Adult Apparent Survival Research Articles

A non‐invasive genetic approach for estimating the apparent survival rate of a long‐lived territorial raptor: a case study on the Golden Eagle Aquila chrysaetos

For long‐lived species, adult survival is the parameter that theoretically has the strongest impact on population dynamics; this makes its estimate crucial for conservation management. The use of non‐invasive genetic approaches coupled with capture–recapture methods is being used increasingly to estimate adult survival. Despite being regularly employed in mammals, it has been little‐used in birds and notably in long‐lived territorial species. This study aimed to determine if feathers obtained from eagle nests could be used to estimate the adult apparent survival rate and the costs associated with such an approach. Feather samples (n = 180) were collected in nests (n = 78) and directly from individual Golden Eagles (n = 36) Aquila chrysaetos in France and were genotyped using 17 microsatellite markers. The genotyping error rates obtained were low, with 3% amplification failures, 3.1% dropouts and 1.7% false alleles. The genetic variability of the markers was high, with a probability of identity between siblings of 6.8 × 10−6, allowing reliable individual identification. Of the feathers collected in nests, 90% were from breeding females; this allowed apparent survival to be estimated for adult females at a reasonable cost. The genotyping of three feathers collected from a nest ensured individual identification of the breeding female with near certainty. Our simulations showed that monitoring of at least 20 pairs over 5 years, or 10 pairs over 10 years is necessary to detect a 10% absolute decrease in adult apparent survival. Estimating the adult survival rate of long‐lived birds using feathers collected in nests is possible. A substantial budget, albeit one that is likely to be lower than that for a common capture–recapture survey, would be needed to obtain precise survival estimates.

Synchrony in adult survival is remarkably strong among common temperate songbirds across France.

Synchronous variation in demographic parameters across species increases the risk of simultaneous local extinction, which lowers the probability of subsequent recolonization. Synchrony therefore tends to destabilize meta-populations and meta-communities. Quantifying interspecific synchrony in demographic parameters, like abundance, survival, or reproduction, is thus a way to indirectly assess the stability of meta-populations and meta-communities. Moreover, it is particularly informative to identify environmental drivers of interspecific synchrony because those drivers are important across species. Using a Bayesian hierarchical multisite multispecies mark-recapture model, we investigated temporal interspecific synchrony in annual adult apparent survival for 16 common songbird species across France for the period 2001-2016. Annual adult survival was largely synchronous among species (73%, 95% credible interval [47%-94%] of the variation among years was common to all species), despite species differing in ecological niche and life history. This result was robust to different model formulations, uneven species sample sizes, and removing the long-term trend in survival. Synchrony was also shared across migratory strategies, which suggests that environmental forcing during the 4-month temperate breeding season has a large-scale, interspecific impact on songbird survival. However, the strong interspecific synchrony was not easily explained by a set of candidate weather variables we defined a priori. Spring weather variables explained only 1.4% [0.01%-5.5%] of synchrony, while the contribution of large-scale winter weather indices may have been stronger but uncertain, accounting for 12% [0.3%-37%] of synchrony. Future research could jointly model interspecific variation and covariation in breeding success, age-dependent survival, and age-dependent dispersal to understand when interspecific synchrony in abundance emerges and destabilizes meta-communities.

Annual variation of adult survival of a south-temperate House Wren population in Argentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics. Despite numerous studies on this subject in north-temperate environments, there is a lack of equivalent studies at similar latitudes in the south. Here, we used a 14-year dataset of capture, banding, and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens (Troglodytes aedon bonariae). We evaluated temporal variation in survival and the effect of environmental (climatic) and demographic variables (adult abundance, total number of fledglings produced during each breeding season) on survival estimators. We found that the probability of adult survival decreased as the abundance of breeding adults increased. This density-dependent effect could be related to the resident lifestyle of southern House Wrens, which could determine an intense competition for territories and resources that ultimately would affect their survival.

High adult survival in a northern Eurasian Curlew (Numenius arquata) population

Wetland birds such as waders are in decline across Europe. Information on demography is vital for assessing the causes of population declines, but estimates are needed from multiple populations and time periods. We used capture-recapture data from 2013–2022 including 134 individuals to estimate sex-specific apparent adult survival of Eurasian Curlews from a population breeding on agricultural fields in Finland, a stronghold region for this species in Europe. Using the Cormack–Jolly–Seber-model that considers the recapture probability of individuals, we estimated apparent survival of adults to be 0.89 (SE 0.03) for males and 0.92 (SE 0.03) for females. Our estimates of adult survival are slightly higher than those previously estimated from Fennoscandian breeding grounds in 1980s–1990s (0.82–0.88). Thus, our results suggest that adult survival of populations breeding in northern Europe has not declined during the last decades. Our study supports the view that changes in reproductive success is the main cause of decline in the Eurasian Curlew populations.

High pathogenicity avian influenza (H5N1) in Northern Gannets (Morus bassanus): Global spread, clinical signs and demographic consequences

During 2021 and 2022 High Pathogenicity Avian Influenza (HPAI) killed thousands of wild birds across Europe and North America, suggesting a change in infection dynamics and a shift to new hosts, including seabirds. Northern Gannets Morus bassanus appeared to be especially severely impacted, but a detailed account of the data available is required to help understand how the HPAI virus (HPAIV) spread across the meta‐population, and the ensuing demographic consequences. Accordingly, we analyse information on confirmed and suspected HPAIV outbreaks across most North Atlantic Gannet colonies and, for the largest colony (Bass Rock, UK), provide impacts on population size, breeding success, and preliminary results on apparent adult survival and serology. Unusually high numbers of dead Gannets were first noted at colonies in Iceland during April 2022. Outbreaks in May occurred in many Scottish colonies, followed by colonies in Canada, Germany and Norway. By the end of June, outbreaks had occurred in colonies in Canada and the English Channel. Outbreaks in 12 UK and Ireland colonies appeared to follow a clockwise pattern with the last infected colonies recorded in late August/September. Unusually high mortality was recorded at 40 colonies (75% of global total colonies). Dead birds testing positive for HPAIV H5N1 were associated with 58% of these colonies. At Bass Rock, the number of occupied nest‐sites decreased by at least 71%, breeding success declined by c. 66% compared with the long‐term UK mean and the resighting of marked individuals suggested that apparent adult survival between 2021 and 2022 could have been substantially lower than the preceding 10‐year average. Serological investigation detected antibodies specific to H5 in apparently healthy birds, indicating that some Gannets recover from HPAIV infection. Further, most of these recovered birds had black irises, suggestive of a phenotypic indicator of previous infection. Untangling the impacts of HPAIV infection from other challenges faced by seabirds is key to establishing effective conservation strategies for threatened seabird populations as the likelihood of further epizootics increases, due to increasing habitat loss and the industrialization of poultry production.

Apparent adult annual survival and population trends of Black Oystercatcher (Haematopus bachmani) breeding in British Columbia, Canada

Apparent adult annual survival and population trends of Black Oystercatcher (Haematopus bachmani) breeding in British Columbia, Canada

Consistent apparent adult survival and nest‐site fidelity of whimbrelNumenius phaeopusnear Churchill, Manitoba, Canada over a 40 year period

Reliable estimates of adult survival for many shorebird species are lacking. We used Cormack–Jolly–Seber (CJS) methods to provide an estimate of apparent, or local, survival (φ) of a population of whimbrels,Numenius phaeopus, breeding in the subarctic Churchill, Manitoba region. We used data collected in two time‐periods: 1973–1976 and 2010–2014. We also quantified nest‐site fidelity in 2010–2014 to provide context to our apparent survival estimates because mark‐recapture analyses cannot distinguish between mortality and permanent emigration. The most parsimonious CJS model did not include effects of sex or time on apparent adult survival in either period (φ = 0.76 ± 0.13 SE; φ = 0.75 ± 0.04 SE, 1973–1976 and 2010–2014, respectively). Additionally, observations of marked whimbrels between 2010 and 2019 (n = 124) showed that 61 of the 105 marked individuals (58.1%) were resighted. These estimates of return rates are, as expected, much lower than estimates of apparent survival. The median year‐to‐year distance between nests (n = 139) in 2010 to 2014 was 198 m ± 88 SE and did not differ significantly (p = 0.84) between females (x̄ = 721.9 m ± 119.8 SE) and males (x̄ = 720.3 m ± 83.1 SE). If our apparent survival estimate is indicative of true survivorship, then adult mortality during the non‐breeding season has remained constant over the last five decades, implying that the recent decline in whimbrel populations may stem largely from reduced fecundity, including egg or juvenile survival, rather than primarily from reduced adult survival.

Survival fluctuation is linked to precipitation variation during staging in a migratory shorebird

Understanding how weather conditions affect animal populations is essential to foresee population changes in times of global climate shifts. However, assessing year-round weather impacts on demographic parameters is hampered in migratory animals due to often unknown occurrence in space and time. We addressed this by coupling tracking and weather data to explain extensive variation in apparent survival across 19 years in a northern European population of little ringed plovers (Charadrius dubius). Over 90% (n = 21) of tracked individuals followed migration routes along the Indo-European flyway to south India. Building on capture–recapture histories of nearly 1400 individuals, we found that between-year variation in precipitation during post-breeding staging in northern South Asia explained 47% of variation in apparent adult survival. Overall, the intensity of the monsoon in South Asia explained 31–33% of variability in apparent survival. In contrast, weather conditions in breeding, final non-breeding and pre-breeding quarters appeared less important in this species. The integration of multi-source data seems essential for identifying key regions and periods limiting population growth, for forecasting future changes and targeting conservation efforts.

Demographic declines over time and variable responses of breeding bird populations to human footprint in the Athabasca Oil Sands Region, Alberta, Canada

Abstract Habitat loss and disturbance from industrial resource development may be contributing to declines in boreal bird populations. We applied hierarchical multi-species models to data from 31 bird species at 38 Monitoring Avian Productivity and Survivorship (MAPS) stations to assess 10-year (2011–2020) demographic trends and responses to energy sector disturbance (human footprint proportion) in the Athabasca oil sands region of Alberta, Canada. Adult captures, productivity, and residency probability all declined over the study period, and adult apparent survival probability also tended to decline. Consistent with the hypothesis that habitat loss may be driving declines, trends in adult captures, productivity, and survival were all more negative at stations with larger increases in disturbance over the study period. Species associated with early seral stages were more commonly captured at more disturbed stations, while species typical of mature forests were more commonly captured at less disturbed stations. Productivity was positively correlated with disturbance within 5-km of stations after controlling for disturbance within 1-km of stations, suggesting the importance of earlier successional habitat for post-fledging birds in the larger landscape. Adult apparent survival showed relatively little response to disturbance; stresses experienced beyond the breeding grounds likely play a larger role in influencing survival. Residency probability was negatively related to disturbance within 1-km scale of stations and could reflect processes affecting the ability of birds to establish or maintain territories in disturbed landscapes. We conclude that successional habitats that result from natural regeneration or restoration in disturbed areas, as well as decreased future footprint through recovery of mature forests and limiting of new disturbances, will both be important components of efforts to reverse population declines and maintain bird populations in the region.

No detectable effect of geolocator deployment on the short‐ or long‐term apparent survival of a tropical seabird

A wide range of biologging devices are now commonly deployed to study the movement ecology of birds, but deployment of these devices is not without its potential risks and negative impacts on the welfare, behaviour and fitness of tagged individuals. However, empirical evidence for the effects of tags is equivocal. Global location sensing (GLS) loggers are small, light level recording devices that are well suited to studying the large‐scale migratory movements of many birds. However, few published studies have examined their impact on adult survival, a key demographic rate for long‐lived species, such as seabirds. To address this, we have collated a long‐term mark–recapture dataset in conjunction with a 10‐year GLS tagging programme and examined the impact of tarsus‐mounted GLS loggers on the adult apparent survival probabilities of a medium‐sized tropical gadfly petrel. We found no evidence to indicate that deployment of GLS loggers affected apparent adult survival probabilities either in the short term, i.e. during deployment, or in the long term, i.e. from carrying a device at some point in the past. Annual adult apparent survival was estimated at 0.965 (95% CI 0.962–0.968) during 1993–2018. Our findings suggest that using GLS loggers to document the movements of medium‐sized gadfly petrels over multiple years is a viable technique without negatively impacting adult survival. This result has potential relevance to movement ecology studies of other ecologically and morphologically similar seabirds through GLS logger deployments.

Seasonal trends in adult apparent survival and reproductive trade-offs reveal potential constraints to earlier nesting in a migratory bird.

Birds aim to optimize resources for feeding young and self-maintenance by timing reproduction to coincide with peak food availability. When reproduction is mistimed, birds could incur costs that affect their survival. We studied whether nesting phenology correlated with the apparent survival of American kestrels (Falco sparverius) from two distinct populations and examined trends in clutch-initiation dates. We estimated apparent survival using multi-state mark-recapture models with nesting timing, nesting success, sex, age, and weather covariates. Nesting timing predicted the apparent survival of successful adults; however, the effect differed between populations. Early nesting kestrels had higher apparent survival than later nesters in the western population, where kestrels have a relatively long nesting season. At the eastern site, where kestrels have a relatively short nesting season, the pattern was reversed-later nesters had higher apparent survival than earlier nesters. Nesting timing did not affect the apparent survival of adults with failed nests suggesting that the energetic cost of producing fledglings contributed to the timing effect. Finally, clutch-initiation dates advanced in the western population and remained static in the eastern population. Given that both populations have seasonal declines in productivity, population-specific survival patterns provide insight into seasonal trade-offs. Specifically, nesting timing effects on survival paralleled productivity declines in the western population and inverse patterns of survival and reproduction in the eastern population suggest a condition-dependent trade-off. Concomitant seasonal declines in reproduction and survival may facilitate population-level responses to earlier springs, whereas seasonal trade-offs may constrain phenology shifts and increase vulnerability to mismatch.

Abundance and effect of health status on apparent survival of Guiana dolphins, Sotalia guianensis, in an open embayment in north‐eastern Brazil

Abstract Guiana dolphins (Sotalia guianensis) inhabit shallow waters of the tropical western Atlantic, an area that is now mostly occupied by cities and harbours. Demographic studies have been concentrated in sheltered areas of south/south‐eastern Brazil. This study investigated site fidelity and estimated population abundance and apparent survival of Guiana dolphins in Mucuripe Embayment (ME), on the north‐eastern Brazilian coast, through photo‐identification surveys and closed and open population mark–recapture models, from October 2009 to September 2011. Forty‐six Guiana dolphin groups were recorded (in groups of between one and eight dolphins, with a mean ± SD of 3.49 ± 2.33) in 27 out of 40 surveys. Twenty‐five animals were photo‐identified, with eight considered to have a ‘poor health’ status. The standardized site fidelity index (SSFI) was low (0.25). Using the program capture, the time and heterogeneity model (Mth) resulted in a total abundance estimate of 39, with a Coefficient of Variation (CV) of 21% (95% CI 35–80%). In program mark, model averaging resulted in a total abundance estimate of 33 (CV 32%, 95% CI 30–100%). Using a CV of 21%, the power to detect a decline of 50% during the study period was 0.44 and the power to detect a decline of 5% a year was 0.11. To detect these declines with a 0.90 power, 12 years of monitoring would be necessary. The annual adult apparent survival rate was low (0.71; CV 19%; 95% CI 0.40–0.90), and differed for dolphins in ‘good’ (0.64; CV 28%, 95% CI 0.27–0.89) and ‘poor’ (0.85; CV 22%; 95% CI: 0.23–0.99) health. The low abundance of Guiana dolphins in ME indicates that conservation actions should start immediately, such as creating a marine protected area, continuing awareness campaigns, using by‐catch reduction technologies, developing new regulations, and promoting law enforcement. Monitoring studies must continue with increased effort to reduce uncertainty in estimates and to improve the power to detect trends of decline.

Coping with seasonality: dynamics of adult body mass and survival in an alpine hibernator

Alpine mammals are highly vulnerable to current and projected climate change because they are confined to a certain elevation range. Physiological and behavioural adaptations in burrowing species, such as finding shelter in burrows when the summer conditions are unfavorable and hibernating in winter during the stressful period of resource shortage, could partly buffer the negative impacts of these forecasted changes. We studied the links between environmental factors and annual variations in adult mass and survival over 14 years in hoary marmots. We hypothesized that annual variation in seasonal environmental factors determines individual mass and survival through direct effects on food quality and availability, expecting greater survival when marmots reach higher mass before hibernation. We found that harsh winters decreased mass at emergence from hibernation by 47% compared with mild winters. Nonetheless, adult marmots had a greater mass gain in summers following harsh winters and reached a similar mass at the end of the summer compared with summers following mild winters. This suggests individuals can adopt a resource allocation strategy that allows maximizing summer mass gain to survive hibernation. Earlier springs also increased summer mass gain by 15 g day−1, and tended to increase apparent adult survival by 23%, compared with late springs. While these findings suggest a warming climate could have positive effects on summer mass gain and survival, survival also tended to decrease by 24% in summers with more precipitation. This suggests the forecasted changes in precipitation extremes could also trigger considerable negative effects on the demography of burrowing species in the long term. Our study shows that, although burrowing and hibernating behaviours could buffer responses to environmental changes, these behaviours are not an indefectible shield against climate change.

Colonial breeding birds show greater annual adult apparent survival globally

Colonial breeding is a common breeding system in many avian species. Its ubiquity suggests that in the evolutionary past various benefits associated with colonial breeding often outweighed the potential costs. I have investigated the association between one fitness component, namely annual adult survival, and colonial breeding. Using a global dataset of survival probabilities (2431 survival estimates from 1170 species including 213 colonial species), I found that annual adult apparent survival was greater in colonial than in solitary breeding species in both hemispheres after including phylogeny and considering potential ecological confounders such as body mass and latitude. Excluding Procellariiformes, a clade of birds with unique features (all marine colonial species laying single‐egg clutches), did not alter the conclusions. This was also the case when excluding species living year‐long on islands, which are typically non‐colonial and long‐lived, and when excluding studies where survival estimates did not account for recapture/resighting probabilities, which might differ according to breeding system. Greater annual adult apparent survival is therefore a robust feature of colonial breeding in birds, which sheds light on the evolution of this common breeding system. Future studies are needed across species to determine whether the survival advantage of colonial breeding extends to nestlings and juveniles.

Geographic and Temporal Variation in Annual Survival of a Declining Neotropical Migrant Hummingbird (Selasphorus rufus) Under Varying Fire, Snowpack, and Climatic Conditions

Rufous hummingbirds (Selasphorus rufus) have shown consistent declines in abundance since 1970, with an acceleration in this trend starting in the mid-2000s. Demographic data is needed to isolate possible drivers. We employ mark-recapture data to calculate sex-specific adult apparent annual survival, accounting for residency probability, within the coastal and interior regions of British Columbia, Canada between 1998 and 2017. For the coastal region, we also examine associations between apparent survival and a suite of migratory factors: the amount of recently and historically burned flyway habitat, fall moisture availability in the alpine (snowpack), and a broad-scale climate index (SOI), under the assumption that these factors are associated with food availability during a critical period of the annual cycle. We find no trend in adult apparent survival over the 20-year period, implicating changes in recruitment rather than adult survival as driving the declining trend in abundance. Interior birds of both sexes showed lower residency probability than coastal individuals suggesting interior sites captured more late northbound individuals or more early southbound individuals within the breeding period. Adult apparent annual survival was not correlated with any of the migratory variables we examined. Our findings suggest a need to focus on juvenile recruitment as a possible driver of the long-term declines in Rufous Hummingbirds. Future studies should consider both potential threats to productivity on the breeding grounds and to juvenile survival on the non-breeding grounds.

Population and sex-specific survival estimates for Atlantic sturgeon: addressing detection probability and tag loss

Survival estimates of animal populations provide managers with critical information on productivity, population stability, and demography. Telemetry-based survival estimates can be obtained remotely. The Atlantic sturgeon Acipenser oxyrinchus oxyrinchus is a wide-ranging species whose populations overlap along the East Coast of North America, complicating survival estimation. The objective of this study was to estimate apparent annual survival of the York River population using a Cormack-Jolly-Seber model. In this study, 36 males and 24 females were telemetered and monitored between 2013 and 2019. We considered the fit of a variety of models, selecting the best fit using Akaike’s information criterion. The optimal model estimated survival in seasonal increments and detection probability by sex in monthly increments. Five transmitters failed to leave the river and another 3 stopped being detected within 21 mo, but of those, recapturing fish confirmed 2 had been lost and 3 were technological failures (12.8% of 39 recaptured). Apparent adult annual survival was estimated to be 99.2% (95% CL: 97.9-99.7%). Addressing sex-specific detection probability and failed transmitters while including a length covariate for each individual produced higher survival estimates than previously reported studies of Atlantic sturgeon. Four males and one female appear to have died, with the location of last detection for 4 of the suspected mortalities in shipping channels near the mouth of the Chesapeake Bay, suggesting managers should focus on this area of increased risk. Such high survival estimates of the adult stage suggest Atlantic sturgeon survival may be more similar to other long-lived, late-maturing animal species than to most other short-lived fish species.

Exceptionally high apparent adult survival in three tropical species of plovers in Madagascar

Adult survival is a key component of population dynamics, and understanding variation in and the drivers of adult survival rates and longevity is critical for ecological and evolutionary studies, as well as for conservation biology and practice. Tropical species of landbirds are often selected to have higher adult survival due to high nest predation rates, but it is unclear if the same patterns occur in other avian lineages with different life history strategies. Here, we investigate adult survival of three sympatrically breeding species of shorebirds in south‐west Madagascar: the endemic and endangered Madagascar plover Charadrius thoracicus and two more widely distributed African species: the white‐fronted plover C. marginatus and the Kittlitz's plover C. pecuarius. Using mark–recapture data from 1843 individuals breeding at an intensely monitored saltmarsh over a 13‐year period, we estimated annual rates of apparent survival (φ) corrected for encounter probability. Adult apparent survival rates were high for all three species (mean ± SE): Madagascar (φ = 0.899 ± 0.010) and white‐fronted plovers (φ = 0.923 ± 0.008). Kittlitz's plovers showed a difference between the first (φ1 = 0.719 ± 0.026) and subsequent transitions (φ2+ = 0.892 ± 0.014), suggesting that transient breeders are common in this species. For birds first captured as adults, these survival estimates translate to life expectancies of 9.72 (±1.11) years in Kittlitz's plovers, 9.36 (±0.98) years in Madagascar plovers and 12.48 (±1.32) in white‐fronted plovers. We hypothesise that a long lifespan could be an adaptation arising from the unique climatic pressures on the island of Madagascar that would otherwise lead to reduced fitness. However, long lifespans may not sufficiently compensate for a reduction in breeding opportunities due to possible climatic disruption in the future. Consequently, at least two of these plover species seem vulnerable to ongoing habitat destruction and changing climate cycles.

Integrating regional and site-level data to assess drivers of population decline in a threatened aerial insectivorous bird

Knowledge of demographic processes is essential for understanding population dynamics and developing appropriate conservation strategies under global change. However, it is often challenging to collect the necessary population and demographic data to understand population dynamics. Integrated population modeling (IPM) provides an opportunity to combine population survey and demographic data from different sources. We developed an IPM and applied it to jointly analyze 15 years (2004–2018) of regional North American Breeding Bird Survey and site-level capture-recapture and age-ratio data for a barn swallow (Hirundo rustica) population in Ontario, Canada. We aimed to identify key demographic parameters and tested hypothesized environmental drivers to understand population declines of this species. Our results showed that the study population had declined by about 2% annually during our study period, which was mainly contributed by changes in net immigration and adult apparent survival. In particular, low net immigration in a few years of our study period seemed to be the main reason of population decline. Furthermore, we found that warmer temperatures in April when barn swallows return to breeding grounds had a positive effect on adult survival, while warmer temperatures during the breeding period in May–June had a negative effect on productivity. Our results indicate vulnerability of the species to inclement weather during the breeding season, suggesting potential population recovery by adopting conservation strategies that buffer climatic threats. Moreover, our IPM provides a foundation for future monitoring programs that intend to combine and maximize the utility of large-scale population counts and fine-scale demographic data.

Flocking in birds increases annual adult survival in a global analysis.

Adaptive hypotheses for the evolution of group foraging in animals typically invoke enhanced foraging efficiency and reduced predation risk. Net benefits of group foraging in different species should translate into a survival advantage for group members. Despite numerous interspecific studies in birds and mammals, few have documented a survival advantage for group foraging species. Using a large dataset in birds (> 1100 species worldwide), I investigated whether annual adult apparent survival was higher in species that forage in flocks than in solitary species. Using a phylogenetic framework to account for relatedness among species and controlling for known correlates of adult survival in birds such as body size, clutch size, latitude, and diet, I documented a positive effect of flocking on annual adult apparent survival. The increase in survival was less pronounced in occasionally flocking species suggesting that the benefits of group foraging can depend on the frequency of its use. The results highlight how group foraging can increase fitness in animals.

Monitoring Avian Productivity and Survivorship (MAPS) Programin Fukushima, Japan (2018 to 2020)

Monitoring Avian Productivity and Survivorship (MAPS) is a method developed in North America to monitor local avian fauna by constant-effort mist netting and banding during breeding seasons across years. Following the protocol of MAPS, we have been studying avian fauna in Fukushima, Japan since 2012. Here, we report the results obtained from 2018 to 2020. Also, results including adult abundance index, productivity index, and apparent adult survival rate from the entire study period (2012–2020) were analyzed. Adult abundance of the Japanese Bush Warbler Cettia diphone at a study site in Minami-Soma City were relatively stable. At a study site in Iitate Village however, adult abundance of this species fluctuated greatly. Adult abundance of the Oriental Reed Warbler Acrocephalus orientalis in Minami-Soma has been increasing steadily during the study years while that of the Oriental Greenfinch Chloris sinica has increased in the later years (2018–2020). Adult survival of the Oriental Reed Warbler from 2012–2013 to 2018–2019 in Minami-Soma was 0.15–0.40 (mean=0.26).