Arboreal birds do not avoid scattered trees in West Africa

Arboreal birds tend to remain in woody vegetation and avoid crossing open areas. Therefore, few tree-dwelling birds are to be expected in scattered trees. We tested this expectation with field data collected in the deserts, savannas and open agricultural parklands of West Africa where woody cover in 1,327 stratified random study sites varied between 0.2 and 29%. We found no evidence that scattered trees were avoided. Instead, bird density in trees was independent of trees occurring clumped or singly. The presence of birds in an individual tree was related to tree species and tree-related variables, but not to woody cover or species composition of the surrounding woody vegetation. We hypothesise that scattered trees are not avoided because (1) travel time between trees is too short to have a negative impact on foraging time, (2) predation risk of arboreal passerines is very low (bird-hunting raptors are scarce in the deserts and savannas of West Africa and mostly prey on ground-feeding, not arboreal, birds), and (3) the probability of being chased away by other arboreal birds is less when trees are more scattered. Scattered trees are ecologically important since hundreds of millions of migratory woodland birds, of which several species are in decline, spend the northern winter in Africa in open, often human-modified, landscapes where trees are well spaced

Pallid Harrier Circus macrourus helper at the nest of a Marsh Harrier C. aeruginosus

In 2022, a male Pallid Harrier was recorded in farmland in the province of Groningen on 19 June when transferring a prey to a male Marsh Harrier. This bird had been colour-ringed as a chick in a nest of Pallid Harriers in 2019, less than two km away from the harrier’s presence in 2022. The Marsh Harriers had a nest in a wheat field. The nest was observed from a hide on 7 July, when five chicks of 1-12 days old were present. Between 8:45 and 13:30, a total of 22 prey deliveries were recorded (of which 18 were brought to the nest), five by Pallid Harrier, six by female Marsh Harrier and eleven by male Marsh Harrier. Except two birds, all prey were voles, presumably Microtus arvalis. Taking prey mass into account (25 g for Common Voles, 50 g for birds), each chick received 35 g of food per 100 minutes, of which the male Pallid Harrier contributed 10.4 g (30%). Furthermore, the Pallid Harrier was also frequently recorded chasing potential predators away from the nest site, including attacks on Marsh Harriers (other than the nesting pair), Buzzards Buteo buteo, Kestrels Falco tinnunculus, Carrion Crows Corvus corone and a Goshawk Accipiter gentilis. The nest eventually fledged four chicks. It is unknown whether extrapair copulations of female Marsh and male Pallid Harrier had taken place, which might have explained the Pallid male’s investment in the Marsh Harrier brood

Repeatability in spring arrival dates in Pied Flycatchers varies among years and sexes

Timing of arrival in long-distance migration could have fitness consequences: arrival too early impairs survival chances, whereas arrival too late reduces current reproductive success. Evolution thus may have favoured a phenotype that arrived at the optimal time. However, individuals within populations of long-distance migrant species arrive over a considerable time span, and often show consistency in whether they are early or late. This repeatability in arrival varies between studies, and we hypothesise it to be affected by conditions encountered en route or in winter. Here we report on the spring arrival dates of Pied Flycatchers Ficedula hypoleuca to their Dutch breeding sites during eight consecutive years. Our field estimates of arrival were highly accurate, as validated by geolocator data on 13 individuals. Years differed in mean arrival dates. Within years and sexes, arrival date generally spanned more than two weeks. First-year individuals arrived on average 4-5 days later than older individuals. Using repeated arrival dates of more than 500 individuals we show that (1) the overall arrival repeatabilities were similar for females and males, (2) arrival repeatabilities varied temporally, with individuals in consecutive years having sometimes moderate (R = 0.2) and sometimes rather high (>0.40) repeatabilities, and (3) individual females arrived later in their first than in their second year. In females, repeatabilities of arrival and laying dates were similar. We hypothesize that individual flycatchers have a high individual consistency in their spring migration departure date from the wintering grounds. However, previous studies suggest the expression of this individual schedule to be affected by environmental circumstances at the wintering grounds or by what is encountered en route, determining whether this variation is still present at arrival on the breeding grounds. Sexes seemed to differ in this respect, as year-to-year variation in repeatabilities of timing was explained by individual consistency in females, but not in males. We discuss the relevance of the observed variation for the potential for an evolutionary response when environments change

Phase II Feasibility and Biomarker Study of Neoadjuvant Trastuzumab and Pertuzumab With Chemoradiotherapy for Resectable Human Epidermal Growth Factor Receptor 2-Positive Esophageal Adenocarcinoma:TRAP Study

PURPOSE: Approximately 15% to 43% of esophageal adenocarcinomas (EACs) are human epidermal growth factor receptor 2 (HER2) positive. Because dual-agent HER2 blockade demonstrated a survival benefit in breast cancer, we conducted a phase II feasibility study of trastuzumab and pertuzumab added to neoadjuvant chemoradiotherapy (nCRT) in patients with EAC. PATIENTS AND METHODS: Patients with resectable HER2-positive EAC received standard nCRT with carboplatin and paclitaxel and 41.4 Gy of radiotherapy, with 4 mg/kg of trastuzumab on day 1, 2 mg/kg per week during weeks 2 to 6, and 6 mg/kg per week during weeks 7, 10, and 13 and 840 mg of pertuzumab every 3 weeks. The primary end point was feasibility, defined as ≥ 80% completion of treatment with both trastuzumab and pertuzumab. An exploratory comparison of survival with a propensity score-matched cohort receiving standard nCRT was performed, as were exploratory pharmacokinetic and biomarker analyses. RESULTS: Of the 40 enrolled patients (78% men; median age, 63 years), 33 (83%) completed treatment with trastuzumab and pertuzumab. No unexpected safety events were observed. R0 resection was achieved in all patients undergoing surgery, with pathologic complete response in 13 patients (34%). Three-year progression-free and overall survival (OS) were 57% and 71%, respectively (median follow-up, 32.1 months). Compared with the propensity score-matched cohort, a significantly longer OS was observed with HER2 blockade (hazard ratio, 0.58; 95% CI, 0.34 to 0.97). Results of pharmacokinetic analysis and activity on [18F]fluorodeoxyglucose positron emission tomography scans did not correlate with survival or pathologic response. Patients with HER2 3+ overexpression or growth factor receptor-bound protein 7 (Grb7) -positive tumors at baseline demonstrated significantly better survival (P = .007) or treatment response (P = .016), respectively. CONCLUSION: Addition of trastuzumab and pertuzumab to nCRT in patients with HER2-positive EAC is feasible and demonstrates potentially promising activity compared with historical controls. HER2 3+ overexpression and Grb7 positivity are potentially predictive for survival and treatment response, respectively

Genome-Wide Identification of Ampicillin Resistance Determinants in Enterococcus faecium

Enterococcus faecium has become a nosocomial pathogen of major importance, causing infections that are difficult to treat owing to its multi-drug resistance. In particular, resistance to the β-lactam antibiotic ampicillin has become ubiquitous among clinical isolates. Mutations in the low-affinity penicillin binding protein PBP5 have previously been shown to be important for ampicillin resistance in E. faecium, but the existence of additional resistance determinants has been suggested. Here, we constructed a high-density transposon mutant library in E. faecium and developed a transposon mutant tracking approach termed Microarray-based Transposon Mapping (M-TraM), leading to the identification of a compendium of E. faecium genes that contribute to ampicillin resistance. These genes are part of the core genome of E. faecium, indicating a high potential for E. faecium to evolve towards β-lactam resistance. To validate the M-TraM results, we adapted a Cre-lox recombination system to construct targeted, markerless mutants in E. faecium. We confirmed the role of four genes in ampicillin resistance by the generation of targeted mutants and further characterized these mutants regarding their resistance to lysozyme. The results revealed that ddcP, a gene predicted to encode a low-molecular-weight penicillin binding protein with D-alanyl-D-alanine carboxypeptidase activity, was essential for high-level ampicillin resistance. Furthermore, deletion of ddcP sensitized E. faecium to lysozyme and abolished membrane-associated D,D-carboxypeptidase activity. This study has led to the development of a broadly applicable platform for functional genomic-based studies in E. faecium, and it provides a new perspective on the genetic basis of ampicillin resistance in this organism

Detection probabilities and absolute densities of birds in trees

For a study of long-distance migrants in sub-Saharan Africa, a census method was developed that combined precision and accuracy regarding bird numbers and tree choice. The number of birds present in trees and shrubs can be counted accurately, although it is time-consuming. We describe how much time is needed to detect all birds present in trees, using data collected in over 2000 plots across West Africa during the dry season (October-March in 2007-2015). The observation time per tree depended on tree size, number of birds present and the opacity of the crown. The giving-up time of the observers increased with canopy volume, but was independent of the number of birds in a tree. Detection probabilities of bird species differed relative to microhabitat choice and feeding techniques. Species-specific detectabilities hardly varied during the day or the season. All foraging birds and immobile birds (save a few percent in dense canopies) were detected using the individual-tree-approach. Bird density is expressed as number per canopy volume, but little information is lost when density is given as number per canopy surface. The variation in bird density was large and differed per tree species. Within tree species, bird density was related to the opacity of the crown, the abundance of insects and whether there were berries or flowers. These findings suggest that, to collect biologically relevant information, the density of tree-dwelling birds should be measured at the level of the individual tree, and not per surface area, habitat type or tree species (as is typical in published studies)

Mannetje Steppekiekendief Circus macrourus als helper bij het nest van een Bruine Kiekendief C. aeruginosus

In 2022, a male Pallid Harrier was recorded in farmland in the province of Groningen on 19 June when transferring a prey to a male Marsh Harrier. This bird had been colour-ringed as a chick in a nest of Pallid Harriers in 2019, less than two km away from the harrier’s presence in 2022. The Marsh Harriers had a nest in a wheat field. The nest was observed from a hide on 7 July, when five chicks of 1-12 days old were present. Between 8:45 and 13:30, a total of 22 prey deliveries were recorded (of which 18 were brought to the nest), five by Pallid Harrier, six by female Marsh Harrier and eleven by male Marsh Harrier. Except two birds, all prey were voles, presumably Microtus arvalis. Taking prey mass into account (25 g for Common Voles, 50 g for birds), each chick received 35 g of food per 100 minutes, of which the male Pallid Harrier contributed 10.4 g (30%). Furthermore, the Pallid Harrier was also frequently recorded chasing potential predators away from the nest site, including attacks on Marsh Harriers (other than the nesting pair), Buzzards Buteo buteo, Kestrels Falco tinnunculus, Carrion Crows Corvus corone and a Goshawk Accipiter gentilis. The nest eventually fledged four chicks. It is unknown whether extrapair copulations of female Marsh and male Pallid Harrier had taken place, which might have explained the Pallid male’s investment in the Marsh Harrier brood