness are an exciting new tool for testing for species saturation in ecological communities. In this method, the local richness of a community is plotted as a function of its regional richness for different biogeographical regions. A proportional relationship between local and regional richness is interpreted as evidence for an unsaturated community, that is, a community with strong evolutionary limits to local richness. There will be no correlation between local and regional richness in a saturated community, that is, a community whose local species richness is limited largely by ecological processes.

2. Although at least 36 data sets have now been analysed using local–regional richness plots, there has not been much critical evaluation of the method. This paper provides such a critique, focusing on the selection of communities for comparison, the prevalence of pseudoreplication and multiple null models, and the effects of differing region size.

3. Local–regional richness plots are best suited for comparing similar habitats between different regions, not different habitats in a single region. In the latter, taxa effects and species pool effects are confounded.

4. Four very different types of local–regional richness plots have been published. Each type of plot has important underlying assumptions which are often not addressed by ecologists.

5. Of the 36 data sets reviewed in this paper, 13 were spatially pseudoreplicated, and 2 were temporally pseudoreplicated. Furthermore, ecologists differ in their choice of null model, with the result that the same local–regional plot could be interpreted as evidence for saturation by one ecologist, and for lack of saturation by another.

6. Differences in region size can result in pseudosaturation, the appearance of saturation by an unsaturated community. A simple model demonstrates this phenomenon. Other sources of error in estimating the regional species pool are also of concern.

7. In conclusion, local–regional richness plots are a potentially useful tool for distinguishing saturated from unsaturated communities, but should be used cautiously, and in conjunction with other supporting evidence (such as the presence or absence of competitive exclusion, resource limitation, density compensation and the effects of species invasions).
Cyclic dynamics in field vole populations and generalist predation
Authors: Lambin Xavier , Petty Steve J. , Mackinnon James L.
Published: March 2003

1. A geographical gradient in the relative impact of generalist and specialist predators on small rodent populations has been hypothesized to be responsible for the gradient in cyclicity found in Fennoscandia. Population oscillations resulting from weasel–vole interactions are said to be dampened by the increasing stabilizing impact of generalist predators in southern Fennoscandia resulting from: (i) a greater abundance and diversity of predators sustained by alternative prey; (ii) the absence of significant snow cover leading to constant exposure of voles to generalist predators; and (iii) a heterogeneous habitat that makes dispersing voles more vulnerable to predators.

2. Changes in the abundance of field voles (Microtus agrestisL.) in a man‐made spruce forest in northern England were recorded during 1984–98 using sign indices at 14–18 sites calibrated with capture–recapture estimates of vole density.

3. Field vole populations exhibited cyclic dynamics which were in many ways similar to those reported from Fennoscandia, including population declines taking place during the breeding season and long periods with no recovery in numbers following population crashes.

4. The density dependence structure of the time series was explored by means of partial autocorrelation functions, which suggested second‐order density dependence. Analyses based on two density estimates per year (spring and autumn) reveal significant negative values for lags of 1, 1·5 and 2 years, suggesting that the time‐lag might be somewhat shorter than 2 years.

5. Estimates of predation on field voles by red foxes and tawny owls at high vole density were above the value predicted for this site and for the whole generalist predator community by a published model assuming that predation by generalist predators stabilizes vole populations. However, empirical estimates of the parameter used both for designing and testing the model are inherently imprecise.

6. A qualitative evaluation of the three variables (see1) correlated to the Fennoscandian gradient and assumed to contribute to variations in generalist predation pressure did not support the hypothesis that low predation rates by generalist predators are necessary for vole dynamics to be dominated by the destabilizing impact of weasel–vole interactions. The specialist/generalist predation hypothesis must therefore be modified to account for the regular population cycles occurring in northern Britain.
Climate change causes contrasting trends in reproductive performance of planktivorous and piscivorous alcids
Authors: Kitaysky Alexander S. , Golubova Elena G.
Published: March 2003

1. Eight years of observations on seabird reproductive success and oceanographic change in Tauyskaya Bay (Okhotsk Sea, north‐western Pacific) were used to evaluate the hypothesis that interannual climate change causes opposite trends in reproductive performances of planktivorous auklets (Aethia cristatella and Cyclorhinchus psittacula) vs. piscivorous puffins (Lunda cirrhata and Fratercula corniculata).

2. The climate change was assessed by examining changes in sea‐surface temperature (SST), time of permanent ice disappearance (ID), wind (WV) and current vectors (CV). Changes in the distribution of zooplankton biomass in the study region were used to assess changes in prey communities. Bird reproductive success was determined as the number of chicks fledged per nest occupied.

3. There were two distinct sets of oceanographic conditions in the study region, as reflected in the SST, ID, WV and CV. Strong northerly winds in the spring produced a late ice disappearance in the study region, whereas easterly winds determined an early ice disappearance. The patterns in ice disappearance were significantly correlated with SST anomalies during the summer. A negative SST anomaly (– 1·2 °C) defined a ‘cold’ regime, whereas a positive SST anomaly ( +  1·2 °C) defined a ‘warm’ regime.

4. Reproductive success of planktivorous auklets was negatively correlated with the SST in the western part of Tauyskaya Bay, whereas reproductive success of piscivorous puffins was positively correlated with the SST. The ‘cold’ season in 1988 was characterized by a strong in‐flow of water masses into the bay area. The ‘warm’ season in 1989 was characterized by well‐mixed warm water inside the bay that were separated from colder water masses outside the bay. Macro‐zooplankton, which were the main prey of planktivorous auklets, were more abundant during the ‘cold’ regime of the ecosystem. Meso‐zooplankton, a potential prey of juvenile pelagic fish, were more abundant during the ‘warm’ regime of the ecosystem.

5. Interannual oceanographic change probably impacts alcid reproductive performances by affecting food accessibility to planktivorous auklets and piscivorous puffins in opposite ways.
Comparative study on the consequences of culling badgers (Meles meles) on biometrics, population dynamics and movement
Authors: Tuyttens F. A. M. , Macdonald D. W. , Rogers L. M. , Cheeseman C. L. , Roddam A. W.
Published: March 2003

1. Capture–mark–recapture data were used to describe the process of recovery from a typical badger removal operation (BRO) at North Nibley, Gloucestershire, UK, which was carried out as part of the government's strategy to control bovine tuberculosis. Data on biometrics, demographics and movement from this low‐density disturbed population were compared with those of two nearby high‐density undisturbed populations (Wytham Woods and Woodchester Park, UK) in order to study fundamental principles of population dynamics and density‐dependence.

2. Badgers moved more between social groups at North Nibley than in the other study areas, particularly in the immediate aftermath of the removal operation.

3. Recolonization of the vacated habitat occurred in the first instance by young females.

4. Although in the first year after the BRO no cubs had been reared in any of the culled groups, and although the shortage of sexually mature boars may have limited the reproductive output of sows in the following year, the population took only 3 years to recover to its (already lowered) preremoval density.

5. Losses from the adult (and cub) population due to mortality or emigration were smaller at North Nibley than at the other sites.

6. There was much evidence that during 1995 and 1996 density‐dependent effects constrained the reproductive output of the high‐density populations, and some support for the hypothesis that badgers exhibit the non‐linear ‘large mammal’ type of functional response to density.

7. Badgers at North Nibley were younger, heavier and in better condition than badgers at Wytham Woods and Woodchester Park.

8. We argue that the disease dynamics are likely to be different in disturbed compared with undisturbed badger populations, and that this could affect the effectiveness of BROs.
The cost of interspecific competition in two gerbil species
Authors: Abramsky Zvika , Rosenzweig Michael L. , Subach Aziz
Published: March 2003

It has been shown that the two common granivorous gerbil species Gerbillus allenbyi and G. pyramidum that coexist in the sand dunes of the Israeli Negev show temporal partitioning in their time of activity. The bigger species, G. pyramidum, aggressively displaces the smaller species from early night‐time. We examined the change in the activity pattern of G. allenbyi in pure and mixed populations in two 1‐ha field enclosures.

We confirmed the temporal pattern reported by Ziv et al. (1993) and Kotler et al. (1993).

We also measured how much energy it takes (in g of millet seeds) to compensate for the costs, associated with interference and exploitation competition, by adding millet seeds to 18 seed trays/enclosure. We added 1, 3, 5, 7 or 9 g of seeds/seed‐tray. In each seed‐tray we mixed the seeds in 2 L of sand.

It took 3–5 g of seeds/seed‐tray (1·8–3 g seeds/day/ha/individual) to completely overcome the competition by G. pyramidum. This is the cost of the interference and exploitation competition from G. pyramidum (in the currency of millet seeds).

The result suggests that there is a trade‐off between interference competition and food to which gerbils respond behaviourally.
A testable linear model for diversity trends in estuaries
Authors: Attrill Martin J.
Published: March 2003

In 1934, Adolf Remane constructed a diagram to describe changes in the number of species along a full salinity gradient within the Baltic. Despite fundamental differences in tidal regimes, the Baltic model has been applied directly to estuaries, becoming subsequently the textbook model for estuarine diversity trends.

 Despite its ubiquity, the Remane diagram has many inconsistent features, making it unsuitable as a quantitative tool for comparing diversity trends between estuaries, including poor definition of x‐axis (salinity), y‐axis (number of species) and variations in sample location (subtidal/intertidal) than can greatly influence the resulting diversity/salinity relationship. Consequently, diversity trends within and between estuaries remain to be tested robustly.

 The major environmental factor influencing the distribution of organisms in estuaries is salinity variation, rather than absolute salinity tolerance as in the Baltic. As salinity range demonstrates a quadratic relationship with mean salinity, an alternative linear model is therefore suggested utilizing mean salinity range at any one point in the estuary (x‐axis) and mean α‐diversity of macroinvertebrates (y‐axis) obtained from subtidal samples to allow comparison with river systems and to minimize salinity variability between interstitial and overlying water.

 The model was tested on an extensive subtidal data set from the Thames estuary (salinity 0–35), significant negative linear relationships between salinity range and α‐diversity being apparent for annual and seasonal data sets. Significant models were also possible for both ‘marine’ and ‘freshwater’ halves of the estuary and for meiofauna α‐diversity.

 The linear model allows formal, statistical investigation of the differences in diversity trends between estuaries and the development of testable hypotheses on aspects of estuarine diversity, including the causes of the species minimum in estuaries. It also has potential as a management tool enabling the definition of sites of concern that fall below their predicted diversity.

 The new model of diversity now requires testing in systems additional to the Thames in order to determine whether this relationship is a macroecological phenomenon or restricted to the test system.
Large‐scale habitat variability, delayed density effects and red deer populations in Norway
Authors: Mysterud Atle , Langvatn Rolf , Yoccoz Nigel G. , Stenseth Nils CHR.
Published: March 2003

Parallel to the large‐scale changes in land‐use patterns over the last century in Europe, many deer species have expanded their range and increased in density, but the role of habitat changes for their population ecology remains poorly documented.

We tested for effects of variability in agricultural (proportion of meadow and density of sheep) and forestry practices (proportion of coniferous and deciduous forest) in 106 municipalities in Norway on body weight of 10 206 female and 15 499 male adult red deer collected over the period 1965–2000.

Long‐term temporal changes in body weights may also be due to delayed density effects, either due to that persistent high density of red deer through grazing and browsing may affect vegetation composition (i.e. an effect of cumulative density after present‐day density is controlled for), or that individuals born at high density start to penetrate the population (cohort‐effects). As these effects may be confounding to variability in forestry or agricultural practice, we also test whether cohort and/or cumulative density may affect body weight of red deer.

There was a strong negative effect of cohort density, but no effect of cumulative density in the previous 10 years once the cohort effect was accounted for.

There was a clear positive effect of proportion of meadow on red deer body weight, while there was no effect of sheep density once the effect of proportion of meadow was adjusted for. Proportion of meadow increased during the study, but most of the variation was between municipalities (i.e. in space).

Neither proportional area of coniferous or deciduous forest consistently affected body weight of red deer in Norway.

Our study emphasizes the multitude of factors over time and space that affects body weight, and hence demography and population dynamics, of large herbivores.
Heterotroph species extinction, abundance and biomass dynamics in an experimentally fragmented microecosystem
Authors: Gonzalez Andrew , Chaneton Enrique J.
Published: March 2003

Species extinction in fragmented habitats is a non‐random process described by transient, rather than equilibrium dynamics. Therefore, ‘static’ approaches focusing on experimentally established spatial gradients of diversity may fail to capture essential aspects of ecosystem responses to species loss.

Here we document temporal changes in microarthropod species abundance, biomass and richness during a community disassembly trajectory following experimental habitat fragmentation of a moss‐based microecosystem.

Habitat fragmentation reduced heterotrophic species richness and community biomass in remnant moss fragments. Extinction was biased towards rare species, and thus occurred initially without significant changes in total community abundance and biomass. Eventual reductions in abundance and biomass were found to lag behind observed declines in species richness.

The presence of moss‐habitat corridors connecting fragments to a large ‘mainland’ area coupled with an immigration rescue effect maintained microarthropod richness, abundance and biomass within remnant fragments.

Our results indicate that both the order of species loss and the dynamics of remnant populations influence the magnitude and timing of ecosystem‐level responses to habitat destruction and isolation.
Larval anurans with synchronous and asynchronous development periods: contrasting responses to water reduction and predator presence
Authors: Lane Simon J. , Mahony Michael J.
Published: March 2003

The larvae of pond breeding frogs experience high rates of mortality, predominantly through predation and pond desiccation. We investigated how the tadpoles of two common species of frog respond to these hazards using factorial experiments conducted in a laboratory.

The eastern brown froglet Crinia signifera
Girard spawns in small, highly ephemeral ponds, while the spotted marsh frog
Limnodynastes tasmaniensis
Günther breeds in more permanent water bodies. Prior to our experiments it was known that
C. signifera
siblings develop quickly and reach metamorphosis comparatively synchronously (
c
. 25–35 days), while
L. tasmaniensis
grow and develop more slowly and time to metamorphosis is highly asynchronous (
c . 60–300 days). It was anticipated that these species would have different strategies for coping with declining water and predators.

A separate experiment was conducted for each species. The factors were Hydroperiod (either constant or gradually declining water volume) and Predator (either the presence or absence of a restrained mosquitofish Gambusia holbrookii
Girard). A random block design was used with six replicates for each possible combination of the factors (
N  = 24). Each replicate consisted of a 13‐l tub of water containing 20 tadpoles. Newly emerged frogs were transferred to one of 24 vivaria. In the arrangement of the vivaria, we maintained the block design of the experiment.

Crinia signifera tadpoles responded to declining water by accelerating development and so reduced time to metamorphosis. However, the resulting metamorphs were smaller and survival rate in the terrestrial stage was significantly lower. This is a clear demonstration of the benefit and cost of phenotypic plasticity in metamorphic traits.

Limnodynastes tasmaniensis tadpoles experiencing declining water were also smaller at metamorphosis, but there was no evidence that they had reduced the time to metamorphosis compared with those in constant water. Moreover the survival rates of the resulting frogs did not differ. Consequently no adaptive plasticity can be inferred.

The data suggest that L. tasmaniensis has a bet‐hedging strategy in which some siblings develop more quickly at the expense of size, while others take much longer but are bigger at metamorphosis as a result.

Tadpoles of both species showed clear behavioural responses to the presence of the predator. They tended to occupy the non‐predator halves of the tubs in replicates where a mosquitofish was present. Neither species altered development rate in the presence of the predator and there was no detectable impact on survivorship in the terrestrial stage.
Connectance in stream food webs
Authors: Schmid‐Araya Jenny M. , Schmid Peter E. , Robertson Anne , Winterbottom Julie , Gjerløv Charlotte , Hildrew Alan G.
Published: March 2003

The properties of food webs are important both in theoretical ecology and environmental management, yet remain elusive. Here, we examined 12 new stream food webs of higher taxonomic resolution and completeness than any previously published data set and combined them with other 10 published stream webs.

Compared with most previously published food webs, these stream communities (containing between 22 and 212 species) had more feeding links per species, a higher fraction of intermediate species (0·78–0·88) and lower fractions of top (0·04–0·09) and ‘basal’ species (0·07–0·15).

The exponent of the log link‐log species relationship (S1·3) differed significantly (ancova: P < 0·001) from the link‐species ‘law’ (S1) and the constant connectance hypothesis (S2). Based on these results, the link scaling law and the constant connectance hypothesis must be rejected for food webs in stream systems.

Connectance was markedly lower than previously reported and decreased with web size. We attribute this to the body‐size disparity of organisms at the top and the bottom of the web, flow disturbance and to the high physical heterogeneity and complexity of the sedimentary habitat. All these may reduce the fraction of possible feeding links that are realized.
Environmental variability, life‐history covariation and cohort effects in the red‐billed choughPyrrhocorax pyrrhocorax
Authors: Reid J. M. , Bignal E. M. , Bignal S. , McCracken D. I. , Monaghan P.
Published: March 2003

The consequences of environmental variability for life‐history evolution are predicted to depend on the pattern of covariation amongst life‐history traits. Using data from a 20‐year study of individually marked red‐billed choughs, we investigate the short‐ and long‐term life‐history consequences of population‐wide variation in reproductive conditions, and demonstrate clear among‐cohort variation and covariation in life‐history parameters.

The mean number of offspring fledging per breeding event varied among years, and was correlated with environmental conditions (temperature and rainfall) during the months preceding breeding. As the variance in breeding performance did not differ among years and choughs did not miss breeding seasons, variation in environmental conditions affected the whole breeding population. Thus the quality of the chough's breeding environment varied amongst years.

Juvenile survival, the probability of recruitment to the breeding population and breeding longevity varied amongst cohorts, and these were positively correlated with the quality of the cohort's natal environment. Offspring fledging under good conditions were more likely to survive to breeding age and recruit, and had longer breeding lives than offspring fledging under poor conditions.

Age at first breeding varied amongst cohorts, and increased with population size at maturity rather than natal conditions.

The total number of offspring that recruits ultimately fledged varied primarily with breeding longevity rather than recruitment age. Thus, the consistent positive covariation amongst life‐history traits meant that the total number of offspring fledged by recruits during their breeding life varied amongst cohorts, and was correlated with the quality of a cohort's natal conditions. Choughs fledging under good conditions themselves ultimately fledged more offspring.

Such environmentally determined variation in offspring fitness is expected to influence optimal patterns of parental investment. We discuss the predictions that environmental variability should select for investment in adult survival and for reduced reproductive effort in poor years.
Which chick is tasty to parasites? The importance of host immunology vs. parasite life history
Authors: Roulin Alexandre , Brinkhof Martin W. G. , Bize Pierre , Richner Heinz , Jungi Thomas W. , Bavoux Christian , Boileau Nicolas , Burneleau Guy
Published: March 2003

The Tasty Chick Hypothesis (TCH) proposes that hatching asynchrony evolved as an antiparasite strategy. Hosts would benefit if ectoparasites aggregate more on the offspring that are of lowest reproductive value within a brood, i.e. on the last‐hatched chicks, because offspring reproductive value generally decreases with hatching rank. The poor body condition of the later‐hatched chicks would impair parasite resistance and render them especially attractive to ectoparasites. Thus, the TCH predicts a decline in chick parasite load with hatching order in avian broods.

We investigated the main assumption of the TCH that junior chicks are less immunocompetent than their senior siblings. We also examine the prediction of the TCH that junior chicks bear more ectoparasites than their senior siblings.

Conform to the assumption of the TCH for hosts, junior chicks in broods of the barn owl (Tyto albaL.) showed a lower humoral immune response than their senior siblings. In contrast, the cell‐mediated immune response of senior chicks in broods of the great tit (Parus majorL.) was not significantly greater than that of their junior siblings.

In line with the prediction of the TCH for the distribution of parasites among hosts, the flyCarnus haemapterusNitzsch infested junior chicks in larger numbers than senior chicks in both barn owl and kestrel (Falco tinnunculusL.) broods.

In conflict with the TCH, ticks (Ixodes ricinusL.) were distributed randomly with respect to hatching rank in broods of the barn owl and the great tit. Moreover, louse‐fliesCrataerina melbaeRondani infested mainly senior chicks instead of junior chicks in the Alpine swift (Apus melbaL.).

Summarizing, the present descriptive study indicates that the distribution of ectoparasites within‐broods is not generally governed by rank‐related variation in host defence of chicks as initially suggested by the TCH. We argue that specific aspects of the morphology, life history and ecological requirements of various ectoparasite species need more consideration as to explain the dynamics and evolution of host–parasite interactions.
Taxonomic distinctness and environmental assessment
Authors: WARWICK R. M. , CLARKE K R.
Published: March 2003

The objectives of this paper are to test the performance of the taxonomic distinctness index, δ+, in a number of environmental impact scenarios, to examine its relationship with functional diversity and to examine the influence of habitat type and diversity on the index.

The index was applied to data on free‐living marine nematodes from the coasts of Britain and Chile.

The taxonomic distinctness of nematodes from environmentally degraded locations was generally reduced in comparison with that of more pristine locations, often significantly so.

Some habitat types may have naturally lower values of taxonomic distinctness than others. However, unless the habitats are degraded in some way the δ+ values do not generally fall below the lower 95% confidence limit of the simulated distribution under a null hypothesis that the assemblages behave as if they are a random selection from the regional species pool. This ameliorates the problem encountered with species richness measures of biodiversity, which are much more strongly affected by habitat type and complexity, thus making comparisons difficult between data sets from different habitats or where habitat type is uncontrolled.

Taxonomic distinctness in marine nematodes is shown to be related to trophic diversity: a reduction in trophic diversity will lead to a reduction in taxonomic distinctness, although not necessarily to a reduction in species richness. Trophic composition itself is clearly affected by pollution, but is also strongly responsive to the major influence of habitat type.

These features of the taxonomic distinctness index, coupled with its lack of dependence on sampling effort or differences in taxonomic rigour between workers and a statistical framework for the assessment of the significance of departure from expectation, suggest that it may prove to be a biologically and ecologically relevant measure of biodiversity.

This paper demonstrates that the taxonomic distinctness index has a number of theoretical and logistical advantages over measures of species richness for the purposes of environmental assessment.
Raptor distribution in relation to landscape composition in semi‐arid Mediterranean habitats
Authors: Sánchez‐Zapata José. A. , Calvo José F.
Published: March 2003

1. Breeding sites of raptors were studied in relation to land‐use and edge habitat using two different scales in semi‐arid Mediterranean landscapes in south‐eastern Spain. Habitat relationships were analysed using Generalized Linear Models.

2. The proportion of forest cover at a small scale was the best predictor for all species. At a larger scale, the proportion of forest cover was also a good predictor, and the amount of edge habitat between forest and extensive agriculture was a very good predictor of booted and short‐toed eagle densities.

3. Models for sedentary species of raptor were similar using both scales whereas trans‐Saharan migrant raptors seemed to be more sensitive to larger landscape features that included longer edges between forest and extensive agriculture.

4. Habitat mosaics created by forestry and traditional farming were especially important for Mediterranean raptors. Strengthening of the Agri‐environmental Regulation (2078/92) will be necessary to compensate for agricultural intensification proposals promoted under the Common Agricultural Policy (CAP).
Enhancing food supplies for waders: inconsistent effects of substratum manipulations on aquatic invertebrate biomass
Authors: Sanders Mark D.
Published: March 2003

1. The potential of substratum manipulations as a technique for enhancing food supplies for waders was investigated in 98 constructed ponds at six sites in the Upper Waitaki Basin, New Zealand. Substrata were manipulated by using different construction methods, and by adding barley straw or stones to some ponds. Total invertebrate biomass and chironomid biomass were measured 3 and 15 months after ponds were constructed.

2. Food supplies in many newly constructed ponds contained large proportions of chironomid larvae, an attractive food for waders. However, this pattern was not universal; food supplies in many other newly constructed ponds were dominated by various nektonic invertebrates, or, at one site, by molluscs.

3. Food supplies developed rapidly; 3 months after construction most ponds contained similar or greater total invertebrate biomass (mean, range: 1·20, 0·10–7·66 g m−2 dry mass) and greater chironomid biomass (0·66, 0–5·41 g m−2) than nearby ‘pre‐existing’ wetlands (1·79, 0·39–6·18 g m−2 total invertebrate dry mass; 0·01, 0–0·08 g m−2 chironomid dry mass). However, ponds with stony substrata contained relatively low total invertebrate and chironomid biomass.

4. Substratum manipulations affected chironomid or total invertebrate biomass at all sites. Differences in biomass between substrata in constructed ponds were large at some sites (up to 2·7 g m−2 dry mass for chironomids, and up to 3·39 g m−2 dry mass for total invertebrates), indicating that substratum manipulations have good potential as a tool for increasing food supplies for wetland birds.

5. Despite the sometimes large effects of substratum manipulations, no technique achieved consistently positive results. The absolute and relative effects of any given substratum manipulation varied greatly among sites. This inconsistency indicates that, although substratum manipulations can be worthwhile, they need to be evaluated on a site by site basis.
Factors affecting the species composition of arable field boundary vegetation
Authors: Kleijn David , Verbeek Marein
Published: March 2003

1.  In recent decades the botanical diversity of arable field boundaries has declined drastically. To determine the most important factors related to the species composition of arable field boundaries, the vegetation composition of 105 herbaceous boundaries, 1‐m wide, in the central and eastern Netherlands was surveyed. Biomass samples of the boundary were taken at 0–33, 34–66 and 67–100 cm from the adjacent arable field.

2.  Farmers were interviewed with respect to boundary management and land use on the adjacent arable field. The two data sets containing the botanical data and the environmental variables were linked and analysed by multivariate analysis and analysis of variance.

3.  The nitrogen and phosphorus inputs to the crop were closely correlated to another environmental variable, crop rotation. Crop rotations dominated by maize cultivation received significantly higher nutrient inputs than the other rotations.

4.  Nitrogen, phosphorus and crop rotation were strongly correlated with the composition of the boundary vegetation. Species richness of the boundary vegetation was negatively related to nitrogen and phosphorus inputs to the crop, while total boundary biomass was negatively related to nitrogen inputs only. Furthermore, there was a significant relationship between the partitioning of the boundary vegetation between different functional groups and both nitrogen inputs and crop rotation on the adjacent arable field. No significant relationships were found between the vegetation composition and either herbicide use in the boundary or boundary management. This may have been due to the descriptive approach of the study: little variation in boundary management as well as herbicide use in the boundary was observed in the study area.

5.
 The boundary vegetation was characterized by a peak in biomass production in the zone near the arable field. In this zone the perennial arable weed Elymus repens, as well as annual dicot species, were significantly more abundant, while perennial dicots and monocots were significantly less abundant compared with the zones further from the arable field.

6.  Efforts to protect field boundary vegetation need to focus on a reduction or cessation of fertilizer applications in the outer metre(s) of crops that require high nutrient inputs. The determination of the exact nature of the relationship between the vegetation composition of arable field boundaries and the intuitively important management and herbicide use in the boundary requires an experimental approach.
Monitoring mammal populations with line transect techniques in African forests
Authors: Plumptre Andrew J.
Published: March 2003

1. Line transect survey techniques have been used to estimate population density for a variety of mammal species in tropical forests. In many cases indirect methods, surveying signs of animals such as counts of dung or nests, have been used because of the poor visibility in these forests. The estimates of the production and decomposition rates of these signs each have their associated errors; however, for the majority of published studies these errors have not been incorporated into the estimate of the standard errors or confidence limits of the density estimate. An equation is given showing how this should be done.

2. An equation is also given relating the resolution (R) of a density estimate to the coefficient of variation (CV) of the estimate. This shows that to detect a 10% change in a population the CV must be 3·6% (with a power of 50%) or 2·4% (with 80% power). Using this equation and data from studies in Africa, it is shown that differences of less than 10–30% change in the population are unlikely to be detected between two surveys where visual sightings of animals are made. When indirect methods of estimating the population are used, it is unlikely that less than a 30–50% change in the population could be detected.

3. Some studies have surveyed primate groups using estimates of an average group spread. Data from primate groups in Budongo Forest, Uganda, show that group spread is highly variable and varies at different times of day and between months. This survey technique is not recommended.

4. If line transects are used for monitoring populations, conversion factors should be minimized as each contributes to an increase in the CV and a reduction in the ability to detect small changes in population density.

5. Monitoring trends in abundance over several survey periods can improve the detection of change, although this is costly and requires several surveys before any conclusions can be reached. Re‐using transects in subsequent surveys can also reduce the variation around the estimate and will improve the resolution. Focusing survey efforts in areas of high density is an alternative strategy, but one that could lead to other errors as high‐density areas may be the safest and hence the last to show change. Using biased survey methods is also a promising technique that can increase the precision of surveys. It is concluded that a combination of different survey methods will ensure that changes in abundance are identified.
Effects of intensive harvesting on moose reproduction
Authors: Laurian Catherine , Ouellet Jean‐Pierre , Courtois Réhaume , Breton Laurier , St‐Onge Sylvain
Published: March 2003

1. It has been hypothesized that a balanced adult sex ratio is necessary for the full participation of ungulate females in reproduction and therefore high productivity. We tested this general hypothesis by combining two complementary approaches.

2. First, using telemetry (n = 60) and annual aerial censuses between 1995 and 1998, we compared two mooseAlces alcespopulations in Quebec, Canada, one non‐harvested and the other subject to intensive sport harvesting from the end of September to mid‐October. We tested the following predictions for the harvested population: (i) females increase movements and home ranges during the mating period; (ii) the mating system is modified, with the appearance of groups of one male and many females; (iii) subadult males participate in reproduction; (iv) the mating period extends over two to three oestrus cycles; (v) the calving period extends over several months; and (vi) productivity declines.

3. Daily movements and home range sizes during the mating period did not differ between harvested and non‐harvested populations. Most groups observed were male–female pairs. Subadult males (1·5–2·5 years old) were only observed with females in the harvested population. Mating and calving periods did not differ between populations. The proportion of females that gave birth and the number of calves produced were also comparable in the two populations.

4. Secondly, we also assessed the existence of a relationship between population productivity and percentage of males in various management units of the province of Quebec that were characterized by a wide range in sex ratios. Contrary to prediction (vi), the number of calves per 100 adult females was not related to the percentage of adult males in the population.

5. The participation of young adult males (subadults) in reproduction in our harvested population may have compensated for the lower percentage of adult males, and thus productivity was unaffected. We therefore reject the hypothesis that intensive harvesting, at least at the level we observed, affects reproduction and population productivity.

6. As there are some uncertainties regarding the long‐term effects of high hunting pressure, however, managers should favour sex ratios close to levels observed in non‐harvested populations.