Climate Matching Drives Spread Rate but Not Establishment Success in Recent Unintentional Bird Introductions

Understanding factors driving successful invasions is one of the cornerstones of invasion biology. Bird invasions have been frequently used as study models, and the foundation of current knowledge largely relies on species purposefully introduced during the 19th and early 20th centuries in countries colonized by Europeans. However, the profile of exotic bird species has changed radically in the last decades, as birds are now mostly introduced into the invasion process through unplanned releases from the worldwide pet and avicultural trade. Here we assessed the role of the three main drivers of invasion success (i.e., event-, species-, and location-level factors) on the establishment and spatial spread of exotic birds using an unprecedented dataset recorded throughout the last 100 y in the Iberian Peninsula. Our multimodel inference phylogenetic approach showed that the barriers that need to be overcome by a species to successfully establish or spread are not the same. Whereas establishment is largely related to event-level factors, apparently stochastic features of the introduction (time since first introduction and propagule pressure) and to the origin of introduced species (wild-caught species show higher invasiveness than captive-bred ones), the spread across the invaded region seems to be determined by the extent to which climatic conditions in the new region resemble those of the species’ native range. Overall, these results contrast with what we learned from successful deliberate introductions and highlight that different management interventions should apply at different invasion stages, the most efficient strategies being related to event-level factors

Can Establishment Success Be Determined through Demographic Parameters? A Case Study on Five Introduced Bird Species

The dominant criterion to determine when an introduced species is established relies on the maintenance of a self-sustaining population in the area of introduction, i.e. on the viability of the population from a demographic perspective. There is however a paucity of demographic studies on introduced species, and establishment success is thus generally determined by expert opinion without undertaking population viability analyses (PVAs). By means of an intensive five year capture-recapture monitoring program (involving \u3e12,000 marked individuals) we studied the demography of five introduced passerine bird species in southern Spain which are established and have undergone a fast expansion over the last decades. We obtained useful estimates of demographic parameters (survival and reproduction) for one colonial species (Ploceus melanocephalus), confirming the long-term viability of its local population through PVAs. However, extremely low recapture rates prevented the estimation of survival parameters and population growth rates for widely distributed species with low local densities (Estrilda troglodytes and Amandava amandava) but also for highly abundant yet non-colonial species (Estrilda astrild and Euplectes afer). Therefore, determining the establishment success of introduced passerine species by demographic criteria alone may often be troublesome even when devoting much effort to field-work. Alternative quantitative methodologies such as the analysis of spatio-temporal species distributions complemented with expert opinion deserve thus their role in the assessment of establishment success of introduced species when estimates of demographic parameters are difficult to obtain, as is generally the case for non-colonial, highly mobile passerines

Borehole image techniques applied to identification of chert and dolomite layers in lacustrine sediments

Geophysical logging tools, particularly ultrasonic acoustic borehole image techniques, are applied on two different wells (CP1 and CP2) to identify and characterize the lacustrine interval (40m) of the Camp dels Ninots maardiatreme infill (Pliocene, Catalan Coastal Ranges). The CP1 well was cored and also geophysical logs and oriented borehole images were acquired. CP2 hole was partially cored but logging (geophysics and borehole images) was fully undertaken. Continuous core recovery in CP1 is compared with oriented images and is further used to identify and characterize highly reflective signals in a section of CP2 borehole that was not cored. These signals are related to silicified zones and belong to discontinuous centimetric chert nodules, while indurated massive carbonates are characterized as intervals of continuous reflectance. Despite opal nodules (chert) can be relatively small, they have a distinctive response in the ultrasonic borehole images.Peer Reviewe

Low tortoise abundances in pine forest plantations in forest-shrubland transition areas

The Spanish Ministry of Science and European Regional Development Fund funded this work through Projects CGL2012-33536 and CGL2015- 64144; MINECIO/FEDER. Regional Government of the Community of Valencia supported R.R-C. by a postgraduate grant (ACIF/2010/133) and E.G. by a postdoctoral grant (APOSTD/2015/048).In the transition between Mediterranean forest and the arid subtropical shrublands of the southeastern Iberian Peninsula, humans have transformed habitat since ancient times. Understanding the role of the original mosaic landscapes in wildlife species and the effects of the current changes as pine forest plantations, performed even outside the forest ecological boundaries, are important conservation issues. We studied variation in the density of the endangered spur-thighed tortoise (Testudo graeca) in three areas that include the four most common land types within the species’ range (pine forests, natural shrubs, dryland crop fields, and abandoned crop fields). Tortoise densities were estimated using a two-stage modeling approach with line transect distance sampling. Densities in dryland crop fields, abandoned crop fields and natural shrubs were higher (>6 individuals/ha) than in pine forests (1.25 individuals/ha). We also found large variation in density in the pine forests. Recent pine plantations showed higher densities than mature pine forests where shrub and herbaceous cover was taller and thicker. We hypothesize that mature pine forest might constrain tortoise activity by acting as partial barriers to movements. This issue is relevant for management purposes given that large areas in the tortoise’s range have recently been converted to pine plantations.Publisher PDFPeer reviewe

Sperm storage reduces the strength of the mate‐finding Allee effect

Mate searching is a key component of sexual reproduction that can have important implications for population viability, especially for the mate‐finding Allee effect. Interannual sperm storage by females may be an adaptation that potentially attenuates mate limitation, but the demographic consequences of this functional trait have not been studied. Our goal is to assess the effect of female sperm storage durability on the strength of the mate‐finding Allee effect and the viability of populations subject to low population density and habitat alteration. We used an individual‐based simulation model that incorporates realistic representations of the demographic and spatial processes of our model species, the spur‐thighed tortoise (Testudo graeca). This allowed for a detailed assessment of reproductive rates, population growth rates, and extinction probabilities. We also studied the relationship between the number of reproductive males and the reproductive rates for scenarios combining different levels of sperm storage durability, initial population density, and landscape alteration. Our results showed that simulated populations parameterized with the field‐observed demographic rates collapsed for short sperm storage durability, but were viable for a durability of one year or longer. In contrast, the simulated populations with a low initial density were only viable in human‐altered landscapes for sperm storage durability of 4 years. We find that sperm storage is an effective mechanism that can reduce the strength of the mate‐finding Allee effect and contribute to the persistence of low‐density populations. Our study highlights the key role of sperm storage in the dynamics of species with limited movement ability to facilitate reproduction in patchy landscapes or during population expansion. This study represents the first quantification of the effect of sperm storage durability on population dynamics in different landscapes and population scenarios.Financial support was granted by the Spanish Ministry of Economy, Industry and Competitiveness, and by the European Regional Development Fund (Projects CGL2012-33536, CGL2015-64144; MINECO/FEDER, UE). M.V.J.F. was supported by a “Juan de la Cierva-formación” postdoctoral grant of the Spanish Ministry of Economy and Competitiveness (reference JCI-2015-23508), a José Castillejo travel fund (reference CAS17/00225) from the Spanish Ministry of Education, Culture and Sport and a postdoctoral grant funded by the Regional Valencian Government and the European Social Fund (APOSTD/2018/043). A.S.A. was supported by a Vicenç Mut contract co-funded by the Regional Government of the Balearic Islands and the European Social Fund (PD/003/2016). A.S.A and J.D.A were supported by a Ramón y Cajal contracts (RYC-2017-22796 and RYC-2017-22783 respectively) co-funded by the Spanish Ministry of Science, Innovation and Universities, the State Research Agency and the European Social Fund. E.G. was supported by the Regional Valencian Government with a postdoctoral grant (APOSTD/2015/048)

One scute ring per year in Testudo graeca? A novel method to identify ring deposition patterns in tortoises

A reliable estimation of individuals’ age is helpful to conduct demographic studies on wildlife populations. In tortoises, many studies have estimated individuals’ age by counting growth rings on their scutes, assuming one ring per year (1:1 ratio). However, the accuracy of this method is controversial. The ring deposition pattern can vary depending on species, or even populations, and should be studied comprehensively. We studied the ring deposition pattern of Testudo graeca in southeastern Iberian Peninsula, using recaptures of 156 individuals between 2004 and 2010. We used a novel approach to explore the ring deposition pattern and to test possible differences between localities and individuals. Our results revealed that most analysed individuals (57.4%) showed a 1:1 ratio, in which rings were deposited during months of activity (spring to autumn). However, we found a trend to count less rings than years, which underestimated 1 year every 3 or 4 years. No differences in the deposition patterns were found among sites, sizes or sexes because the halt in growth during hibernation equally affects all tortoises in all sites. Our results support that the assumed 1:1 ratio in the assignment of individuals’ age is too simplistic. Since ring deposition patterns are complex, the use of statistical approaches capable of handling deviations from the assumed deposition ratios can help to better depict population age structures

Raymond Gibson (1938–2023): in memoriam

On 29 January 2023, Raymond (Ray) Gibson (Fig. 1), Professor Emeritus of Liverpool John Moores University, died in a hospital on the Wirral. He lived a very busy life, rich in travels and scientific discoveries, and he was one of the most authoritative world experts in the taxonomy of nemerteans. Ray was born on 23 November 1938 in Catterick Village in Yorkshire. He gained his Private Pilot’s License aged 17 and had several adventures in the small plane. In 1965 after leaving the Royal Airforce as a qualified pilot he got his B.Sc. in Zoology First class degree from Leeds University and in 1968 gained his Ph.D. from Leeds University. Ray began his interest in nemerteans when he was a student at Leeds University. His Ph.D. supervisor was Dr. Joe Jennings, who at the time was researching the nutrition and digestion of nemerteans and “turbellarians” (a grade of free-living platyhelminths). Ray’s first articles on the nutrition and biology of Malacobdella grossa were published when he was at Leeds University (Gibson 1967, 1968; Gibson & Jennings 1969). In 1971 Ray joined the Liverpool Regional College of Technology (this became Liverpool Polytechnic and then Liverpool John Moores University), where he worked for 30 years. His first book (Gibson 1972) is an excellent summary of knowledge on nemertean biology at the time and has ‘entangled’ (rather than ‘hooked’) young students worldwide in the following generations into this field. Ray’s exploratory enthusiasm was unmatched. He would come early in the morning and spend the day in concentrated writing, microscopy, or figure preparation. An ashtray was ever present next to his microscope and cigarettes and black coffee were all he needed to sustain him through the long days. For a long time, the histology unit was complete with the all-pervasive smell of xylene. He supervised post-graduates from many countries and backgrounds, teaching them the intricacies of paraffin sectioning and histochemistry.Peer reviewe

A survey of recent introduction events, spread and mitigation efforts of mynas (Acridotheres sp.) in Spain and Portugal

Un estudio sobre los recientes episodios de introducción, la propagación y las iniciativas de mitigación de los minás (Acridotheres sp.) en España y Portugal.— El miná común, Acridotheres tristis, está catalogado entre las 100 especies más invasoras del mundo. En el presente artículo combinamos las observaciones ya existentes con un estudio de campo para determinar los procesos de invasión de tres especies de minás en España y Portugal. Los resultados sugieren que hubo al menos 22 introducciones accidentales e independientes desde comienzos de los años 90 en la península ibérica y en tres archipiélagos. Si bien el miná oscuro (A. ginginianus) no ha llegado a establecerse, hay poblaciones reproductoras de miná común en cuatro islas. Las iniciativas de erradicación permitieron eliminar esas poblaciones insulares, pero la especie se mantiene en el estuario del Tajo (Portugal). En esta región existe también una población reproductora de miná crestado (A. cristatellus), que ha crecido exponencialmente en la última década. Es necesario combinar las campañas de erradicación con acciones preventivas, cuyo objetivo sea detener el comercio de estas especies en Europa, para evitar nuevas introducciones accidentalesPeer reviewe