The effect of climate change on avian offspring production: A global meta-analysis.

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to reproductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young.

Eggshell texture but not odor treatment affects model egg rejection in American robins (Turdus migratorius).

To curb fitness costs associated with obligate avian brood parasitism, some hosts have evolved to reject foreign eggs in the nest. American robins (Turdus migratorius) are among the few hosts of the brown-headed cowbird (Molothrus ater) that mostly remove parasitic eggs from their nests. With the parasite's eggs looking nothing like their own, American robins likely rely most on visual cues when making rejection decisions. However, we still know little about the roles that tactile and olfactory cues play in robin's or other rejecter hosts' rejection decisions. Here, we conducted a set of experiments to test for the use of tactile or olfactory cues in egg rejection by robins. For the tactile experiment, we found that robins were more likely to reject rough rather than smooth eggs. However, our tactile model egg design was not able to fully discriminate between tactile and visual sensory modalities. In the olfaction experiment, we did not find a significant effect of egg scent treatment on rejection rates. Accordingly, future studies on egg rejection should attempt to fully distinguish between tactile and visual cues, as well as examine olfactory cues in other egg rejecter host species.

The effect of avian brood parasitism on physiological responses of host nestlings.

Avian obligate brood parasites lay their eggs in the nests of other species that may provide care for the foreign offspring. Brood parasitism often imparts substantial fitness losses upon host nestlings when they are raised alongside the typically more competitive, larger, and older parasitic chick(s). Whereas fitness costs due to reduced host offspring survival in parasitized broods have been studied in detail, the physiological changes in host nestlings caused by parasitic nestmate(s) are less well known. We compared prothonotary warbler (Protonotaria citrea) nestlings, a host of the nest-sharing brown-headed cowbird (Molothrus ater), in experimentally parasitized vs. non-parasitized broods. Our aim was to determine whether cohabitation with brood parasitic young impacted host nestling baseline corticosterone plasma concentrations, immune responses, body condition, and mortality. Corticosterone levels and body condition of host nestlings were similar between nests with or without a cowbird nestmate, whereas host immune responses were lower and nestling mortality was greater in parasitized broods, irrespective of variation in brood size or total brood mass. We detected no trade-offs of baseline corticosterone levels with either immune responses or with body condition. These results suggest that this host species' nestlings experience some adverse fitness-relevant physiological effects in parasitized broods, but are also resilient in other aspects when coping with brood parasitism.

Physiological responses of host parents to rearing an avian brood parasite: An experimental study.

Raising an obligate avian brood parasite is costly for host parents because it redirects valuable parental resources from one's own offspring to genetically unrelated young. The costs of raising a brood parasite may be mediated by physiological stressors for foster parents if it requires greater or biased parental effort compared to raising non-parasitized broods. For example, upregulating glucocorticoid hormones or reducing immune responses may mediate a trade-off between resource allocation to a current brood versus future reproductive opportunities, but published data on parasitized hosts' physiology are scarce. Here we used an experimental approach to test if host parents respond to the presence of brood parasitic young through dynamic changes in their own physiology. We conducted our experiments with parasitic brown-headed cowbirds (Molothrus ater) fostered into nests of host prothonotary warblers (Protonotaria citrea). Relative to parents caring for non-parasitized control broods, parasitism increased baseline corticosterone levels and reduced body mass in adult male, but not in female, hosts. Immune responses to a novel antigen were depressed in both parents of parasitized broods compared to parents of non-parasitized broods. Additionally, we found that immune function increased along the breeding season regardless of treatment. These experiments also confirmed prior observational data that parasitized adult males have reduced return rates to breeding sites in years subsequent to raising cowbirds. The findings demonstrate diverse physiological effects of parasitism on the foster parents in our particular host-brood parasite system, yet we found no evidence of individual trade-offs between endocrine and immune responses of adult hosts.

Incidence of stroke among Saudi population: a systematic review and meta-analysis.

BACKGROUND AND AIMS: Stroke is a leading cause of death and disability worldwide. However, our knowledge of the incidence of stroke for Saudi Arabian population is not known. Thus, we aimed to determine the pooled annual incidence of stroke in Saudi Arabia. We conducted a comprehensive literature search of PubMed, Web of Science, and SCOPUS, without language or publication year limits. Outcomes of interest were stroke incidence rate for both first and recurrent. A total of five studies met the inclusion criteria for this review. The pooled annual incidence of stroke in Saudi Arabia was 0.029% (95% CI: 0.015 to 0.047) equivalent of 29 strokes per 100,000 people annually (95% CI: 15 to 47). CONCLUSION: The findings indicate that there are 29 stroke cases for every 100,000 people annually for individuals residing Saudi Arabia. Our values were lower than those of other high-income countries. Establishing a nationwide stroke registry is warranted for monitoring and improving healthcare services provided to stroke survivors.

Greater opportunities for sexual selection in male than in female obligate brood parasitic birds.

Females are expected to have evolved to be more discriminatory in mate choice than males as a result of greater reproductive investment into larger gametes (eggs vs. sperm). In turn, males are predicted to be more promiscuous than females, showing both a larger variance in the number of mates and a greater increase in reproductive success with more mates, yielding more intense sexual selection on males vs. females (Bateman's Paradigm). However, sex differences in costly parental care strategies can either reinforce or counteract the initial asymmetry in reproductive investment, which may be one cause for some studies failing to conform with predictions of Bateman's Paradigm. For example, in many bird species with small female-biased initial investment but extensive biparental care, both sexes should be subject to similar strengths of sexual selection because males and females are similarly restricted in their ability to pursue additional mates. Unlike 99% of avian species, however, obligate brood parasitic birds lack any parental care in either sex, predicting a conformation to Bateman's Paradigm. Here we use microsatellite genotyping to demonstrate that in brood parasitic brown-headed cowbirds (Molothrus ater), per capita annual reproductive success increases with the number of mates in males, but not in females. Furthermore, also as predicted, the variance of the number of mates and offspring is greater in males than in females. Thus, contrary to previous findings in this species, our results conform to predictions of the Bateman's Paradigm for taxa without parental care.

ClinVar: public archive of interpretations of clinically relevant variants.

ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/) at the National Center for Biotechnology Information (NCBI) is a freely available archive for interpretations of clinical significance of variants for reported conditions. The database includes germline and somatic variants of any size, type or genomic location. Interpretations are submitted by clinical testing laboratories, research laboratories, locus-specific databases, OMIM®, GeneReviews™, UniProt, expert panels and practice guidelines. In NCBI's Variation submission portal, submitters upload batch submissions or use the Submission Wizard for single submissions. Each submitted interpretation is assigned an accession number prefixed with SCV. ClinVar staff review validation reports with data types such as HGVS (Human Genome Variation Society) expressions; however, clinical significance is reported directly from submitters. Interpretations are aggregated by variant-condition combination and assigned an accession number prefixed with RCV. Clinical significance is calculated for the aggregate record, indicating consensus or conflict in the submitted interpretations. ClinVar uses data standards, such as HGVS nomenclature for variants and MedGen identifiers for conditions. The data are available on the web as variant-specific views; the entire data set can be downloaded via ftp. Programmatic access for ClinVar records is available through NCBI's E-utilities. Future development includes providing a variant-centric XML archive and a web page for details of SCV submissions.

A generalist brood parasite modifies use of a host in response to reproductive success.

Avian obligate brood parasites, which rely solely on hosts to raise their young, should choose the highest quality hosts to maximize reproductive output. Brown-headed cowbirds (Molothrus ater) are extreme host generalists, yet female cowbirds could use information based on past reproductive outcomes to make egg-laying decisions thus minimizing fitness costs associated with parasitizing low-quality hosts. We use a long-term (21 years) nest-box study of a single host, the prothonotary warbler (Protonotaria citrea), to show that local cowbird reproductive success, but not host reproductive success, was positively correlated with the probability of parasitism the following year. Experimental manipulations of cowbird success corroborated that female cowbirds make future decisions about which hosts to use based on information pertaining to past cowbird success, both within and between years. The within-year pattern, in particular, points to local cowbird females selecting hosts based on past reproductive outcomes. This, coupled with high site fidelity of female cowbirds between years, points to information use, rather than cowbird natal returns alone, increasing parasitism rates on highly productive sites between years.

Effect of neurturin deficiency on cholinergic and catecholaminergic innervation of the murine eye.

Neurturin (NRTN) is a neurotrophic factor required for the development of many parasympathetic neurons and normal cholinergic innervation of the heart, lacrimal glands and numerous other tissues. Previous studies with transgenic mouse models showed that NRTN is also essential for normal development and function of the retina (J. Neurosci. 28:4123-4135, 2008). NRTN knockout (KO) mice exhibit a marked thinning of the outer plexiform layer (OPL) of the retina, with reduced abundance of horizontal cell dendrites and axons, and aberrant projections of horizontal cells and bipolar cells into the outer nuclear layer. The effects of NRTN deletion on specific neurotransmitter systems in the retina and on cholinergic innervation of the iris are unknown. To begin addressing this deficiency, we used immunohistochemical methods to study cholinergic and noradrenergic innervation of the iris and the presence and localization of cholinergic and dopaminergic neurons and nerve fibers in eyes from adult male wild-type (WT) and NRTN KO mice (age 4-6 months). Mice were euthanized, and eyes were removed and fixed in cold neutral buffered formalin or 4% paraformaldehyde. Formalin-fixed eyes were embedded in paraffin, and 5 µm cross-sections were collected. Representative sections were stained with hematoxylin and eosin or processed for fluorescence immunohistochemistry after treatment for antigen retrieval. Whole mount preparations were dissected from paraformaldehyde fixed eyes and used for immunohistochemistry. Cholinergic and catecholaminergic nerve fibers were labeled with primary antibodies to the vesicular acetylcholine transporter (VAChT) and tyrosine hydroxylase (TH), respectively. Cholinergic and dopaminergic cell bodies were labeled with antibodies to choline acetyltransferase (ChAT) and TH, respectively. Cholinergic innervation of the mouse iris was restricted to the sphincter region, and noradrenergic fibers occurred throughout the iris and in the ciliary processes. This pattern was unaffected by deletion of NRTN. Furthermore, functional experiments demonstrated that cholinergic regulation of the pupil diameter was retained in NRTN KO mice. Hematoxylin and eosin stains of the retina confirmed a marked thinning of the OPL in KO mice. VAChT and ChAT staining of the retina revealed two bands of cholinergic processes in the inner plexiform layer, and these were unaffected by NRTN deletion. Likewise, NRTN deletion did not affect the abundance of ChAT-positive ganglion and amacrine cells. In marked contrast, staining for TH showed an increased abundance of dopaminergic processes in the OPL of retina from KO mice. Staining of retinal whole mounts for TH showed no difference in the abundance of dopaminergic amacrine cells between WT and KO mice. These findings demonstrate that the neurotrophic factor NRTN is not required for the development or maintenance of cholinergic innervation of the iris, cholinergic control of pupil diameter, or for development of cholinergic and dopaminergic amacrine cells of the retina. However, NRTN deficiency causes a marked reduction in the size of the OPL and aberrant growth of dopaminergic processes into this region.

Host learning selects for the coevolution of greater egg mimicry and narrower antiparasitic egg-rejection thresholds.

Egg rejection is an effective and widespread antiparasitic defense to eliminate foreign eggs from the nests of hosts of brood parasitic birds. Several lines of observational and critical experimental evidence support a role for learning by hosts in the recognition of parasitic versus own eggs; specifically, individual hosts that have had prior or current experience with brood parasitism are more likely to reject foreign eggs. Here we confirm experimentally the role of prior experience in altering subsequent egg-rejection decisions in the American robin Turdus migratorius, a free-living host species of an obligate brood parasite, the brown-headed cowbird Molothrus ater. We then model the coevolutionary trajectory of both the extent of mimicry of host eggs by parasitic eggs and the host's egg rejection thresholds in response to an increasing role of learning in egg recognition. Critically, with more learning, we see the evolution of both narrower (more discriminating) rejection thresholds in hosts and greater egg mimicry in parasites. Increasing host clutch size (number of eggs/nest) and increasing parasite load (parasitism rate) also have narrowing effects on the egg-rejection threshold. Together, these results suggest that learning from prior experience with egg rejection may play an important role in the coevolution of egg-mimetic lineages of brood parasites and the refined egg rejection defenses of hosts.

The limits of egg recognition: testing acceptance thresholds of American robins in response to decreasingly egg-shaped objects in the nest.

Some hosts of avian brood parasites reduce or eliminate the costs of parasitism by removing foreign eggs from the nest (rejecter hosts). In turn, even acceptor hosts typically remove most non-egg-shaped objects from the nest, including broken shells, fallen leaves and other detritus. In search for the evolutionary origins and sensory mechanisms of egg rejection, we assessed where the potential threshold between egg recognition and nest hygiene may lie when it comes to stimulus shape. Most previous studies applied comparisons of egg-sized objects with non-continuous variation in shape. Here, instead, we used two series of three-dimensional-printed objects, designed a priori to increasingly diverge from natural eggs along two axes (width or angularity) of shape variation. As predicted, we detected transitions from mostly acceptance to mostly rejection in the nests of American robins Turdus migratorius along each of the two axes. Our methods parallel previous innovations in egg-rejection studies through the use of continuous variation in egg coloration and maculation contrast, to better understand the sensory limits and thresholds of variation in egg recognition and rejection in diverse hosts of avian brood parasites.

Brood Parasites Are a Heterogeneous and Functionally Distinct Class of Natural Enemies.

Brood parasitism is the introduction of unrelated progeny into the nest or colony of a host that then raises the foreign young. This reproductive strategy has evolved independently and repeatedly among diverse animal taxa, and brood parasite-host interactions have become models for understanding coevolutionary arms races. Yet brood parasites have remained largely overlooked in previous syntheses of natural enemy ecology. Here, we argue that brood parasites are a heterogeneous and versatile class of natural enemies, blending traits characteristic of predators and trophic parasites. The functional distinctness of brood parasites reinforces the idea that natural enemies exist along a continuum rather than as a dichotomy. Brood parasite-host interactions can serve as valuable case studies to unify parasite-host and predator-prey theories.

Using Digital Image Analysis to Quantify Small Arthropod Vectors.

Quantifying arthropod vectors can be a time-consuming process. Here, we describe a technique to count large samples of small arthropods using ImageJ. ImageJ is an open source image processing software, produced by the National Institutes of Health, with a straightforward interface that has proven useful in quantifying small organisms (i.e., cells, pollen, eggs). In 2017, we deployed CDC light traps baited with carbon dioxide among seven sites to capture black flies (Diptera: Simuliidae). Samples of the captured specimens were photographed, and then quantified manually and automatically, using ImageJ. We compared the accuracy of three types of automated counts to manual counts of black flies using an information-theoretic approach. We found that changing the particle size produced counts closest to those obtained by manual counts. Even over a large range of values, from tens to thousands of flies, our automated counts were often identical to and almost always within 5% of the manual counts. When different, automated counts were usually slightly less than manual counts, and thus conservative estimates. This automated technique is simple, repeatable, requires minimal training, and can reduce the time needed to quantify small arthropods such as black flies.

Test-Retest Reliability of activPAL in Measuring Sedentary Behavior and Physical Activity in People With Type 2 Diabetes.

BACKGROUND: To investigate how changes in sedentary behavior relate to health outcomes, it is important to establish the test-retest reliability of activity monitors in measuring habitual sedentary behavior in people with type 2 diabetes (T2D) as a prerequisite for interpreting this information. Thus, the authors' objective was to examine the test-retest reliability of a common activity monitor (activPAL™) in measuring sedentary behavior and physical activity in people with T2D. METHODS: Sedentary-time, standing-time, stepping-time, step-count, and sit-to-stand transitions were obtained from two 7-day assessment periods separated by at least 1 week. Test-retest reliability was determined with the intraclass correlation coefficient (ICC) to compare sedentary and activity measures between the 2 time points. RESULTS: A total of 30 participants with self-reported T2D completed the study (age 65 [6] y, 63% women, body mass index 33.3 [5] kg/m2). High test-retest reliability was found for sedentary-time (ICC = .79; 95% confidence interval [CI], .61-.89) and standing-time (ICC = .74; 95% CI, .53-.87). Very high test-retest reliability was found for stepping-time (ICC = .90; 95% CI, .81-.95), step-count (ICC = .91; 95% CI, .83-.96), and sit-to-stand transitions (ICC = .90; 95% CI, .79-.95). CONCLUSION: The activPAL™ device showed high to very high test-retest reliability in measuring all tested activity categories in people with T2D.

A comparison of diabetes self-care behavior in people with type 2 diabetes with and without insomnia symptoms.

AIMS: Individuals with type 2 diabetes (T2DM) are advised to undertake diabetes self-care behavior (DSCB) in order to avoid complications of T2DM. However, comorbidities, such as insomnia symptoms which are commonly reported in people with T2DM, may limit the ability to engage in DSCB. Insomnia and the common sequelae accompanying insomnia such as pain, depression, and anxiety may negatively influence the performance of DSCB. Therefore, this study aimed to compare the DSCB of people with T2DM with and without insomnia symptoms. METHODS: Sixty participants with T2DM were divided into two groups based on the presence of insomnia symptoms: T2DM-only group and T2DM+ insomnia group. Insomnia symptoms were identified using the Insomnia Severity Index (ISI). DSCB was assessed using the Diabetic Care Profile (DCP). A standardized composite score was established to account for all of the DCP domains. Chi-square and independent sample t tests were used to assess between-group differences in categorical and continuous variables, respectively. Stepwise linear regression analysis used the ISI score to predict standardized DCP composite score, while controlling for covariates. RESULTS: Significant between-group differences were found in age, symptoms of pain, depression, and anxiety. The total DCP composite score was significantly lower in the T2DM+ insomnia group compared to the T2DM-only group (- 0.30 ± 0.46 vs. 0.36 ± 0.48, respectively, p < 0.001) with large effect size (g = 1.40). Stepwise linear regression results showed that a 1-point increase in ISI score significantly predicted a .03-point decrease in standardized DCP composite score, after controlling for age, symptoms of pain, depression, and anxiety (ß = - 0.03, p = 0.04). CONCLUSIONS: The data suggest that people with T2DM and insomnia symptoms had worse scores on the majority of the DSCB domains and a worse DCP composite score compared to people with T2DM only. The data suggest a negative association between insomnia severity and DSCB among people with T2DM. Further research using a larger sample size and more rigorous research design is required to examine the causal relationship between insomnia symptoms and DSCB.

Prevalence of falls among older adults in the Gulf Cooperation Council countries: A systematic review and meta-analysis.

AIM: The aim of this study was to conduct a systematic review and meta-analysis for studies that have examined the prevalence and risk factors of falls in older adults living in the Gulf Cooperation Council countries (GCC). METHODS: A literature search was performed using PubMed, Web of Science, Physiotherapy Evidence Database; and SCOPUS up to October 2018 to identify studies that have examined prevalence, risk factors, or consequences of falls in older adults living in the GCC. RESULTS: A total of 6 studies met the inclusion criteria. The pooled prevalence of falls among older adults residing in GCC countries was 46.9%. Falls among included studies were associated with older age, female gender, low educational level, and number of medications. CONCLUSIONS: The study shows a high prevalence of falls in older adults living in the GCC countries. The risk factors in the current study must be interpreted with caution, since some of the included studies did not report any risk factors. Due to the limited number of evidence evaluating risk factors and consequences of falls in the GCC countries population, a further longitudinal research is needed.

Effect of Cognitive Behavioral Therapy for Insomnia on Insomnia Symptoms for Individuals With Type 2 Diabetes: Protocol for a Pilot Randomized Controlled Trial.

BACKGROUND: Insomnia symptoms are a common form of sleep difficulty among people with type 2 diabetes (T2D) affecting sleep quality and health outcomes. Several interventional approaches have been used to improve sleep outcomes in people with T2D. Nonpharmacological approaches, such as cognitive behavioral therapy for insomnia (CBT-I), show promising results regarding safety and sustainability of improvements, although CBT-I has not been examined in people with T2D. Promoting sleep for people with insomnia and T2D could improve insomnia severity and diabetes outcomes. OBJECTIVE: The objective of this study is to establish a protocol for a pilot randomized controlled trial (RCT) to examine the effect of 6 sessions of CBT-I on insomnia severity (primary outcome), sleep variability, and other health-related outcomes in individuals with T2D and insomnia symptoms. METHODS: This RCT will use random mixed block size randomization with stratification to assign 28 participants with T2D and insomnia symptoms to either a CBT-I group or a health education group. Outcomes including insomnia severity; sleep variability; diabetes self-care behavior (DSCB); glycemic control (A1c); glucose level; sleep quality; daytime sleepiness; and symptoms of depression, anxiety, and pain will be gathered before and after the 6-week intervention. Chi-square and independent t tests will be used to test for between-group differences at baseline. Independent t tests will be used to examine the effect of the CBT-I intervention on change score means for insomnia severity, sleep variability, DSCB, A1c, fatigue, sleep quality, daytime sleepiness, and severity of depression, anxiety, and pain. For all analyses, alpha level will be set at .05. RESULTS: This study recruitment began in February 2019 and was completed in September 2019. CONCLUSIONS: The intervention, including 6 sessions of CBT-I, will provide insight about its effect in improving insomnia symptoms, sleep variability, fatigue, and diabetes-related health outcomes in people with T2D and those with insomnia symptoms when compared with control. TRIAL REGISTRATION: ClinicalTrials.gov NCT03713996; https://clinicaltrials.gov/ct2/show/NCT03713996. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/14647.

The Effect of T'ai Chi Exercise on Lipid Profiles: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.

BACKGROUND: Cardiovascular disease is a common health problem resulting from many factors, including dyslipidemia. T'ai chi is one of the interventions assigned to improve lipid profiles and other physical outcomes. However, conflicting results might be attributed to different study designs and interventional approaches. A systematic review and meta-analysis are needed to evaluate existing evidence. OBJECTIVE: The aim of this systematic review and meta-analysis is to evaluate existing randomized clinical trials (RCTs) regarding the overall effect of t'ai chi exercise on lipid profiles. METHODS: Electronic databases (MEDLINE and Cumulative Index to Nursing and Allied Health Literature) were searched. The authors included only English peer reviewed published RCTs that used a t'ai chi intervention and high-density lipoprotein cholesterol (HDL-C) as the primary outcome along with low-density lipoprotein cholesterol (LDL-C) and/or total cholesterol (TC) as secondary outcomes. RESULTS: The authors identified 37 potentially eligible studies. Only eight RCTs were eligible for their qualitative review, and seven studies were eligible for meta-analysis. The included studies were rated as having a low risk of bias. Despite the overall low risk of bias, all studies failed to blind participants to group assignment and were generally unclear about whether they were selectively reporting data. A fixed effect model (I2 = 38.16%) demonstrated a small positive effect of t'ai chi on HDL-C (Cohen d = 0.12; standard error [SE] = 0.067; p = 0.037). A random effect model demonstrated a medium effect and small effect for LDL-C (Cohen d = 0.47; SE = 0.347; p = 0.089) and TC (Cohen d = 0.34; SE = 0.225; p = 0.066), respectively. CONCLUSION: T'ai chi may potentially be beneficial on lipid profiles across different age groups and populations. Although there were conflicting results regarding the effect of t'ai chi on lipid profiles, the majority of studies had at least a small positive effect indicating a potential positive effect of t'ai chi on HDL-C, LDL-C, and/or TC. Therefore, further research is needed to confirm the small positive effect of t'ai chi on lipid profiles found in this review.

Recruitment for exercise or physical activity interventions: a protocol for systematic review.

INTRODUCTION: Recruiting participants into research trials is essential for the advancement of scientific knowledge that depends on clinical research studies. For the field of exercise and physical activity, there is an added difficulty in recruiting participants because participants must be willing to participate in an intervention that requires a significant commitment of both time and physical effort. Therefore, we have planned a systematic review to analyse how methodological factors, intervention characteristics and participant demographics impact recruitment rates in specific populations. This information will help researchers improve the design and recruitment approach in future studies. METHODS AND ANALYSIS: A mixed methods systematic review will be performed on studies that implement physical activity interventions and present data on participant recruitment. We plan on searching the Pubmed, Cumulative Index to Nursing and Allied Health Literature and Online Resource for Recruitment research in Clinical Trials databases for potentially eligible articles from database inception through 10 February 2017. A standardised approach will be used to identify studies through a review of titles, abstracts and reference lists. The process for each eligible study is to determine their eligibility, extract data from eligible studies and rate each eligible study's methodological quality. Exploratory multivariate regression models will be used to determine the effects of methodological factors, intervention characteristics and participant demographics on the recruitment variables of interest. ETHICS AND DISSEMINATION: Because all of the data used in this systematic review has been published, this review does not require ethical approval. The results of this review will be disseminated through peer-reviewed publication as well as through conference presentations. PROSPERO REGISTRATION NUMBER: CRD42017057284.

Juvenile survival in a neotropical migratory songbird is lower than expected.

Attempts to estimate and identify factors influencing first-year survival in passerines, survival between fledging and the first reproductive attempt (i.e. juvenile survival), have largely been confounded by natal dispersal, particularly in long-distance migratory passerines. We studied Prothonotary Warblers (Protonotaria citrea) breeding in nest boxes to estimate first-year survival while accounting for biases related to dispersal that are common in mark-recapture studies. The natal dispersal distribution (median = 1420 m; n = 429) and a distance-dependent recruitment rate, which controls for effects of study site configuration, both indicated a pattern of short-distance natal dispersal. This pattern was consistent with results of a systematic survey for birds returning outside the nest box study sites (up to 30 km in all directions) within a majority (81%) of total available bottomland forest habitat, further suggesting that permanent emigration outside of the study system was rare. We used multistate mark-recapture modeling to estimate first-year survival and incorporated factors thought to influence survival while accounting for the potential confounding effects of dispersal on recapture probabilities for warblers that fledged during 2004-2009 (n = 6093). Overall, the average first-year survival for warblers reared without cowbird nestmates was 0.11 (95% CI = 0.09-0.13), decreased with fledging date (0.22 early to 0.03 late) and averaged 40% lower for warblers reared with a brood parasite nestmate. First-year survival was less than half of the rate thought to represent population replacement in migratory passerines (∼0.30). This very low rate suggests that surviving the first year of life for many Neotropical migratory species is even more difficult than previously thought, forcing us to rethink estimates used in population models.