In Search of a Better Reporting of Scientific Results: A Data Probability Language

[Abstract] A recent paper published in Trends in Ecology and Evolution suggested a new alternative for the reporting of statistical results, using a language based on evidence against the null hypothesis. I agree that the reporting of null hypothesis statistical testing clearly needs improvement, but the proposal of an evidence-based language has several drawbacks: a) it goes back to the original Fisherian continuous interpretation of p-values, b) at the same time uses some loose categorizations and, c) most importantly, it may provide a wrong idea of what p-values actually are. By saying that there is very strong, strong, moderate, weak or little evidence of an effect, the reader gets the idea that p-values are providing Bayesian-type information on the probability of the null hypothesis given our data. However, p-values are only providing information on the probability of having obtained our data (or more extreme data), under the trueness of the null hypothesis. That is why I suggest reporting results using a data probability-based language, together with a previous and separate specification of the magnitude of the effects.AMA was supported by Xunta de Galicia, project ED431C 2018/57Xunta de Galicia; ED431C 2018/5

Rethinking conservation : towards a paradigm shift

Between the mid-1980s and the present day, conservation biology split into two almost independent fields: management ecology and conservation ecology. We have witnessed the recovery of large endangered species and a decrease in small and common species. In addition, the abandonment of rural areas has allowed the expansion of forest species and has hurt those that inhabit open spaces and who are linked to traditional farming. Many species that once lived only in refuges are now starting to venture further out and are losing their fear of humans. Moreover, environments that have become anthropic are now being successfully occupied more often. In short, we are going towards a world that reconciles humans and wildlife, which will be beneficial, but will also pose new challenges

Translocation of Bolder Birds Could Provide Benefits to Mediterranean Osprey Populations Under Current Conditions of High Human Frequentation in Natural Areas

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUGThe author was funded by Universidade da Coruña/CISUG and Xunta de Galicia ED431C 2018/57Xunta de Galicia; ED431C 2018/5

¿Es fiable la regla de oro de n = 30 de los estudios ecológicos de campo? Se debe prestar más atención a la variabilidad de nuestros datos

A common practice of experimental design in field ecology, which relies on the Central Limit Theorem, is the use of the 'n = 30 rule of thumb'. I show here that papers published in Animal Biodiversity and Conservation during the period 2010-2013 adjust to this rule. Samples collected around this relatively small size have the advantage of coupling statistically-significant results with large effect sizes, which is positive because field researchers are commonly interested in large ecological effects. However, the power to detect a large effect size depends not only on sample size but, importantly, also on between-population variability. By means of a hypothetical example, I show here that the statistical power is little affected by small-medium variance changes between populations. However, power decreases abruptly beyond a certain threshold, which I identify roughly around a five-fold difference in variance between populations. Hence, researchers should explore variance profiles of their study populations to make sure beforehand that their study populations lies within the safe zone to use the 'n = 30 rule of thumb'. Otherwise, sample size should be increased beyond 30, even to detect large effect sizes. © 2014 Museu de Ciències Naturals de Barcelona.Peer Reviewe

Stick Supply to Nests by Cliff-Nesting Raptors as an Evolutionary Load of Past Tree-Nesting

[Abstract] The supply of sticks to cliff nests by many European raptors has been explained only as a functional means of decreasing ectoparasite loads in nests and for signalling nest occupancy. We provide here a historical explanation of this behaviour as we consider it represents an evolutionary load of formerly tree-nesting species. Basically, from this perspective, facultative tree/cliff-nesting species reproduce the nests they used to build originally on top of trees, but on cliffs. Facultative species (likely evolved in forested areas) that supply their cliff nests with sticks include Pandion haliaetus, Haliaetus albicilla, Milvus migrans, Circaetus gallicus, Buteo buteo, Aquila fasciata, A. pennata, A. chrysaetos, A. heliaca, Gypaetus barbatus Gyps fulvus and Neophron percnopterus. On the contrary, the only Falco species that solely nests in cliffs (F. eleonorae)) and does not supply its nests with sticks and should be considered a true cliff-nester, likely evolved in non-forested areas. All other Falco species that do not supply their cliff nests with sticks but can make use of tree nests made by other non-raptorial species, should also be considered as true cliff-nesters, likely evolved in more forested areas or times. Milvus milvus, Elanus caeruleus, Accipiter nisus, A. gentilis, Pernis apivorus, Aquila adalberti, A. clanga, A. pomarina and Aegypius monachus are true tree nesters, likely evolved in forested areas, which did not evolve the plasticity to nest directly on cliffs.Xunta de Galicia; GRC2014/05

Subjectivism as an unavoidable feature of ecological statistics

© 2014 Museu de Ciències Naturals de Barcelona. Subjectivism as an unavoidable feature of ecological statistics.— We approach here the handling of previous information when performing statistical inference in ecology, both when dealing with model specification and selection, and when dealing with parameter estimation. We compare the perspectives of this problem from the frequentist and Bayesian schools, including objective and subjective Bayesians. We show that the issue of making use of previous information and making a priori decisions is not only a reality for Bayesians but also for frequentists. However, the latter tend to overlook this because of the common difficulty of having previous information available on the magnitude of the effect that is thought to be biologically relevant. This prior information should be fed into a priori power tests when looking for the necessary sample sizes to couple statistical and biological significances. Ecologists should make a greater effort to make use of available prior information because this is their most legitimate contribution to the inferential process. Parameter estimation and model selection would benefit if this was done, allowing a more reliable accumulation of knowledge, and hence progress, in the biological sciences.Peer Reviewe

Increasing Wild Boar Density Explains the Decline of a Montagu’s Harrier Population on a Protected Coastal Wetland

[Abstract] We studied the rapid decline in the number of breeding pairs (geometric growth rate λ = 0.86; 14 % annual decrease) of a semi–colonial ground–nesting bird of prey, the Montagu's harrier (Circus pygargus), after twelve years of rapid population growth (λ = 1.15; 15 % rate of annual increase) in a protected coastal wetland in Eastern Spain. The study was conducted from 1992–2017, and the range of values in population size was: 2–37 breeding pairs. We contrasted 20 biologically–sound hypotheses (including local and regional factors) to explain the trend over time in the annual number of pairs. The most parsimonious model included a surrogate of wild boar (Sus scrofa) density in the region during the previous year and the annual number of Montagu's harrier pairs breeding inland in the study province during the focal year. Syntopic western marsh harriers (C. aeruginosus) were not found to have any effect on the numbers of Montagu's harriers either in our modelling or when we performed a quantitative and qualitative study both for years t and t–1. Our final 'best' models did not include spring rainfall, regional forest fires or local land use changes. The impact of wild boars on breeding success, together with conspecific attraction, could have resulted in the dispersal of coastal wetland birds to larger populations in dense inland shrub lands where levels of wild boar nest predation were more likely lower.[Resumen] Hemos estudiado el rápido descenso del número de parejas reproductoras (tasa de crecimiento geométrico λ = 0,86; 14 % de disminución anual) de un ave semicolonial que nidifica en el suelo, el aguilucho cenizo (Circus pygargus), tras 12 años de rápido crecimiento demográfico (λ = 1,15; 15 % de tasa de aumento anual) en un humedal costero protegido situado en el este de España. El periodo de estudio fue 1992–2017, con un intervalo de valores del tamaño de población de 2–37 parejas reproductoras. Hemos contrastado 20 hipótesis razonables desde el punto de vista biológico (teniendo en cuenta factores locales y regionales) para explicar la tendencia del número anual de parejas. El modelo más parsimonioso incluyó un indicador de la densidad regional del jabalí (Sus scrofa) durante el año anterior y el número anual de parejas de aguilucho cenizo que se reprodujeron en el interior de la provincia del estudio, durante el año en cuestión. En nuestro modelo no se observó que el aguilucho lagunero occidental (C. aeruginosus) sintópico tuviera efecto alguno en el número de aguiluchos cenizos; tampoco lo tuvo en los análisis cuantitativos y cualitativos relativos a los años t y t–1. Las precipitaciones de primavera, los incendios forestales en la región y los cambios en el uso del suelo a escala local tampoco aparecieron en nuestros mejores modelos finales. Los efectos de jabalíes en el éxito reproductor, junto con la atracción de individuos conespecíficos, podrían haber provocado la dispersión de las aves de los humedales costeros a poblaciones más numerosas presentes en zonas arbustivas de interior, donde probablemente la depredación de nidos por jabalí sea inferior.Xunta de Galicia; GRC2014/050Xunta de Galicia; ED431C 2018/5

Prevalence of blood parasites in two western-Mediterranean local populations of the yellow-legged Gull Larus cachinnans michahellis

This study is the contribution #3 to the LIFE-NATURE program BA 3200/98/447 >Conservation of island SPAs in the Valencian Region> financed by the Generalitat Valenciana and the E.U.Peer Reviewe

Translocation in Relict Shy-Selected Animal Populations: Program Success Versus Prevention of Wildlife-Human Conflict

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Past human persecution of wildlife has acted as a major selection agent shaping many animal features including behaviour. A major component of behaviour with diverse consequences for conservation is the shyness/boldness continuum. Shyer individuals are often geographically restricted, less prone to wander out of their ecological refuges but, on the contrary, less likely to experience human-induced mortality and lead to human-wildlife conflict. In this essay we discuss how the success of translocations may interact both positively and negatively with animal personalities, based on several case studies of re-introductions and reinforcements involving remnant mammal and bird populations. Although shyness may be inconvenient to conservationists when dealing with raptor translocations in which eventual dispersal may be a desired trait in the long run, a trade-off may emerge between boldness and prevention of human-wildlife conflict when dealing with large carnivores. Some other trade-offs may also occur, such as that between boldness and desired philopatry at the initial stage of re-introductions.AMA was funded by Xunta de Galicia, project ED431C 2018/57Xunta de Galicia; ED431C 2018/5

A comparison of two methods to estimate breeding productivity in a colonial ground-nesting gull Larus cachinnans

We compared two methods commonly used to estimate breeding productivity of ground-nesting gulls: mark-recapture of ringed chicks and counts of flocks of fledglings resting at sea. Counts of the number of nests were also recorded to estimate productivity as average number of fledglings per breeding pair. Our field study was done at two locations at the western Mediterranean (Columbretes and Benidorm Islands) where small and isolated colonies of Yellow-legged Gulls (Larus cachinnans michahellis) occur. Estimates derived from direct counts were assumed to be relatively unbiased because of the small size of the study islands. We found that mark-recapture provided accurate results (similar to those obtained by counting flocks) only when mortality of chicks between capture and counts was low. Whenever both methods are applicable we recommend using flock counts to estimate productivity because it requires less input from the researcher and has little or no disturbance cost for the gulls.This study is the contribution 9 to the LIFE-NATURE program BA 3200/98/447 “Conservation of island Special Protection Areas in the Valencian Region” financed by the Generalitat Valenciana and the E.U.Peer Reviewe