Nesting habitat overlap between the Common Buzzard Buteo buteo and the Lesser Spotted Eagle Clanga pomarina for conservation planning in Natura 2000 sites

Capsule: The nesting habitat of the Common Buzzard Buteo buteo and Lesser Spotted Eagle Clanga pomarina extensively overlap, indicating that they exploit similar resources.

Aim: We aimed to determine the overlap in the nest platforms, nest trees and nest stands used by these raptors, find any evidence for the avoidance of the larger Lesser Spotted Eagle by the smaller Common Buzzard, and provide conservation implications for habitat protection of the former species in habitats that overlap extensively.

Methods: Nest sites were mapped during 2012–2014 in the Bir?ai Forest Spatial Protection Area, northern Lithuania. Fifty-three nest sites occupied by Common Buzzards and 26 by Lesser Spotted Eagles were compared.

Results: The nest platforms of both raptors were similarly placed in the tree canopies. Most Lesser Spotted Eagle nests were built in spruce, while the Common Buzzard usually nested in birch. The nest stands of the eagles were on wetter soil and located closer to the forest edge than those of the buzzards, otherwise, the nest stands did not differ significantly. There was no evidence for spatial avoidance of the larger raptor by the Common Buzzard.

Conclusions: The different components of the nesting habitats extensively overlapped, and the distribution of the interspecific pairs lacked spatial avoidance. We suggest that the nest sites of both raptors were a largely shared resource, especially if located close to the forest edges. We propose, as a rule of thumb, applying protection by way of buffer zones around buzzard nest sites if they are located close to eagle nest sites and the forest edge.     

Nest timing,nest site selection and nest structure in a high latitude population of Bearded Reedlings Panurus biarmicus

Capsule: Bearded Reedlings Panurus biarmicus show consistent nest timing, select old, compacted areas of reed when positioning their nests, and may adjust nest structure in relation to local reed characteristics and temperature.

Aims: To investigate the nest timing, nest site selection and nest structure of a rare and elusive passerine, the Bearded Reedling at the northern limit of this species’ range.

Methods: A sample of Bearded Reedling nests from the Tay Reedbeds in Scotland were located and monitored with regard to the timing of nesting, fate, fine-scale habitat characteristics and nest structure.

Results: First egg dates and brood sizes were consistent between years of the study despite variation in spring temperatures. Bearded Reedlings nested within unmanaged patches of reed, positively selecting deep leaf litters and compacted reed. Attributes of nest structure, namely internal and external diameter, were influenced by nest site characteristics and local temperature.

Conclusion: Despite a limited sample size, the study suggests that reedbed management should ensure adequate areas of old, dry and unmanaged reed are available when aiming to encourage breeding Bearded Reedlings. Additionally, the apparently flexible structure of the nest may assist this species when coping with changeable climatic conditions.     

震旦鸦雀在镶嵌型芦苇收割生境中的巢址选择

大规模的芦苇收割会对在该生境中繁殖的鸟类产生严重影响。为降低芦苇收割对鸟类繁殖的负面影响,许多地区的湿地管理者逐渐采用了镶嵌型的芦苇收割方式。但是,这种新的芦苇管理方式对鸟类繁殖期生境选择的作用机理尚不清楚。震旦鸦雀是一种主要分布在我国东部、完全依赖芦苇生境而生存的珍稀鸟类,已被IUCN定为全球性近危物种。大规模的芦苇收割导致其适宜生境丧失,被认为是该物种面临的一个主要威胁。选择山东黄河三角洲国家级自然保护区为研究地区,采用AIC信息准则法,从巢址微生境、巢域斑块和全模型3个水平上对可能影响震旦鸦雀巢址选择的生境因子进行了逻辑斯蒂回归分析,并重点探讨芦苇镶嵌收割对其巢址选择的影响以及不同水平的相互效应。结果发现,震旦鸦雀的巢址选择受巢址微生境和巢域斑块尺度双重水平的影响,但巢址微生境因子的影响要大于巢域斑块因子。在巢址微生境水平上,影响震旦鸦雀巢址选择的因素有:1.5—2.5 m旧芦苇的密度、2.5 m以上新芦苇的密度、香蒲密度和巢的可见度;在巢域斑块水平上,影响因素包括芦苇生境类型、旧芦苇斑块面积的比例和植被盖度;在综合模型中,影响因素有1.5—2.5 m旧芦苇的密度、2.5 m以上新芦苇的密度、香蒲密度、巢的可见度和植被盖度。综上,震旦鸦雀倾向于在植被盖度较高、具有一定比例(18.3%)旧芦苇面积、1.5—2.5 m旧芦苇密度较高、可见度较低的生境斑块中筑巢。研究中,78.7%(n=141)的震旦鸦雀将巢筑在新旧芦苇混合的微生境中,其中36.9%的巢址附近旧芦苇的比例在一半以上;53.2%(n=111)的巢筑于新、旧两种芦苇茎秆之上,22.3%的巢的支撑芦苇中旧芦苇所占比例在一半以上。研究结果表明,旧芦苇在震旦鸦雀巢址选择和筑巢过程中发挥了重要作用。由于大范围的芦苇收割在微生境水平上可降低1.5—2.5 m旧芦苇的密度,在巢域斑块尺度上可降低旧芦苇斑块面积的比例,因此建议,在震旦鸦雀的繁殖地,未来的芦苇收割应采用镶嵌收割的形式,并至少应保留面积在20%以上的结构较好的旧芦苇斑块,以供震旦鸦雀选择巢址和繁衍后代。     

Salt marsh elevation is a strong determinant of nest‐site selection by Clapper Rails in Georgia,USA

As sea levels rise, birds nesting in coastal marshes will be particularly vulnerable to increased tidal inundation. Understanding how marsh birds select their nesting habitat along the elevational gradient of these marshes will provide insight into how these species might be affected by rising sea levels. Clapper Rails (Rallus crepitans) are coastal marsh‐nesting birds whose nests are vulnerable to flooding, but it is not clear if they select for habitat along the elevational gradient or only use other habitat cues. Our objective was to determine if Clapper Rails select higher‐elevation nest sites, while also controlling for selection of other habitat variables at both landscape and territory levels, by comparing nest habitat to habitat in other areas of territories and at random points in the marsh landscape. At the landscape level, Clapper Rails did not exhibit selection for the elevational gradient, with nests and random points at similar elevations. At the territory level, however, nest‐site selection was most influenced by elevation and plant height, with Clapper Rails selecting nest sites with higher elevations and in areas with taller plants. However, the strength of the elevation effect was uncertain, suggesting the importance of precise elevation measurements in the field. Given this selection for higher‐elevation nest sites, Clapper Rails may be somewhat resilient to increased tidal inundation. However, the potential for increased intra‐ and interspecific competition for high‐elevation marshes should make conservation of these habitats a priority.     

Breeding ecology of the Eastern Great Reed Warbler Acrocephalus arundinaceus orientalis at Lake Kasumigaura,central Japan

CapsuleTwo populations of the Eastern Great Reed Warblers, one close to settlements and one far away, differed mainly in nest losses which were higher at the latter site.

Aims To compare the breeding ecology of two Japanese populations, and with breeding data from Polish sites.

Methods We studied two sites in 1996. The Seimei site comprises a natural reed-bed (Phragmites australis) (2.0 ha) c. 2 km from residential areas. The Sakura site occurs as smaller reed-bed (0.8 ha) close to residential areas. Field study comprised mainly nest searching and nest monitoring.

Results Breeding density, nest height, number of stems supporting nest, clutch size and brood size were not significantly different between sites. The proportion of nests built on reed stems standing in the water (60%) was significantly higher at the Seimei site (P < 0.001), and the warblers in this habitat experienced significantly higher nesting failure (P < 0.05). Predation was a principal cause of failure at both sites. Significantly more nests suffered from predation at Seimei (53%) than at Sakura (16%). Breeding density was higher at both sites compared with European populations but it fell within ranges of other Japanese populations. Mean first-egg date of first brood does not differ between our sites and Polish ones.

Conclusion The differences between the two Japanese populations and between Japanese and Polish populations were relatively small and were seen mainly in nest losses, breeding density and proportion of nests built over water.     

Effect of nest-site microclimatic conditions on nesting success in the Lesser Kestrel Falco naumanni

Capsule: Microclimatic conditions in the nests of the Lesser Kestrel Falco naumanni, particularly the percentage of time of extremely low humidity, affect breeding success.

Aim: To study the effect of within-nest temperature and humidity on nest productivity, and the correlation between nest productivity and the order of dates on which nests were occupied by the parents. To compare microclimatic conditions in the nest, breeding success and order of occupation between nests under tile roofs and in artificial nest boxes.

Methods: Three different Lesser Kestrel colonies were monitored in Israel – one rural, one urban and one in an open country habitat. Data loggers were placed in 39 nests for the entire breeding period to measure temperature and humidity. The number of fledglings was recorded for each nest, as well as the date of occupation.

Results: Full microclimatic data from 35 nests suggest that percentage of time of extremely low humidity is the major predictor of nest productivity – low humidity is negatively correlated with nest productivity. Sites of more successful nests were occupied earlier. Considering only successful nests, the urban colony had the lowest breeding success of the three colonies. There was no significant difference in mean productivity between nests in roofs and nest boxes, but nests in roofs were occupied earlier.

Conclusion: Nest microclimate, particularly low humidity, affects nesting success in addition to colony location.     

Nest site selection and patterns of nest re-use in the Hooded Crow Corvus cornix

Capsule: Hooded Crows Corvus cornix selected nesting trees based on species, height, grouping and distance from an occupied house. Nest re-use was common and pairs that re-used old nests produced more fledglings than those that built a new nest.

Aims: To determine the features of trees that influenced whether they were used by Hooded Crows as nest sites, to establish what factors influenced nest re-use between years and to explore potential costs or benefits of nest re-use.

Methods: In a large area of Orkney, Scotland, the features of trees that contained a Hooded Crow nest were compared to those of trees where nests were absent. Patterns of nest re-use between years were examined in relation to the availability of alternative sites, previous nesting success and the number of equivalent options to the tree used previously within 200?m of this site.

Results: Hooded Crows favoured spruce and pine trees as nest sites, above the most locally abundant tree species, elder and willow. Preference for trees increased with tree height, local tree density and distance from occupied houses. Over half of the crows studied re-used an old nest when one was available and crows that re-used an old nest fledged more offspring than those that built a new nest. The likelihood of a new nest being built increased as the number of potential locations to build increased. Territories where a nest survived the winter were more likely to be reoccupied the following year than those where nests fell, while territories with fewer trees around the old site were most likely to be abandoned, suggesting that those were territories of lower quality.

Conclusions: Hooded Crows displayed strong preferences for nest sites that might favour nesting success by offering concealment, shelter and protection from ground-based predators. Nest re-use was common, especially when alternative sites were scarce, and appeared to facilitate greater reproductive output.     

Dynamic risk assessment: does a nearby breeding nest predator affect nest defence of its potential victim?

There is growing evidence that birds are able to discriminate different types of nest intruders and adjust their nest defence behaviour according to intruder dangerousness and distance from the nest (the dynamic risk assessment hypothesis). Here, we tested whether birds’ decisions about nest defence may additionally be affected by an increasing familiarity with a particular nest predator. We tested nest defence responses of great reed warblers Acrocephalus arundinaceus to a nest predator, the little bittern Ixobrychus minutus. Great reed warbler nests located close (≤7 m) to synchronously breeding little bitterns were “neighbour”, other nests were “solitary”. Great reed warbler specific aggression towards a little bittern dummy was much lower (~5-times) at neighbour than solitary nests. In contrast, generalised responses to a control innocuous intruder (the turtle dove, Streptopelia turtur) were statistically identical at neighbour and solitary nests. These patterns are in line with dynamic risk assessment hypothesis. We hypothesise that decreased great reed warbler aggression at neighbour nests also represents a specific behavioural adaptation to nesting in association with the little bittern. Little bitterns breeding closer to great reed warblers showed decreased risks of failure due to predation. However, further research is needed to experimentally test the causal links behind these patterns.     

Breeding habitat and nest‐site selection by an obligatory “nest‐cleptoparasite”, the Amur Falcon Falco amurensis

The selection of a nest site is crucial for successful reproduction of birds. Animals which re‐use or occupy nest sites constructed by other species often have limited choice. Little is known about the criteria of nest‐stealing species to choose suitable nesting sites and habitats. Here, we analyze breeding‐site selection of an obligatory “nest‐cleptoparasite”, the Amur Falcon Falco amurensis. We collected data on nest sites at Muraviovka Park in the Russian Far East, where the species breeds exclusively in nests of the Eurasian Magpie Pica pica. We sampled 117 Eurasian Magpie nests, 38 of which were occupied by Amur Falcons. Nest‐specific variables were assessed, and a recently developed habitat classification map was used to derive landscape metrics. We found that Amur Falcons chose a wide range of nesting sites, but significantly preferred nests with a domed roof. Breeding pairs of Eurasian Hobby Falco subbuteo and Eurasian Magpie were often found to breed near the nest in about the same distance as neighboring Amur Falcon pairs. Additionally, the occurrence of the species was positively associated with bare soil cover, forest cover, and shrub patches within their home range and negatively with the distance to wetlands. Areas of wetlands and fallow land might be used for foraging since Amur Falcons mostly depend on an insect diet. Additionally, we found that rarely burned habitats were preferred. Overall, the effect of landscape variables on the choice of actual nest sites appeared to be rather small. We used different classification methods to predict the probability of occurrence, of which the Random forest method showed the highest accuracy. The areas determined as suitable habitat showed a high concordance with the actual nest locations. We conclude that Amur Falcons prefer to occupy newly built (domed) nests to ensure high nest quality, as well as nests surrounded by available feeding habitats.     

DO NEST SITE CHARACTERISTICS AFFECT THE BREEDING SUCCESS OF RED BISHOPS EUPLECTES ORIX?

Summary

Ferguson, J.W.H. 1994. Do nest site characteristics affect the breeding success of Red Bishops Euplectes orix? Ostrich 65:274-280.

A colony of Red Bishop birds Euplectes orix in a reed bed near Pretoria was studied during two breeding seasons. Breeding activity was greater during the second year, following increased rainfall. Predation was the most important source of mortality with 25–30% of the nests yielding fledglings. Between 7 and 11% of the nests were parasitised by Diederik Cuckoos. Reed height and distance from the edge of the reed bed were strongly correlated with nest density. From a temporal perspective breeding success was highest in late January following the peak in breeding activity. These observations suggest that overall breeding success is higher when nest densities are low. The mean fledging rate per nest was lower in areas of high nest density. This was, however, a statistical artifact. Multivariate analyses could not identify any environmental factors as predictors of breeding success within a colony.     

Nest survival of Woodpigeons (Columba palumbus) in North African forests

Capsule The nesting success of the Woodpigeon Columba palumbus in oak forests in Morocco is affected by human disturbance and nest-site characteristics.

Aims To determine factors affecting the nesting success of Woodpigeons subject to two levels of disturbance in a holm oak Middle Atlas forest.

Methods Woodpigeon nests were monitored in highly disturbed (n?=?30) and less-disturbed sites (n?=?60) over two years (2010–11). Logistic-exposure models were used to estimate daily nest-survival rate and evaluate mechanisms (altitude, temporal factors, nest location, nest-site habitat and degree of human influence) affecting nest survival.

Results Daily nest-survival rate was higher in less-disturbed sites (0.987; 95% CL: 0.980–0.991) than in high-disturbance sites (0.967; 95% CL: 0.949–0.978). Increasing density of trees surrounding nest sites and distance from the nest tree to the closest track increased daily nest-survival rate.

Conclusions Less-disturbed sites confer better nesting conditions than highly disturbed ones. Management measures should control the access of vehicles, especially trucks, in the forest of the Middle Atlas and introduce a grazing regime that will allow the forest regeneration, which would improve Woodpigeon nesting success by increasing the density of holm oak trees.     

Do alien predators pose a particular risk to duck nests in Northern Europe? Results from an artificial nest experiment

Several alien predator species have spread widely in Europe during the last five decades and pose a potential enhanced risk to native nesting ducks and their eggs. Because predation is an important factor limiting Northern Hemisphere duck nest survival, we ask the question, do alien species increase the nest loss risk to ground nesting ducks? We created 418 artificial duck nests in low densities around inland waters in Finland and Denmark during 2017–2019 and monitored them for seven days after construction using wildlife cameras to record whether alien species visit and prey on the nests more often than native species. We sampled various duck breeding habitats from eutrophic agricultural lakes and wetlands to oligotrophic lakes and urban environments. The results differed between habitats and the two countries, which likely reflect the local population densities of the predator species. The raccoon dog (Nyctereutes procyonoides), an alien species, was the most common mammalian nest visitor in all habitats and its occurrence reduced nest survival. Only in wetland habitats was the native red fox (Vulpes vulpes) an equally common nest visitor, where another alien species, the American mink (Neovison vison), also occurred among nest visitors. Although cautious about concluding too much from visitations to artificial nests, these results imply that duck breeding habitats in Northern Europe already support abundant and effective alien nest predators, whose relative frequency of visitation to artificial nests suggest that they potentially add to the nest predation risk to ducks over native predators.

     

The influence of parent body colouration and nesting habitat on bird nest predation

ABSTRACT

Capsule: Parent body colouration and nesting habitat may influence nest predation risk and, therefore, influence parental decisions on offspring care.

Aims: To investigate the adaptiveness of bird colouration under two different habitat and light conditions.

Methods: We used painted polyurethane dummies to simulate parental presence near nests, where some dummies were red, and others were cryptic brown. We placed artificial nests on trees in open and forested areas, along with two quail eggs and parental dummies.

Results: The results showed major predation on nests of the open area, however, we found no significant effect of parent colour on nest predation.

Conclusion: We suggest that the costs involved with nest site selection may overcome the costs of colouration in species that occur in these environments.     

Lesser Scaup Nest Success and Duckling Survival on the Yukon Flats,Alaska

Abstract: Over the last 20 years scaup numbers have declined, and these declines have been greatest in the northern boreal forests of Canada and Alaska where most lesser scaup (Aythya affinis) nest. We studied nest success and duckling survival of lesser scaup over 3 field seasons, 2001–2003, on the Yukon Flats National Wildlife Refuge in northeastern Alaska, USA. Daily survival rate (DSR) of nests on our study area across all 3 years was 0.943 (n = 177 nests, 95% CI: 0.930–0.954), corresponding to a nest success of only 12.3%, considerably lower than published estimates of an average nest success as high as 57% for lesser scaup in the northern boreal forest. With Mayfield logistic regression, we investigated effects on nest survival of year, clutch initiation date, and nesting habitat type (large wetlands >10 ha, small wetlands <10 ha, and wooded creeks). Neither year nor clutch initiation date influenced nest survival; however, the odds of nest success on large wetlands was 49% lower than on wooded creeks (odds ratio = 0.512, 95% CI = 0.286, 0.918). Based on the model that used only habitat type for estimation, DSR on large wetlands was 0.931 (corresponding nest success = 7.6%), DSR on small wetlands was 0.941 (nest success = 11.1%), and DSR on wooded creeks was 0.963 (nest success = 26.2%). To estimate duckling survival, we monitored 10 broods (n = 75 ducklings) over 3 field seasons by radiotagging hens at nest hatch. Most duckling mortality (94%) occurred in the first 10 days after hatch. Average duckling survival during 1–10 days was 0.321 (95% CI: 0.122–0.772), during 11–20 days was 0.996 (95% CI: 0.891–1.040), and during 21–30 days was 0.923 (95% CI: 0.769–1.041). Three of 10 hens moved all or part of their broods overland between nesting and brood-rearing wetlands for distances of 0.3–1.6 km. Our estimates of lesser scaup nest success and duckling survival on the Yukon Flats were among the lowest ever reported for ducks nesting at northern latitudes, even though the study site was in pristine boreal forest. Estimating and comparing scaup demographic rates from different geographic areas can contribute to improved conservation. Given the scarcity of information on scaup nesting in the boreal forest, basic nesting parameters are important to those trying to model scaup population dynamics.     

Factors influencing the nesting success of Lapwings Vanellus vanellus and behaviour of Red Fox Vulpes vulpes in Lapwing nesting sites

Capsule Lapwing nest predation was negatively correlated to nest density, while Lapwing alarm duration in response to foxes was positively correlated with the number of Lapwing broods present.

Aims To identify factors affecting Lapwing nest predation and Red Fox search effort.

Methods Lapwing nest success was monitored at four sites in 1996, seven sites in 1997 and six sites in 1998. In 1997 we mapped the position of all Lapwing nests in order to determine distances between nests, and the proximity of linear features and potential avian predator perches to each nest. From April to June 1998 we carried out 199 hours of nocturnal observations at six Lapwing nesting sites using night vision equipment.

Results The risk of nest predation was significantly higher for more isolated nests. Nocturnal observations showed that of all the nocturnal predators, foxes were the most active at Lapwing nesting sites. However, fox search effort in Lapwing colonies was relatively low, averaging 57 s/ha per visit. Foxes spent significantly longer foraging near breeding Lapwings (measured as duration of alarm calls) when more broods were present. Fox search effort (s/ha per hour of observation) tended to be greater in areas of high waterbird density.

Conclusion The lack of positive density-dependent nest predation, the relatively low search effort of foxes near Lapwing nesting sites and the high nest success sometimes achieved in areas with foxes all suggest that Lapwing nest predation by foxes is ‘incidental’. Lapwing chicks are probably more vulnerable to predation by foxes than clutches.     

Breeding ecology and habitat selection of Merlin Falco columbarius in forested landscapes

Capsule: Long-term trends in Merlin Falco columbarius breeding performance remained stable during a period of extensive afforestation in Ireland, where Merlin predominantly select conifer plantations for nesting.

Aims: To determine breeding performance and habitat selection of Merlin in a landscape significantly altered by afforestation.

Methods: We compiled data on Merlin to determine long-term trends in breeding performance and to examine habitat selection in a country with one of the fastest rates of afforestation in Europe.

Results: Merlin predominantly nested in trees (99.5%; n?=?183 pairs), with a strong preference for conifer plantations, which accounted for over 12 times more nests than expected by random selection. Moors and heathland were strongly selected as land-uses adjacent to nest sites. Most nests were located within 10?m of the forest edge, and in forests aged between 31 and 40 years. Merlin showed positive selection for moors and heathland, peat bogs and natural grasslands within breeding territories, and breeding success was positively related to the proportion of these land-uses surrounding nests. Breeding was successful for 74% of nests (n?=?300), and mean productivity was 2.1 young per breeding attempt (n?=?265) between 1982 and 2014. Breeding parameters remained constant over the 33-year study period, despite an increase of more than 75% in forest cover during this time.

Conclusion: Merlin breeding performance showed no long-term effects of increased afforestation. Although Merlin predominantly nested in conifer plantations, the presence of nearby open suitable foraging habitats influenced nest site selection and breeding success. The nesting preference of Merlin makes them vulnerable to disturbance from forest operations, which requires mitigation.     

Nest-site selection and characteristics in a mixed-species colony of Avocets Recurvirostra avosetta and Black-winged Stilts Himantopus himantopus

Capsule Causes of breeding failure determined optimal nest location, Black-winged Stilts being better adapted than Avocets to nest close to water.

Aims To compare nest size and location between the two species and to test whether there were inter-species differences that might suggest specific nesting adaptations, and to investigate possible correlates between hatching success and nest location.

Methods Nest-site selection, characteristics and hatching success were studied during 1989 in a large mixed-species colony located in southern Spain.

Results Black-winged Stilt nests differed in composition and size depending on distance to water (nests touching the water were larger and included mud), but Avocet nests did not. Avocets nests were more aggregated and central within the colony than those of Black-winged Stilts. Causes of breeding failure were flooding and rat predation. Successful or unsuccessful Black-winged Stilt nests did not differ significantly in characteristics or location. Successful Avocet nests were further from water than flooded nests and further from dry land than depredated ones. Distance to the centre of the colony did not affect hatching success.

Conclusion Black-winged Stilts were better adapted than Avocets to nest near water, due to their greater plasticity in nest-building behaviour. Causes of breeding failure determined optimal nest location.     

Variation in nest composition and abundances of ectoparasites between nests in colonially breeding Common Eiders Somateria mollissima

Capsule: The occurrence of high numbers of ectoparasites in nests of Common Eiders may be related to nest densities and nesting behaviour.

Aims: To estimate abundances of ectoparasites and occurrence of blood-covered eggs, and relate those to nest bowl ages, nest bottom material and the incubation stages of eggs, in nests at two different Common Eider colonies.

Methods: Nests were collected at Hvallátur and Rif, two sites at Breiðafjörður, West Iceland, in June and July 2012. The nest bottom material was classified to vegetation species and invertebrates were identified to species when possible.

Results: The flea Ceratophyllus garei was the dominant ectoparasite at both sites, with median abundances higher at Hvallátur than at Rif in June. In July, the mean abundance of fleas was higher than observed in June at Rif. There were positive relationships between the flea abundances and the incubation stages of the nests, the blood cover of the eggs and the type of nesting material. No relationship was observed between the age of nesting bowls and adult flea abundances.

Conclusion: Disadvantages of large parasite loads on the later nesters (second clutch in each nest) at Rif may be compensated by shared nest attendance and the concurrent added time for preening for females while other females attend their nests.     

Anti-predator function of not covering eggs in the initial phase of nesting in Grey Partridge Perdix perdix: a field experiment

ABSTRACT

Capsule: An experiment in the field supports the hypothesis that Grey Partridges Perdix perdix purposely expose their first laid eggs in order to test the predation risk at their nest site.

Aims: To test the hypothesis that female Grey Partridges leave first laid eggs uncovered to assess the predation risk at their chosen nesting site.

Methods: Four area-independent experiments with artificial nests were used. Predation risk was estimated by daily nest failure rate. Generalized linear mixed-effects models were used in statistical analysis.

Results: We found that Grey Partridge females could predict nest site safety. At nest sites where the first uncovered egg was depredated, there was a higher predation risk for the whole clutch.

Conclusion: Our data statistically support the hypothesis that leaving the first egg uncovered serves to provide a more conspicuous bait for potential predators and could be a female tactic for better recognizing predation risk at a nesting site. Thus, if the first uncovered egg is depredated, the female may start a new clutch elsewhere without wasting investment in the clutch at a site under high predation risk.     

Long-term trends in the nest survival and productivity of the Lesser Spotted Woodpecker Dryobates minor in Britain

ABSTRACT

Capsule: There has been no trend in nest survival of Lesser Spotted Woodpecker Dryobates minor in the 70 years since the 1940s whereas the numbers of young per nesting attempt has declined. Late nests in any year are now significantly less productive than early ones.

Aims: To test whether there has been a long-term decline in the nest survival and productivity of the Lesser Spotted Woodpecker in Britain.

Methods: Breeding data from 331 nests over the period 1949–2019 have been analysed. There were three sources – nest records submitted to the British Trust for Ornithology, a study by the Royal Society for the Protection of Birds from 2006 to 2009 and records submitted to the Woodpecker Network from 2015 to 2019. Generalized linear models were used to analyse the records for first egg date, clutch size, numbers of young fledged, and numbers of nest days for which the nest was under observation. Data were grouped into three periods reflecting population trends of the bird (pre-1980, 1980–1999, 2000–2019) and we also analysed trends with year and spring temperature.

Results: There was no trend in first egg date up to 1980 but subsequently it has advanced by 13 days. The mean clutch was 5.3 with no trend with period or year. There were no trends in nest survival during the egg stage or chick rearing. The mean number of young fledged was 2.6, with nests since 1980 fledging lower numbers of young than those pre-1980 and a decline with year. Loss of chicks, probably to starvation, was the main cause of low productivity. In the last period (2000–2019) nests started early in the season fledged more young than those started later, a trend not apparent in the earlier periods.

Conclusions: Low productivity is a widespread problem for the Lesser Spotted Woodpecker which has probably been exacerbated by the trend towards warm springs.