Structural effects of reedbed grazing and its cessation on reed-nesting songbird densities

Reedbeds are crucial breeding habitats for vulnerable songbird species.Irrespective of their protection status,these habitats may be threatened by organic matter accumulation,progressively leading to structural homoge-nization and habitat succession towards woodland.Managers prevent excessive litter build-up with various in-terventions opening-up the reedbeds,such as grazing,which may be detrimental or suitable for some reed bird species.We assessed the effects of extensive grazing by horses and its cessation in the medium and long terms on reedbed structure,and the consequences on reed-nesting songbird densities in Estagnol Nature Reserve,a pro-tected wetland near the French Mediterranean coast.We compared reedbed structural features between grazed,newly ungrazed and old-ungrazed plots.During nine years,we censused four songbird species in spring and collected water level data in the same survey plots.Grazing reduced reedbed extent,rejuvenated the vegetation with more short green stems on a thinner litter,and produced higher structural heterogeneity and discontinuity compared to long-lasting non grazing.Newly ungrazed plot showed intermediate effects.All surveyed songbird total densities were similar among plots while species numbers and densities differed.Grazed reedbed was more attractive to Moustached Warblers(Acrocephalus melanopogon)and Great Reed Warblers(Acrocephalus arundi-naceus),likely due to the large edges and the high vegetation structural heterogeneity.However,Moustached Warblers were more negatively affected by higher water level in grazed reedbed,presumably because flooding prevents litter foraging.The newly ungrazed reedbed was not preferred by any species.All warbler species were found under low density in the old-ungrazed reedbed,where Reed Buntings(Emberiza schoeniclus)were exclu-sively found.Food availability related to thick litter layer may explain this predilection.Common Reed Warblers(Acrocephalus scirpaceus)were found everywhere in similar densities.We conclude that reedbed management by extensive horse grazing and also its long-term cessation may benefit several songbird species.Within a context of wetland degradation and disappearance,both management strategies are useful to establish and maintain suitable habitats for reed-nesting songbird communities.

Differential colour-ring loss among Dalmatian Pelican(Pelecanus crispus) colonies and its consequence on survival estimates

The analysis of bird ringing data often comes with some potential sources of error and bias,as ring wear and/or loss could affect mark-recapture analyses and produce erroneous estimates of survival.Furthermore,ring wear and loss rates may differ between and within species based on the habitat they use or the species’ life-history traits and behaviour as well as the type of the ring.In this study we use resighting data from a long-term double marking experiment to directly estimate the rate of colour-ring loss among different Dalmatian Pelican colonies over time,evaluate any possible factors that could contribute to differential ring loss and assess how it may bias the results of mark-resighting analyses.Based on 14,849 resightings from 1275 individuals and using multi-state continuous-time hidden Markov models(HMMs) we showed that probability of ring loss was markedly different among colonies,ranging from 0.10 to 0.42 within the first year of marking,whereas the cumulative probability of losing a ring after ten years ranged 0.64 to 0.99.These rates are among the highest estimated when compared to previous studies in waterbirds.Our approach assessing the intra-specific variance in ring loss provided several factors potentially involved,such as the use of glue and the fledgling age accuracy and we could further hypothesise the effect of environmental factors.Finally,our results showed that ring loss can be a significant challenge for the assessment of the species’ population dynamics using mark-recapture methods as survival was consistently underestimated when not accounting for ring loss and varied significantly among different colonies.

Maternal effects, malaria infections and the badge size of the house sparrow

Background: The evolution of sexual signals is not only determined by immediate sexual selection but also by selection arising from the environment and the interaction with developmental effects.In this study we aimed to investigate how the badge size of male house sparrows(Passer domesticus) is correlated to avian malaria infections as well as to prenatal testosterone exposure,measured as the 2D:4D digit ratio.The rationale behind this study is that the immunosuppressive effect of maternal testosterone deposition combined with the fitness cost imposed by parasites may cause important trade-offs to the development of secondary sexual signals.Methods: Assuming that vector abundance is a key variable associated with infection risk by avian malaria,we caught adult male sparrows from eight different populations in the Camargue,France,four of which were located in a vector-controlled area,and the other four in an untreated area.For each bird we measured its badge size,digit ratio and took blood to determine its infections status.We used PCR to identify the malaria parasite species and strain that caused the infection.Results: Contrary to our expectation,prevalence of disease did not differ across the vector-treatment regions,with around 80 % of birds being infected in both areas,and those infections were caused largely by a single strain,Plasmodium relictum SGS1.Although infected birds had a badge size not significantly different from uninfected males,there was a condition-dependent association between badge size,infection status and maternal testosterone deposition.Conclusions: This study illustrates that the complexity of temporal and ecological dimensions makes the relationships between disease,testosterone-related traits and secondary sexual signals that have been previously reported less general than thought.

A solution scan of societal options to reduce transmission and spread of respiratory viruses:SARS-CoV-2 as a case study

Societal biosecurity–measures built into everyday society to minimize risks from pests and diseases–is an important aspect of managing epidemics and pandemics.We aimed to identify societal options for reducing the transmission and spread of respiratory viruses.We used SARS-CoV-2(severe acute respiratory syndrome coronavirus 2)as a case study to meet the immediate need to manage the COVID-19 pandemic and eventually transition to more normal societal conditions,and to catalog options for managing similar pandemics in the future.We used a‘solution scanning’approach.We read the literature;consulted psychology,public health,medical,and solution scanning experts;crowd-sourced options using social media;and collated comments on a preprint.Here,we present a list of 519 possible measures to reduce SARS-CoV-2 transmission and spread.We provide a long list of options for policymakers and businesses to consider when designing biosecurity plans to combat SARS-CoV-2 and similar pathogens in the future.We also developed an online application to help with this process.We encourage testing of actions,documentation of outcomes,revisions to the current list,and the addition of further options.

Perturbation and delayed recovery of the reed invertebrate assemblage in Camargue marshes sprayed with Bacillus thuringiensis israelensis

Bacillus thuringiensis var. israelensis （Bti） is the most commonly used larvicide to control mosquitoes worldwide. Considered as nontoxic to most organisms, Bti can nevertheless cause trophic perturbations to natural communities by reducing the abundance of Chironomidae, which are a key element of wetland food webs. Since August 2006, up to 8400 of the 33 000 ha of mosquito larval biotopes in the Camargue （Rh6ne delta, in southern France）, are monitored by a public agency and Bti-sprayed （aqueous solution of VectoBac 12AS at 2.5 L/ha） whenever mosquito larvae （Ochlerotatus easpius and Oc. detritus） appeared in water bodies. This resulted in 30-50 aerial treatments/year, in addition to ground spraying of unknown frequency. The sprayed habitats include Phragmites australis reedbeds, which support a specific avifauna of conservation concern. We compared the abundance of invertebrate prey available to passerine birds at treated and control sites relative to the predicted values based on hydrology over a 9-year period. Food available to reed passerines was significantly reduced at treated areas, translating into a 34% decrease in breeding birds based on predictive modeling. The most affected arthropods were Diptera, Aranaea, Coleoptera, and Hymenoptera. No cumulative effects were observed over time, but the recovery of the invertebrate assemblage after the cessation of mosquito control was delayed due to Bti spore persistence and proliferation in the sediments. While hydrology remains a prime factor influencing primary and secondary productivity of the Camargue reed marshes, Bti spraying had significant negative effects on animal communities at several trophic levels.

Egg clutch patterning in Lestes virens （Odonata, Lestidae） with evolutionary emphasis on endophytic oviposition in lestid dragonflies

Egg deposition within plants is one of the most widely distributed and ancient behaviors in Odonata. The resulting clutch consists of eggs placed in peculiar pattern that can be a characteristic for certain groups of Odonata. Despite their importance for paleontological and evolutionary research, data on egg-clutch positioning are missing or insufficient for most species. Here, patterning of egg clutches in Lestes virens was measured and described in detail for the first time. The female usually produces a linear row of single eggs directed at an angle rightward or leftward to the longitudinal axis of plant substrate. Less often eggs are arranged in egg-sets consisting of up to 4 eggs. Apparently, the female insect follows the rigid behavior stereotypes during oviposition and is unable to easily switch to the alternate stereotypical behavior of single egg deposition or production of multiegg sets. Based on a literature review and original data, egg clutch patterning of European Lestidae is overlaid on preexisting phylogenies. The resulting evolutionary scenario of egg-clutch patterning can be considered in the framework of egg-laying behavior in Lestidae.