scholarly journals Nest-site selection by the white-tailed eagle and black stork – implications for conservation practice

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Grzegorz Zawadzki ◽  
Dorota Zawadzka ◽  
Anna Sołtys ◽  
Stanisław Drozdowski

Abstract Background Nesting trees and habitat represent the key factor underpinning stand selection by forest-dwelling birds. While two large European species – the black stork (Ciconia nigra L.) and white-tailed eagle (Haliaaetus albicilla L.) – are known to require old, large trees for nesting, we sought to investigate further by comparing species requirements at the levels of the nesting tree, nesting stand, and landscape. This entailed a detailed examination of forest features within circles of radius 15 m surrounding 16 and 19 trees holding the nests of storks and eagles respectively. The same parameters were also checked in the vicinity of 50 randomly-selected mature trees. Results Our results indicate different nesting preferences, with the eagles entirely confining themselves to Scots pine (Pinus sylvestris L.) – a species also chosen by black storks, which nevertheless regularly favour pedunculate oak (Quercus robur L.). Both species select trees of greater girth than the random ones, but white-tailed eagles choose to nest in the vicinity of patches of mature old stands with a loose canopy, to the extent that nesting trees and surrounding trees are of similar ages. In contrast, black storks prefer “veteran” trees with low-set crowns that are much older than any others in their vicinity. Nesting trees of the eagles are away from roads and close to lakes, while black storks do not avoid roads. Conclusions As the ages of nesting trees of both species are greater than ages at final cutting in this region’s managed forest, silvicultural measures will need to be adjusted, with small patches of forest spared, or larger areas as “islands” of old-growth. Likewise, as tending and thinning are engaged in, certain trees with horizontal branches will need to remain, with relict trees also left untouched. As it happens, all of these recommendations are anyway key elements of close-to nature silviculture and multifunctional forestry.

Author(s):  
Ioana Damoc ◽  
Tiberiu Sahlean ◽  
Roxana Ion ◽  
Mihaela Ion ◽  
Lotus Elena Meşter

Abstract The main goal of this study is to get a better insight of the habitat requirements for the Great- and Middle Spotted Woodpeckers. Woodpeckers are forest specialists, threatened all over Europe mainly by the loss of forest habitats and also by the loss in quality of the habitat by reducing the food sources and nesting sites. Both species showed a strong preference for oaks, lime, large trees and dead wood for nesting, but Middle Spotted Woodpecker proved to be more selective in terms of tree species. Nest-height was influenced by tree diameter. Both species have the same nesting preferences for Turkey oak, lime and Pedunculate oak, in a Quercetum farnetto-cerris type of forest. The orientation of the nest hole on the tree was mainly NE-E-SE for Middle Spotted Woodpecker and N-NE-E for Great Spotted Woodpecker.


The Auk ◽  
2001 ◽  
Vol 118 (3) ◽  
pp. 727-735 ◽  
Author(s):  
Jason Jones ◽  
Raleigh J. Robertson

Abstract We examined habitat selection by breeding Cerulean Warblers (Dendroica cerulea) at three spatial scales in eastern Ontario over three years (1997–1999). Territories were characterized by well-spaced large trees, with high canopies and dense foliage cover at heights between 12–18 m. Nesting habitat additionally was characterized by dense foliage cover above 18 m. The results of our nest-patch (0.04 ha circle around nest) and nest-site (0.01 ha circle) analyses indicate that male Cerulean Warblers may take active roles in nest-site selection when selecting territories. We conclude from our nest-patch and nest-site selection analyses that territories likely contain multiple nest patches and sites and that male Cerulean Warblers may defend areas with multiple nest patches or sites, which may attract females to settle with them. Whether or not Cerulean Warbler females use nest-site availability as a mate- or territory-choice cue remains unknown. We also tested the validity of a commonly made assumption that a random sampling of habitat by researchers is representative of the habitat actually available to birds and found that, in our study area, the assumption was invalid. Taken together, our results point toward the need to maintain sizeable stands of mature, deciduous forest to ensure the persistence of Cerulean Warblers in eastern Ontario. Population characteristics such as lower minimum area requirements and a resilience to habitat disturbance may make that an easier job in eastern Ontario than elsewhere in this species' breeding range.


2009 ◽  
Vol 18 (7) ◽  
pp. 857 ◽  
Author(s):  
Chad T. Hanson ◽  
Malcolm P. North

With growing debate over the impacts of post-fire salvage logging in conifer forests of the western USA, managers need accurate assessments of tree survival when significant proportions of the crown have been scorched. The accuracy of fire severity measurements will be affected if trees that initially appear to be fire-killed prove to be viable after longer observation. Our goal was to quantify the extent to which three common Sierra Nevada conifer species may ‘flush’ (produce new foliage in the year following a fire from scorched portions of the crown) and survive after fire, and to identify tree or burn characteristics associated with survival. We found that, among ponderosa pines (Pinus ponderosa Dougl. ex. Laws) and Jeffrey pines (Pinus jeffreyi Grev. & Balf) with 100% initial crown scorch (no green foliage following the fire), the majority of mature trees flushed, and survived. Red fir (Abies magnifica A. Murr.) with high crown scorch (mean = 90%) also flushed, and most large trees survived. Our results indicate that, if flushing is not taken into account, fire severity assessments will tend to overestimate mortality and post-fire salvage could remove many large trees that appear dead but are not.


1978 ◽  
Vol 110 (3) ◽  
pp. 301-318 ◽  
Author(s):  
K. W. Richards

AbstractThe niche breadth and overlap in nesting preferences of 15 species of bumble bees were investigated in Alberta. Some of the factors that influence the distribution of nesting sites and abundance of species and permit the species to coexist in sympatry are discussed. Artificial domiciles were used as potential nesting sites. Some species were specialists in terms of nest site selection while others were generalists. The few natural nests found, the long periods spent by queens searching for nests, the high frequency of usurpation or direct interference and death of intruders, and the frequency of high niche overlap values between species are evidence that nesting sites are limited and are incompletely partitioned among the coexisting species. Usurpation also demonstrates the competition among individuals and species. Phenological differences in nest establishment influence the competition among the species. Camouflaging of tunnels presumably reduces the intensity of usurpation and protects queens and the brood from inclement weather and from social parasites (e.g., Psithyrus) and predators.


1965 ◽  
Vol 13 (4) ◽  
pp. 593 ◽  
Author(s):  
PB Carne

The distribution of the sawfly is discussed at several levels, ranging from that within a study region which comprised a substantial proportion of the known range of the insect, to that within the crowns of individual trees. A mosaic of areas was recognized within the region, each characterized by a degree of ecological uniformity and in which saivfly populations maintained relatively high or low levels of abundance during 6 yr of observation. The distribution of the insect is influenced strongly by climatic factors, the rainfall and temperature statistics for the critical period October-March for all areas in which it occurs being closely grouped. Such grouping is even more marked for those areas in which the sawfly was consistently most abundant. The cool wet limit of the sawfly's distribution coincides with that of a favoured host species, but the hot dry limit appears to be determined by the insect's susceptibility to desiccation. Although many naturally occurring and planted eucalypts will support sawfly larvae, persistent infestations were recorded only where one or more of three species grew - Eucalyptus blakelyi, E. camaldulensis, or E. melliodora. The sawfly is an inhabitant of river valley woodland, rarely becoming abundant in other situations and being absent from sclerophyll forest formations. Survival of the insect is greatly influenced by the ease with which it can penetrate into the soil for cocoon formation; it tends to be most abundant in areas of light soil, or where large trees provide a deep litter accumulation. The susceptibility of trees to infestation is influenced by seasonal production of new foliage. Those growing in sites where the water table is high, and whose leaf production is to a large extent independent of rainfall patterns, may be subject to chronic attack. Distribution between trees is affected by their leaf shape and texture, and by their history of previous defoliation. Small trees are particularly prone to attack, and infestation of mature trees is generally an indication of outbreak abundance of the insect. Similarly, marginally favoured species are attacked only when oviposition sites on more favoured trees are virtually saturated. Field experiments indicated that an observed contagious distribution of sawfly eggs in portions of the crowns of individual trees is not the result of overt gregariousness on the part of the females, but results from the attraction of the latter to foliage of certain physical characteristics and position on the tree.


2021 ◽  
Author(s):  
Dylan Connor

This article shows that parents reveal information about their fertility behavior through how they name their children. I arrive at this finding from detailed examination of the net fertility of 130,000 married couples in Ireland circa 1910, a country known for its historically high fertility rate. After stringently accounting for the occupation, religion and location of couples, I find higher fertility rates among couples who chose distinctly Catholic names and traditional names for their children, with the latter being particularly important. Exposure to towns and cities lowered net fertility and weakened preferences for traditional and Catholic names. Cumulatively, these findings highlight the role of traditional rural norms over explicitly religious influences in driving high fertility rates in Ireland. The impact of towns and cities in reducing net fertility suggests that Ireland’s sluggish urbanization was a key factor in its high historical fertility rate.


Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1008
Author(s):  
Prem Prakash Singh ◽  
Tamalika Chakraborty ◽  
Anna Dermann ◽  
Florian Dermann ◽  
Dibyendu Adhikari ◽  
...  

The montane subtropical broad-leaved humid forests of Meghalaya (Northeast India) are highly diverse and situated at the transition zone between the Eastern Himalayas and Indo-Burma biodiversity hotspots. In this study, we have used inventory data from seedlings to canopy level to assess the impact of both biotic and abiotic disturbances on structure, composition, and regeneration potential of the Fagaceae trees of these forests. Fagaceae trees are considered as the keystone species in these forests due to their regional dominance and their importance as a fuel wood source, and also because they form an important component of climax community in these forests. Unfortunately, these forests are highly degraded and fragmented due to anthropogenic disturbances. We have assessed, for the first time, the restoration potential (i.e., capacity to naturally regenerate and sustain desired forest structure) of Fagaceae species in the genera Lithocarpus Blume, Castanopsis (D. Don) Spach, and Quercus Linn. We also evaluated how biotic and abiotic factors, as well as anthropogenic disturbances, influence the restoration potential of these species in six fragmented forest patches located along an elevational gradient on south-facing slopes in the Khasi Hills, Meghalaya. Fagaceae was the most dominant family at all sites except one site (Laitkynsew), where it was co-dominant with Lauraceae. Fagaceae forests have shown high diversity and community assemblages. Fagaceae species had high levels of natural regeneration (i.e., seedlings and saplings) but low recruitment to large trees (diameter at breast height or DBH ≥ 10 cm) at all sites. The ability to sprout was higher in Fagaceae tree species than non-Fagaceae tree species. We have shown that human disturbance and structural diversity were positively related to regeneration of Fagaceae tree species due to high sprouting. However, with increasing human disturbance, recruitment of saplings and pole-sized trees to mature trees hampered the resulting proportion of mature Fagaceae tree species. This study provides a means for assessing regeneration and a basis for forest management strategies in degraded and fragmented forests of Meghalaya.


2018 ◽  
Vol 66 (1) ◽  
pp. 26 ◽  
Author(s):  
Lynda D. Prior ◽  
Quan Hua ◽  
David M. J. S. Bowman

Callitris glaucophylla (syn. C. columellaris F.Muell.) is an iconic Australian conifer that is suffering a recruitment deficit over much of the arid zone. Here, seedling establishment requires a series of unusually wet years, and protection from high levels of herbivory. The aim of our study was to determine the size class structure of C. glaucophylla populations in the most arid part (150 mm mean annual precipitation) of its range, and particularly whether seedlings had established during a wet period in 2010/11. We sampled C. glaucophylla populations throughout the region, including inside a 6000 ha feral animal exclosure. We found no seedlings from 2010/11, except on drainage lines adjacent to roads. Of 255 plots centred on mature trees, only 2% contained older seedlings, and 8% contained saplings, with no differences inside or outside exclosure, and 84% of trees were larger than 20 cm basal diameter. Matching dates of known regeneration with long-term rainfall records suggested that successful regeneration of C. glaucophylla requires a total of 600–720 mm of rain over a 2 year period. Our radiocarbon dating showed the age of three large trees ranged from 106 to 268 years, signifying that such trees in this region likely have only 2–8 climatic opportunities to reproduce.


2009 ◽  
Vol 160 (11) ◽  
pp. 324-333 ◽  
Author(s):  
Rita Bütler ◽  
Thibault Lachat

Veteran trees and deadwood are key elements to maintain forest biodiversity. Setting aside protected forest areas and old-growth patches is a recent concept intended to favor deadwood dependent species. We compared forest areas where no harvesting occurred for at least 30 years with regularly managed forests, in order to assess the efficiency of such conservation measures. We collected data from 24 sites in Switzerland, where we inventoried dead trees and habitat structures such as cavities, cracks, bark pockets, etc. In unmanaged forests we found deadwood amounts of 98–143 m3 and 20 snags > 30 cm DBH per hectare, one and half time more large trees (> 60 cm DBH) und twice as many habitat structures as in managed forests. The latter had in average 15–19 m3 of deadwood and 3 snags > 30 cm DBH per hectare. Deadwood amounts in unmanaged forests were similar to the ones in natural forests of central Europe. However, we found 10–50 times less veteran trees (> 80 cm DBH) than in natural forests (1 vs. 0.2 trees per hectare in unmanaged vs. managed forests). For equal diameter classes, trees had more habitat structures in unmanaged than in managed forests. Forest managers plan to intensify wood harvesting in Swiss forests. Consequently, we recommend to urgently set aside protected forest areas and old-growth patches, to maintain and favor habitat trees in managed forests, and to introduce an efficient sustainable deadwood management in any forest.


Demography ◽  
2021 ◽  
Vol 58 (5) ◽  
pp. 1793-1815
Author(s):  
Dylan Shane Connor

Abstract This article shows that parents reveal information about their fertility behavior through how they name their children. I arrive at this finding from a detailed examination of the net fertility of 130,000 married couples in Ireland, a country known for its historically high fertility rate, circa 1911. After stringently accounting for couples' occupation, religion, and location, I find higher fertility rates among couples who chose distinctly Catholic names and traditional names for their children, with the latter being particularly important. Exposure to towns and cities lowered net fertility and weakened preferences for traditional and Catholic names. Cumulatively, these findings highlight the role of traditional rural norms over explicitly religious influences in driving high fertility rates in Ireland. The impact of towns and cities in reducing net fertility suggests that Ireland's sluggish urbanization was a key factor in its high historical fertility rate.


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