scholarly journals Habitat structure and diversity influence the nesting success of an endangered large cavity-nesting bird, the Southern Ground-hornbill

Koedoe ◽  
2017 ◽  
Vol 59 (1) ◽  
Author(s):  
Leigh Combrink ◽  
Hendrik J. Combrink ◽  
André J. Botha ◽  
Colleen T. Downs
Keyword(s):  
Habitat Structure ◽  
Bird Species ◽  
Nesting Success ◽  
Bush Encroachment ◽  
Data Set ◽  
Large Herbivores ◽  
Term Survival ◽  
Nest Sites ◽  
Large Trees

Habitat features can have a profound effect on the nesting success of birds. Savannas are often managed with predators and large herbivores as priority species, with little thought to the many bird species that management decisions could affect. Using a data set spanning seven breeding seasons, we examined how nesting success of Southern Ground-hornbills (SGHs) Bucorvus leadbeateri in the Kruger National Park varied as a result of various environmental and habitat factors within a radius of 3 km surrounding the nest site. Identifying which factors affect nesting success will allow for targeted management efforts to ensure the long-term survival of SGHs both within and outside of protected areas. Habitat structure and diversity of the vegetation surrounding the nest were the most influential factors on SGH nesting success. SGHs require open grassy areas for foraging and areas with large trees for nesting. Savanna habitat drivers such as elephants and fire should be managed to ensure that sufficient large trees are able to establish in the landscape and to control for bush encroachment. This is especially important in areas earmarked for SGH reintroductions. Nest sites of SGHs should be monitored to mitigate any structural changes in the habitat surrounding the nests. Nests should be modified or artificial nest sites provided, where nests have been damaged or lost, to ensure the continued presence of these birds in African savannas.Conservation implications: Habitat structure and diversity surrounding Southern Groundhornbill nests has a significant impact on their nesting success. This highlights the importance of monitoring vegetation change in savanna habitats where they occur. Management of savanna areas should take factors that influence bush encroachment, such as fire and elephants, into account to ensure the long-term persistence of these birds.

scholarly journals Principals between exploitation and exploration: Results of a nationwide study on ambidexterity of school leaders

2020 ◽  
pp. 174114322094570
Author(s):  
Marcus Pietsch ◽  
Pierre Tulowitzki ◽  
Colin Cramer
Keyword(s):  
Dynamic Environments ◽  
Management Research ◽  
Data Set ◽  
Term Survival ◽  
Leadership And Management ◽  
Nationwide Study ◽  
Efficiency Control ◽  
Exploitation And Exploration ◽  
Discontinuous Innovation

Both organizational and management research suggest that schools and their leaders need to be ambidextrous to secure prosperity and long-term survival in dynamic environments characterized by competition and innovation. In this context, ambidexterity refers to the ability to simultaneously pursue exploitation and exploration and thus to deliver efficiency, control and incremental improvements while embracing flexibility, autonomy and discontinuous innovation. Using a unique, randomized and representative data set of N = 405 principals, we present findings on principals’ exploitation and exploration. The results indicate: (a) that principals engage far more often in exploitative than in explorative activities; (b) that exploitative activities in schools are executed at the expense of explorative activities; and (c) that explorative and ambidextrous activities of principals are positively associated with the (perceived) competition between schools. The study brings a novel perspective to educational research and demonstrates that applying the concept of ambidexterity has the potential to further our understanding of effective educational leadership and management.

scholarly journals The duration of global agri-food export competitiveness

2017 ◽  
Vol 119 (6) ◽  
pp. 1378-1393 ◽  
Author(s):  
Štefan Bojnec ◽  
Imre Fertő
Keyword(s):  
Comparative Advantage ◽  
Agricultural Land ◽  
Survival Rates ◽  
Revealed Comparative Advantage ◽  
Data Set ◽  
Term Survival ◽  
Content Type ◽  
Country Level ◽  
Export Competitiveness

Purpose The purpose of this paper is to examine the pattern, duration and country-level determinants of global agri-food export competitiveness of 23 major global agri-food trading countries. Design/methodology/approach A large panel data set is compiled to facilitate assessment of the pattern, duration and country-level determinants of global agri-food export competitiveness using a revealed comparative advantage index. Findings The results suggest that the duration of revealed comparative advantage is heterogeneous at the agri-food product level. Long-term survival rates as revealed by the comparative advantage indices are among the highest for the Netherlands, France, Belgium, the USA, Argentina and New Zealand. The level of economic development, the share of agricultural employment, subsidies to agriculture and differentiated consumer agri-food products increase the likelihood of failure in the duration of comparative advantage, while the abundance of agricultural land and export diversification reduce that likelihood. Originality/value The framework is conceptually innovative in how it models the likelihood of failure in the duration of comparative advantage and assesses implications. Export competitiveness is a crucial factor in long-term global farm business survival as it fosters opportunities for business prosperity on global markets.

scholarly journals Not so soft? Delayed release reduces long-term survival in a passerine reintroduction

Oryx ◽  
2013 ◽  
Vol 49 (3) ◽  
pp. 535-541 ◽  
Author(s):  
Kate Richardson ◽  
Isabel C. Castro ◽  
Dianne H. Brunton ◽  
Doug P. Armstrong
Keyword(s):  
Bird Species ◽  
Release Site ◽  
Immediate Release ◽  
Term Survival ◽  
Long Term Survival ◽  
Delayed Release ◽  
In Captivity ◽  
Negative Effect ◽  
Radio Transmitters

AbstractReintroduction success depends in part on the release strategy used. Benefits are attributed to particular release strategies but few studies have tested these assumptions. We examined the effect of delayed release (a form of so-called soft release) on the survival of a threatened passerine, the New Zealand hihi Notiomystis cincta, for up to 7 months after translocation. Birds were captured at the source site and then held in captivity for disease screening. They were then taken to the release site, where 30 were released immediately and 28 were held for a further 2–4 days in an on-site aviary. Twenty-four birds were fitted with radio-transmitters. A 1,300 ha area around the release site was searched fortnightly, and survival was analysed using a multi-state model that accounted for the effect of transmitters on detection probability. Our results indicated that delayed release had a negative effect on long-term survival, but no effect was apparent in the first 6 weeks. Survival probability from 6 weeks to 7 months post-release was 0.77 ± SE 0.20 for immediate-release birds and 0.04 ± SE 0.06 for delayed-release birds. Our results suggest that there is a misconception about the benefits of delayed-release strategies during translocation of wild animals. Studies that have demonstrated a benefit of delayed release in other bird species used captive-bred individuals, and we suggest that wild individuals perceive captivity differently. We recommend that biological context is considered before delayed release is used in translocations.

scholarly journals LONG-TERM SURVIVAL OF GOLDEN TRUMPET TREE AND COPPERPOD ON ROCKLAND SOIL IN SOUTH FLORIDA

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 502A-502
Author(s):  
Joe Garofalo ◽  
Ruben Regalado
Keyword(s):  
South Florida ◽  
Medium Size ◽  
Street Trees ◽  
Term Survival ◽  
Long Term Survival ◽  
Heavy Equipment ◽  
Street Tree ◽  
Large Trees ◽  
Crushed Limestone

The soil in south Miami–Dade Co., Fla., consists of 4 to 6 inches of scarified limestone, officially a “very gravelly loam”. The bedrock reaches the surface; with little weathered material or organic matter. Heavy equipment is used to break up the rock, and a rock plow is used every few years to prevent re-compaction. Street trees in swales are installed in shallow holes dug in the rock and back-filled with crushed limestone. Golden trumpet tree, or yellow tab, Tabebuia chrysotricha, and copperpod, Peltophorum pterocarpum, are deciduous, tropical trees of medium size. Both are popular throughout south Florida because they produce spectacular displays of yellow flowers before the leaves emerge in the spring. When planted on rockland soil, both species present maintenance problems which suggest that they may not be good choices for use as street trees. In Summer 2005, after three hurricanes, both species were evaluated for long-term survival. Of 246 Tabebuia, 26% fell, 18% leaned (or 45% damaged), and 25% were missing, having been destroyed in previous years. Only one was broken, the rest fell due to root failure. Six large trees growing near buildings were standing. It appears that yellow tab is not a good street tree in rockland, not even for the short-term. Of 142 Peltophorum, 23% fell, 3% leaned (or 26% damaged), and 4% were missing. Due to an umbrella-like branching pattern, 15% had branches broken on the street side, caused by vehicles, not wind. Though it sustained only half the wind damage of yellow tab, copperpod is not a good street tree, due to poor branching patterns.

Summer and winter bird populations associated with five age-classes of aspen forest in Alberta

1993 ◽  
Vol 23 (9) ◽  
pp. 1830-1836 ◽  
Author(s):  
D. A. Westworth ◽  
E. S. Telfer
Keyword(s):  
Habitat Structure ◽  
Bird Species ◽  
Canopy Cover ◽  
Species Number ◽  
Age Classes ◽  
Bird Populations ◽  
Clear Cut ◽  
Number Of Species ◽  
Bird Density ◽  
Large Trees

Summer and winter bird use of aspen forests was studied in west central Alberta. Forest age-classes in the study included 1- and 2-year-old clear-cut areas and.14-, 30-, 60-, and 80-year-old stands. Habitat structure and composition were quantified by a combination of measurement and estimation of variables. Density of the breeding bird population was estimated by territorial mapping. Changes in habitat structure between different age-classes resulted in a successional replacement of bird species. Number of individuals was greatest in 14-year-old stands at 656 territories per 100 ha, probably owing to the presence of remnant snags and of large trees that had survived past fires. The 30-year-old stands supported 312 territories per 100 ha, 60-year-old stands 380 territories, and 80-year-old stands 231 territories, respectively. Recently clear-cut areas supported only 110 territories. Number of species followed the same pattern with 25 in 14-year-old stands, 22 in the 30-year-old stands, 21 in the 60-year-old stands, and 14 in the 80-year-old stands. Recent clearcuts supported 10 species. In winter 13 bird species were recorded in the combined clear-cut, 14-, 30-, and 60-year-old stands. The highest number of species (11) were recorded in the 60-year-old stand during winter but the greatest winter bird density (125 individuals/100 ha) occurred in the 30-year-old stand. Three principal components extracted from the habitat data explained 83.2% of the variance in bird use. The components corresponded to gradients in canopy cover, occurrence of conifers, and shrub density.

Rainfall and grazing: not the only barriers to arid-zone conifer recruitment

2017 ◽  
Vol 65 (2) ◽  
pp. 109 ◽  
Author(s):  
Heidi C. Zimmer ◽  
Singarayer K. Florentine ◽  
Rita Enke ◽  
Martin Westbrooke
Keyword(s):  
Arid Zone ◽  
Stand Density ◽  
Grazing Pressure ◽  
Large Herbivore ◽  
Large Herbivores ◽  
South Wales ◽  
Large Trees ◽  
Callitris Glaucophylla ◽  
And Control

An understanding of the drivers of infrequent recruitment is fundamental in managing for species persistence. Callitris glaucophylla Joy Thomps. & L.A.S. Johnson (white cypress-pine) is a slow-growing, long-lived conifer, with a distribution that extends across arid Australia. Arid populations of C. glaucophylla are endangered in New South Wales, and are characterised by infrequent recruitment. We examined recruitment patterns of C. glaucophylla in differential grazing exclosures (excluding rabbits, excluding large herbivores or excluding both) and in unfenced areas. More recruitment occurred in rabbit-proof exclosures, compared with nearby large herbivore and control exclosures, although some rabbit-proof exclosures recorded no recruitment. Increases in recruitment at several long-term exclosures were associated with wet periods, as was recruitment at some unfenced sites. Apart from grazing and rainfall, recruitment was related to mature tree size and stand density (probably because of their influence on seed availability). These endangered arid C. glaucophylla woodlands are all that remains of a once extensive distribution, and are habitat for a suite of threatened species. Reduction in grazing pressure, particularly from rabbits, is clearly critical to maintain recruitment in these remnant populations. Chances of recruitment appear to be enhanced in low-density stands, around large trees, and in dune blow outs – fencing should focus on these areas.

scholarly journals Bird Occupancy of a Neotropical Forest Fragment Is Mostly Stable over 17 Years but Influenced by Forest Age

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 50
Author(s):  
Marconi Campos-Cerqueira ◽  
W. Douglas Robinson ◽  
Gabriel Augusto Leite ◽  
T. Mitchell Aide
Keyword(s):  
Bird Species ◽  
Barro Colorado Island ◽  
Tropical Species ◽  
Forest Age ◽  
Forest Fragment ◽  
Long Term Effects ◽  
Old Growth ◽  
Data Set ◽  
Old Growth Forest

The effects of forest degradation, fragmentation, and climate change occur over long time periods, yet relatively few data are available to evaluate the long-term effects of these disturbances on tropical species occurrence. Here, we quantified changes in occupancy of 50 bird species over 17 years on Barro Colorado Island (BCI), Panama, a model system for the long-term effects of habitat fragmentation. The historical data set (2002–2005) was based on point counts, whereas the contemporary data set (2018) was based on acoustic monitoring. For most species, there was no significant change in occupancy; however, the occupancy of four species (Tinamus major, Polioptila plumbea, Myiarchus tuberculifer, and Ceratopipra mentalis) increased significantly, and the occupancy of three species (Saltator grossus, Melanerpes pucherani, and Cyanoloxia cyanoides) decreased significantly. Forest age explained the majority of occupancy variation and affected the occupancy of more bird species than survey period or elevation. Approximately 50% of the species seem to favor old-growth forest, and 15 species (30%) had a significantly higher occupancy in old-growth forest sites. Elevation had no significant impact on the occupancy of the majority of bird species. Although BCI has been a protected reserve for approximately 100 years, land-use legacies (i.e., forest age) continue to influence bird distribution.

scholarly journals Long-term outcomes among octogenarians with aneurysmal subarachnoid hemorrhage

2019 ◽  
Vol 131 (2) ◽  
pp. 426-434 ◽  
Author(s):  
Hormuzdiyar Dasenbrock ◽  
William B. Gormley ◽  
Yoojin Lee ◽  
Vincent Mor ◽  
Susan L. Mitchell ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Treatment Modality ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Long Term Outcomes ◽  
Data Set ◽  
Term Survival ◽  
Microsurgical Clipping ◽  
Male Sex ◽  
National Analysis

OBJECTIVEData evaluating the long-term outcomes, particularly with regard to treatment modality, of aneurysmal subarachnoid hemorrhage (SAH) in octogenarians are limited. The primary objectives were to evaluate the disposition (living at home vs institutional settings) and analyze the predictors of long-term survival and return to home for octogenarians after SAH.METHODSData pertaining to patients age 80 and older who underwent microsurgical clipping or endovascular coiling for SAH were extracted from 100% nationwide Medicare inpatient claims and linked with the Minimum Data Set (2008–2011). Patient disposition was tracked for 2 years after index SAH admission. Multivariable logistic regression stratified by aneurysm treatment modality, and adjusted for patient factors including SAH severity, evaluated predictors of return to home at 60 and 365 days after SAH. Survival 365 days after SAH was analyzed with a multivariable Cox proportional hazards model.RESULTSA total of 1298 cases were included in the analysis. One year following SAH, 56% of the patients had died or were in hospice care, 8% were in an institutional post–acute care setting, and 36% had returned home. Open microsurgical clipping (adjusted hazard ratio [aHR] 0.67, 95% confidence interval [CI] 0.54–0.81), male sex (aHR 0.70, 95% CI 0.57–0.87), tracheostomy (aHR 0.63, 95% CI 0.47–0.85), gastrostomy (aHR 0.60, 95% CI 0.48–0.76), and worse SAH severity (aHR 0.94, 95% CI 0.92–0.97) were associated with reduced likelihood of patients ever returning home. Older age (aHR 1.09, 95% CI 1.05–1.13), tracheostomy (aHR 2.06, 95% CI 1.46–2.91), gastrostomy (aHR 1.55, 95% CI 1.14–2.10), male sex (aHR 1.66, 95% CI 1.20–2.23), and worse SAH severity 1.51 (95% CI 1.04–2.18) were associated with reduced survival.CONCLUSIONSIn this national analysis, 56% of octogenarians with SAH died, and 36% returned home within 1 year of SAH. Coil embolization predicted returning to home, which may suggest a benefit to endovascular treatment in this patient population.

Influence of Age on Choice of Therapy and Surgical Outcomes in Patients with Nonsmall Cell Lung Cancer

2009 ◽  
Vol 75 (7) ◽  
pp. 598-604 ◽  
Author(s):  
William D. Bolton ◽  
David C. Rice ◽  
Arlene M. Correa ◽  
Wayne Hofstetter ◽  
Ritsuko Komaki ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Surgical Outcomes ◽  
Pulmonary Resection ◽  
The Elderly ◽  
Data Set ◽  
Term Survival ◽  
Cancer Management ◽  
Institutional Data ◽  
Surgical Data

United States census data predict expansion of the elderly population until 2050 and nonsmall lung cancer (NSCLC) incidence is expected to rise accordingly. This study examines trends of lung cancer management and outcomes for pulmonary resection of primary NSCLC in the elderly. An institutional data set (n = 5950) was examined to determine patterns of management. A separate surgical dataset (n = 1756) was examined to determine surgical outcomes. “Elderly” was defined as 70 years old or older. Twenty-four per cent of patients in the institutional data set underwent surgery. Patients in the youngest age quartile (younger than 62 years) were more likely to undergo surgery, whereas the oldest quartile (older than 74 years) were less likely. In the surgical data set, 643 patients were elderly. No difference in combined 30-day/in-hospital mortality was noted (4 vs 2.9%). Five-year survival was 59.1 per cent for younger and 49.9 per cent for elderly patients. On multivariable analysis, age 70 years or older, male gender, increasing Charlson Comorbidity Index score, and pathologic stage were predictors of worse survival. Increasing age is an independent rick factor for surgical outcome and long-term survival after pulmonary resection for NSCLC, age appears to influence choice of initial treatment and extent of resection. Although surgery in the elderly carries higher risk, long-term cure can still be achieved in a significant number of patients.

Clinical outcomes in 1731 patients undergoing mitral valve surgery for rheumatic valve disease

Heart ◽  
2017 ◽  
Vol 104 (10) ◽  
pp. 841-848 ◽  
Author(s):  
Wan Kee Kim ◽  
Ho Jin Kim ◽  
Joon Bum Kim ◽  
Sung-Ho Jung ◽  
Suk Jung Choo ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Propensity Score ◽  
Large Data ◽  
Matched Cohort ◽  
Valve Repair ◽  
Data Set ◽  
Term Survival ◽  
Significant Difference ◽  
The Impact

ObjectiveUnlike degenerative mitral valve (MV) disease, the advantages of valve repair procedure over replacement have been debated in rheumatic MV disease. This study aims to evaluate the impact of procedural types on long-term outcomes through analyses on a large data set from an endemic area of rheumatic disease.MethodsWe evaluated 1731 consecutive patients (52.3±12.5 years; 1190 women) undergoing MV surgery for rheumatic MV disease between 1997 and 2015. Long-term survival and valve-related outcomes were compared between repair and replacement procedures. To adjust for selection bias, propensity score analyses were performed.ResultsPatients undergoing repair were younger and had more predominant mitral regurgitation than mechanical and bioprosthetic replacement groups (61.6% vs 15.6% vs 24.4%; P<0.001). During follow-up (130.9±27.7 months), 283 patients (16.3%) died and 256 patients (14.8%) experienced valve-related complications. Propensity score matching yielded 188 pairs of repair and replacement patients that were well balanced for baseline covariates. In the matched cohort, there was no significant difference in the mortality risk between the repair and replacement groups (HR, 1.24; 95% CI 0.62 to 2.48). The risk of composite valve-related complications, however, was significantly lower in repair group (HR, 0.57; 95% CI 0.33 to 0.99) principally derived by a lower risk of haemorrhagic events (HR, 0.23; 95% CI 0.07 to 0.70). The incidence of reoperation was not significantly different between groups in the matched cohort (HR, 1.62; 95% CI 0.49 to 5.28).ConclusionValve repair in well-selected patients with severe rheumatic MV disease led to comparable survival, but superior valve-related outcomes compared with valve replacement surgery.

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