Chick Survival Research Articles

Quantifying egg attendance behaviours of wild Asian houbara can improve artificial incubation outcomes

Artificial incubation is fundamental in ex situ avian conservation interventions for an increasing range of threatened species, but incubation parameters can differ between species. Both egg-turning angle and frequency are critical for successful embryonic development, but measuring these parameters in wild birds has historically been difficult. Using data-loggers inside artificial eggs that accurately record parental egg attendance behaviours, we quantified turning angles and rates throughout the incubation of 6 nesting wild Asian houbaras Chlamydotis macqueenii, a species bred in captivity in response to human over-exploitation. Wild females turned their eggs 0.6 times h-1 with a mean angle of 40.9° turn-1. Mimicking the patterns of wild birds (‘wild’ treatment), we applied a mean angular change of 40-50° turn once h-1 to artificially incubated eggs and compared this to eggs treated with an existing protocol (‘control’) of 120-130° per turn. Mean hatchability for the wild treatment (78.8%, n = 766) was similar to the control (76.6%, n = 1196). The wild treatment (n = 591) produced significantly heavier hatchlings (2.7%) than the control treatment (n = 893). However, chick growth rates (g d-1 and daily % mass change) and survival to Day 10 were not different between groups. The wild treatment demonstrates that turning angles affect embryo development and, perhaps, hatchability. Investigating natural incubation behaviours using egg-loggers and applying these patterns to artificial incubation appears efficacious to achieve optimal incubation protocols and reduce the need for ex situ trial and error refinement in conservation interventions of captive-bred threatened bird species.

Ecological value of different vegetated strip types in providing valuable insect-rich habitats for grey partridge chicks

The intensification and specialisation of agriculture has contributed to farmland wildlife decline, including farmland birds. Grey partridge is a farmland species which has experienced a significant decline across Europe in recent decades. Chick survival rate is a key determinant of grey partridge population change and depends essentially on the availability of insect food. In this study, ground-dwelling and canopy-dwelling insects were collected using pitfall trapping and sweep netting methodologies, respectively, on different strip types in an area established for the conservation of grey partridge. The aim was to further our understanding of the value of different vegetated strip types in providing insect-rich habitats for grey partridge chicks. Overall, wildflower strip (WS) provided the greatest insect abundance. Significantly more ground-dwelling insects were found on WS, natural regeneration (NS) and leguminous strips (LS) than on grass strip (GS). Canopy-dwelling insects were also significantly more abundant on WS compared to all other strip types. This study highlights that WSs may represent important habitats in providing insect-rich food for grey partridge chicks and sowing these strips may therefore play a key role in decreasing chick mortality and supporting grey partridge conservation. It also demonstrates that other different vegetated strip types may still provide strip-specific insect taxa, in addition to other valuable resources. This study recommends a complex mosaic of different strip types to provide key resources for grey partridge, such as insect and plant food, nesting habitats and overwinter cover.

Effect of vegetation density on survival of South African free-ranging indigenous chicken broods.

The survival of juveniles from hatching until recruitment is a critical determinant of indigenous chicken population growth under extensive free-range production systems. A longitudinal study was conducted to investigate the impact of vegetation cover on survival of indigenous chicken broods in Msinga, South Africa. Survival records of 281 chicks hatched in sparsely vegetated (SV) communal lands and 233 hatched chicks in densely vegetated (DV) resettlement areas were collected from hatch until 12weeks of age. Data on probable cause of death of individual chicks was collected using a structured checklist. Kaplan-Meir survival distributions and log rank tests were used to estimate the survival functions of broods between vegetation cover types. Logistic regression analysis was used to determine the association between management factors and mortality risk in SV and DV. Chick survival from hatching to 12weeks was higher in SV (55 ± 3.14%) than DV (41 ± 4.19%) (P < 0.05). Mean chick survival time did not differ between SV (56 ± 3.30days) and DV (49 ± 3.23days) (P > 0.05). Aerial predators were the major cause of chick mortality (over 60%) followed by terrestrial predators (30%) in both vegetation cover types. The odds of mortality were higher in DV compared to SV (P < 0.05). It was concluded that increasing vegetation cover decreases survival of scavenging chicks between hatching and end of brooding at 12weeks of age, and therefore brood management actions should ensure adequate protection of free-ranging chicken broods in densely vegetated rearing habitats.

Trophic and fitness correlates of mercury and organochlorine compound residues in egg-laying Antarctic petrels

Understanding the drivers and effects of exposure to contaminants such as mercury (Hg) and organochlorine compounds (OCs) in Antarctic wildlife is still limited. Yet, Hg and OCs have known physiological and fitness effects in animals, with consequences on their populations. Here we measured total Hg (a proxy of methyl-Hg) in blood cells and feathers, and 12 OCs (seven polychlorinated biphenyls, PCBs, and five organochlorine pesticides, OCPs) in plasma of 30 breeding female Antarctic petrels Thalassoica antarctica from one of the largest colonies in Antarctica (Svarthamaren, Dronning Maud Land). This colony is declining and there is poor documentation on the potential role played by contaminants on individual physiology and fitness. Carbon (δ13C) and nitrogen (δ15N) stable isotope values measured in the females' blood cells and feathers served as proxies of their feeding ecology during the pre-laying (austral spring) and moulting (winter) periods, respectively. We document feather Hg concentrations (mean ± SD, 2.41 ± 0.83 μg g−1 dry weight, dw) for the first time in this species. Blood cell Hg concentrations (1.38 ± 0.43 μg g−1 dw) were almost twice as high as those reported in a recent study, and increased with pre-laying trophic position (blood cell δ15N). Moulting trophic ecology did not predict blood Hg concentrations. PCB concentrations were very low (Σ7PCBs, 0.35 ± 0.31 ng g−1 wet weight, ww). Among OCPs, HCB (1.02 ± 0.36 ng g−1 ww) and p, p’-DDE (1.02 ± 1.49 ng g−1 ww) residues were comparable to those of ecologically-similar polar seabirds, while Mirex residues (0.72 ± 0.35 ng g−1 ww) were higher. PCB and OCP concentrations showed no clear relationship with pre-laying or moulting feeding ecology, indicating that other factors overcome dietary drivers. OC residues were inversely related to body condition, suggesting stronger release of OCs into the circulation of egg-laying females upon depletion of their lipid reserves. Egg volume, hatching success, chick body condition and survival were not related to maternal Hg or OC concentrations. Legacy contaminant exposure does not seem to represent a threat for the breeding fraction of this population over the short term. Yet, exposure to contaminants, especially Mirex, and other concurring environmental stressors should be monitored over the long-term in this declining population.

Birds advancing lay dates with warming springs face greater risk of chick mortality

In response to a warming planet with earlier springs, migratory animals are adjusting the timing of essential life stages. Although these adjustments may be essential for keeping pace with resource phenology, they may prove insufficient, as evidenced by population declines in many species. However, even when species can match the tempo of climate change, other consequences may emerge when exposed to novel conditions earlier in the year. Here, using three long-term datasets on bird reproduction, daily insect availability, and weather, we investigated the complex mechanisms affecting reproductive success in an aerial insectivore, the tree swallow (Tachycineta bicolor). By examining breeding records over nearly half a century, we discovered that tree swallows have continuously advanced their egg laying by ∼3 d per decade. However, earlier-hatching offspring are now exposed to inclement weather events twice as often as they were in the 1970s. Our long-term daily insect biomass dataset shows no long-term trends over 25 y but precipitous drops in flying insect numbers on days with low ambient temperatures. Insect availability has a considerable impact on chick survival: Even a single inclement weather event can reduce offspring survival by >50%. Our results highlight the multifaceted threats that climate change poses on migrating species. The decoupling between cold snap occurrence and generally warming spring temperatures can affect reproductive success and threaten long-term persistence of populations. Understanding the exact mechanisms that endanger aerial insectivores is especially timely because this guild is experiencing the steepest and most widespread declines across North America and Europe.

Mixed evidence for effects of stewardship on Least Tern reproductive success in coastal Mississippi

Abstract Disturbance from human activity can cause reduced productivity of coastal birds that nest on sandy beaches. A common method to protect coastal birds from human disturbance is the use of signs and fencing to close off a section of beach used for breeding. This management action requires public compliance and might require enforcement, such as in the use of volunteer stewards stationed at protected colonies that provide education and enforcement. I assessed the effectiveness of active stewardship as a conservation measure to protect nesting Least Terns (Sternula antillarum) in coastal Mississippi by determining if colony-level productivity (fledglings produced per nest) was correlated with stewardship effort (hours that stewards protected each colony), the rate of disturbance from human and natural sources, and additional factors. Observers surveyed 24 Least Tern colonies in Harrison County, Mississippi, twice weekly during the 2017–2019 breeding seasons to record the number of nests present, the fate of marked nests, predator tracks within the colony, and the number of fledglings produced per colony. Concurrently, during their work shifts, stewards recorded all sources and durations of disturbance events that caused the terns to flush or respond with defense. Least Tern daily nest survival increased with colony size and stewardship effort, and was lower during intervals that included weekends and evidence of owl presence. Total productivity was negatively associated with avian predator disturbance rate and the total time adults spent flushed, but was not associated with stewardship effort. The results of this study demonstrate that active stewardship can have a positive effect on Least Tern productivity by increasing nest success, whereas current stewardship practices were not sufficient to increase chick survival, even in a system with a paucity of ground predators.

Piping Plover population increase after Hurricane Sandy mediated by immigration and reproductive output

AbstractEvaluating population-level responses to conservation action following large-scale disturbance can improve the efficacy of future habitat conservation measures. In October 2012, Hurricane Sandy storm surges cleared vegetation and opened inlets through the barrier islands, Fire Island and Westhampton Island, New York, creating Piping Plover (Charadrius melodus) habitat. Storm effects prompted an island-wide stabilization project, which had the potential to negatively affect novel Piping Plover habitat. Certain sections of Fire Island were designed to create and/or improve habitat (hereafter, restoration areas) to mitigate possible habitat loss or degradation. Since Piping Plovers in New York appear to be habitat-limited, we anticipated positive population growth following habitat creation. From 2013 to 2018, we captured and banded 152 adults and 353 chicks, and monitored 279 nests and 160 broods. We developed an integrated population model to assess demographic processes in response to hurricane created-habitat (2013–2018) and the creation of restoration areas (2015–2018). We observed positive population growth in 3 of 5 yr, and overall growth throughout the period (λ¯ = 1.13). Immigration and reproductive output were correlated with population growth (r = 0.92 [95% CI: 0.22 to 0.98] and 0.84 [95% CI: –0.47 to 0.95], respectively). Compared with the rest of the study area, restoration areas had higher chick survival, and lower nest survival and after second-year site fidelity. The result was population growth in restoration areas (λ¯= 1.14) similar to the whole study area. In the short term, restoration areas seemed to mimic natural Piping Plover habitat. Vegetation removal, an important process in renewing natural Piping Plover habitat, likely will be necessary to maintain habitat suitability. Efforts to increase immigration of new breeding adults into the system, and to improve reproductive output, primarily by habitat creation or maintenance, are likely to have the greatest local effect on population growth.

An immune challenge of female great tits decreases offspring survival and has sex-specific effects on offspring body size

Investment in immunity is expected to decrease (costly immunity) or enhance (terminal investment) reproductive performance. Here, we tested the effects of activation of the immune system in female great tits (Parus major) on (1) their reproductive effort and (2) the survival and body condition of their offspring, controlling for chick sex. We injected females tending 3-day-old chicks with sheep red blood cells (SRBC) or saline (control) and recorded their provisioning rates 6 days later, during the expected peak of antibody production. We measured tarsus length and body mass in 11-day-old chicks and monitored changes in brood size. We found that female provisioning rates were unaffected by the SRBC challenge. An analysis without an outlier, however, showed a significant challenge-by-hatch date interaction. This interaction indicated that female provisioning rates decreased with hatch dates in the SRBC but not in the control nests, suggesting a stronger effect in later breeders. Chick body mass was not affected by female immunisation nor by its interaction with chick sex. However, we found a significant challenge-by-sex interaction on offspring tarsus. In SRBC nests, the difference in tarsus length between male and female chicks was lower than in controls, suggesting sex-dependent effects of the challenge on offspring structural growth. Finally, chick mortality was greater in SRBC nests compared with controls, but chick survival probability was not affected by sex. Overall, our results support the costly immunity but not the terminal investment hypothesis in the great tit.

Egg Overspray with Herbicides and Fungicides Reduces Survival of Red-Legged Partridge Chicks.

Within the environmental risk assessment conducted for pesticide registration in the European Union (EU), avian reproductive toxicity is characterized after exposing adults. However, eggs of ground-nesting species can be exposed when pesticide applications occur during laying or incubation. We simulated environmentally realistic exposure of red-legged partridge (Alectoris rufa) eggs to an herbicide (2,4-D) and a fungicide (tebuconazole) applied to winter cereal crops during the breeding season of most farmland birds. We analyzed the effects on hatching success, offspring survival, and physiology. Exposure by overspray led to greater pesticide accumulation in the eggshell or content than exposure through contact with treated soil (3.1-13.7 times higher, depending on the pesticide and target sample). Egg overspray with tebuconazole significantly increased chick mortality, which was 26% higher than that of controls. 2,4-D caused a similar but a close to significant increase (chick mortality 24% higher than controls). Exposure to either pesticide through contact with treated soils did not affect chick survival but altered some biochemical parameters posthatching. Our experiment shows that egg spraying with pesticides should be considered as a relevant exposure scenario in risk assessment procedures, given its potential to affect the reproductive success of ground-nesting farmland birds.

Survival during the pre-fledging period rather than during post-fledging drives variation in local recruitment of an endangered migratory shorebird, the Southern Dunlin Calidris alpina schinzii

The declines in wet-grassland breeding shorebird populations are considered to mainly result from changes in reproduction. While there is plenty of information on nest survival, little reliable information exists on local recruitment due to confounding effects of permanent emigration. Furthermore, few studies have been able to study the roles of pre- and post-fledging survival on local recruitment. Therefore, it is unclear whether local recruitment of young reflects conditions at the breeding sites or at non-breeding sites. We studied an isolated population of the endangered Southern Dunlin (Calidris alpina schinzii) breeding on the west coast of Sweden to examine (1) brood survival (probability of at least one chick fledging) by following broods fates and (2) local recruitment (survival from hatching to 1 year old) using capture-recapture data. We then examined how much of the annual variation in juvenile survival was explained by variation in brood survival. Brood survival was on average 0.58 (annual range 0.08–1.00) and explained 64% of variation in annual local recruitment. Still local recruitment was rather high for a shorebird (0.17, SE = 0.023), which reflects the isolated nature of the study population. Our results suggest that local recruitment seems to be mainly constrained by chick survival during the pre-fledging period. Therefore, management of breeding sites leading to increased brood survival, e.g., reducing predation on chicks, should have strong impacts on local recruitment and local population growth.

Environmental and behavioral factors affect northern bobwhite offspring survival

Many environmental and behavioral factors can affect offspring survival, and these factors can vary by species. Parental investments, defense or distraction displays, and translocation can potentially affect survival of young. Alterations in parental investment strategies may carry implications for population growth due to lower offspring survival in translocated bobwhites. We hypothesized that translocation would not impact brood defense behaviors in bobwhites as predator communities may be similar between donor sites (Florida) and release sites (North Carolina). However, we hypothesized that brood defense behaviors affect offspring survival rates. We conducted defense behavior observations by approaching brood‐rearing bobwhites and recording exhibited behaviors, and assigned scores based on behavioral intensity. We used the corral capture method and modified‐suture technique to capture and radio‐tag bobwhite chicks. Brood defense behaviors did not differ between resident and translocated bobwhites. We observed seven different brood defense behaviors: fly away, run, labored flight, labored flight with broken wing display, run with broken wing display, hold tight and approach behaviors. We found that time‐varying precipitation and behavioral intensity affected bobwhite chick survival. These results indicate that translocation does not impact brood defense behaviors due to behavioral similarities between resident and translocated cohorts. These results portend that some variation in annual chick mortality cannot be mitigated by habitat management. We also provide evidence that translocation does not alter/suppress important behavioral patterns in bobwhite, indicating it is a viable method for restoring bobwhite populations in conjunction with habitat management.

Sex and hatching order modulate the association between MHC-II diversity and fitness in early-life stages of a wild seabird.

Genes of the major histocompatibility complex (MHC) play a pivotal role in parasite resistance, and their allelic diversity has been associated with fitness variations in several taxa. However, studies report inconsistencies in the direction of this association, with either positive, quadratic or no association being described. These discrepancies may arise because the fitness costs and benefits of MHC diversity differ among individuals depending on their exposure and immune responses to parasites. Here, we investigated in black-legged kittiwake (Rissa tridactyla) chicks whether associations between MHC class-II diversity and fitness vary with sex and hatching order. MHC-II diversity was positively associated with growth and tick clearance in female chicks, but not in male chicks. Our data also revealed a positive association between MHC-II diversity and survival in second-hatched female chicks (two eggs being the typical clutch size). These findings may result from condition-dependent parasite infections differentially impacting sexes in relation to hatching order. We thus suggest that it may be important to account for individual heterogeneities in traits that potentially exert selective pressures on MHC diversity in order to properly predict MHC-fitness associations.

Falling out of the host nest: an overlooked factor decreasing survival of brood parasite chicks

Animals rely on an array of environmental triggers or cues to make their behavioural and life‐history decisions. Brood–parasitic females should prefer the best host to maximize their reproductive success. Despite the fact that Eurasian reed warbler Acrocephalus scirpaceus is one of the most frequent host of the common cuckoo Cuculus canorus, parasitic chicks often prematurely fall out of the nests and drown. To establish whether these events are influenced by the size of the nest, we experimentally replaced original Eurasian reed warbler nests for much bigger great reed warbler Acrocephalus arundinaceus ones and transferred cuckoo chicks into them to record their fate. The chicks in bigger nests showed significantly lower falling‐out rate (4 of 29) compared with those remained in smaller nests (12 of 32). These findings suggest that host nest size plays an important role in the suitability of host species and that smaller host nests may pose a high mortality risk to the relatively big cuckoo chicks. Moreover, cuckoo chicks that fell out of the nests were significantly less fed by foster parents before falling‐out event than those stayed in the nests. This indicates that insufficient parental care may also facilitate falling‐out of cuckoo chicks, probably because hungry chicks are more restless in host nests. The relatively frequent falling‐out events represent a substantial and underestimated cost of brood parasites. Without video surveillance it can incorrectly be confused with predation. We therefore strongly recommend using video‐recording for determining predation costs in birds.

Asymmetric benefits of a heterospecific breeding association vary with habitat, conspecific abundance and breeding stage

Heterospecific breeding associations may benefit individuals by mitigating predation risk but may also create costs if they increase competition for resources or are more easily detectable by predators. Our understanding of the interactions among hetero‐ and conspecifics is often lacking in mixed species colonies. Here, we test how the presence of hetero‐ and conspecifics influence nest and chick survival for two listed (under the U.S. Endangered Species Act) migratory species breeding on the Missouri River, USA. We monitored 2507 piping plover Charadrius melodus nests and 3245 chicks as well as 1060 least tern Sternula antillarum nests and 1374 chicks on Lake Sakakawea, the Garrison River Reach and the Gavins Point Reach for varying years between 2007 and 2016. Piping plover nest and chick survival improved with the presence and abundance of least terns, but least terns only benefited from piping plover presence for certain study areas and breeding stages. Piping plover nest survival was also improved by the presence and abundance of conspecifics on the Garrison River Reach and was negatively influenced by conspecific presence on Lake Sakakawea. Least tern chick survival improved with the presence of other least terns only on the Gavins Point Reach. Ultimately, the heterospecific breeding association between plovers and terns is mutualistic but asymmetric and is moderated by habitat, abundance of conspecifics and breeding stage. Our results highlight that spatiotemporal variation in the interactions among individuals breeding in groups precludes simple generalizations and suggests that management focused on one species may restrict benefits to that focal species if nest site requirements for heterospecifics are not also included.

Microplastics and the Impact of Plastic on Wildlife: A Literature Review

Microplastics (size <5 mm) have become an international attention since they have been discovered in wildlife and human gastro-intestinal tract, and might harm health. The objective of this paper is to review microplastics and analyze its possible impact on wildlife and seabird. Seabirds are upper-trophic level predators in marine ecosystems, feed on zooplankton, fish, and squid. Microplastics in seabirds have been reported in many countries, including the USA, Canada, Brazil, Japan, China, the Netherlands, and North Pacific region, involving albatrosses, petrels, storm-petrels, fulmars, cormorants, shearwaters, penguins, and many other seabird species. Microplastics were accidentally ingested because of their resemblance to the fish, plankton, or from ingestion of microplastics that already occurred inside fish food. Types of microplastics were pellet, fragment, film, fiber, foamed plastic and styrofoam. Microplastics might decrease feeding stimuli by producing a false sense of fullness, causing the bird to stop eating, resulting in malnutrition and death. Other harmful impact on birds are interrupting nutrient absorption, disrupting reproductive problems, and hindered growth and survival of chicks. Study on microplastics in Indonesia is in progress, by using Little-black cormorant to represent seabirds.

Analysis of Technical Efficiency of Smallholder Indigenous Chicken Keepers in Meru County, Kenya

The objective of this study was to analyze the technical efficiency of smallholder indigenous chicken keepers in Meru County of Kenya. The County lies on the Eastern side of Kenya’s Central highlands at 0 o , 38 00 o E, and covers 6936.4 Km 2 .Data were collected through a cross-sectional survey from 90 (30 Ng’onyi, 30 Ntalami and 30 Kangeta villages) randomly sampled farms using semi-structured questionnaires. Data analysis was carried out using the SPSS and Frontier 4.1 c computer softwares. Stochastic frontier production function was estimated using the maximum likelihood estimation technique. The farms were characterized and their technical efficiencies estimated. Results revealed that the indigenous chicken keeping households owned an average of 17 at a time, after selling out about 15 for incomes. They produced an average of 500 eggs per annum, with each hen producing about 45. Households consumed both eggs and chicken. The value of the sold and consumed eggs as well as sold chicken was Ksh. 17 715 (1 USD= Ksh. 107). Most household heads were married (85%), with 70% aged between 36 and 65 years. A majority of the farmers were literate (90%). Over 75% of the households had between 3 and 6 persons. The average size of land owned was 1.33 acres. It’s only 9% of farmers who were satisfied with farming. Decrease in land size prompted households to increase the flock sizes (tended towards commercialization). The number of live chickens sold correlated positively with increase in the number of indigenous chickens kept, but inversely proportional to land size owned. The study established that farmers operated at 74.83% technical efficiency implying that they could increase their flock from an average of 17 to 23 through better use of available resources, given the current state of technology without extra cost. It was recommended that since market for live indigenous chicken was in existence, approaches that assist in improving the chicken population be adopted. Use of genetically improved indigenous breeds, improvement of chicken housing, supplementing the free-range feed with concentrate feed, improving egg hatchability and chick survival, require being considered. Improving farmer knowledge through better public extension service would be a pre-requisite for increased number of indigenous chicken flock size.

On-farm comparative evaluation of Solomon hay-box brooder and Mekete bamboo brooders at Basketo Special District, Southern Ethiopia

The study was conducted in two peasant associations (ZabaEla and GezaAyima) and in one city administration (laska) at Basketo special district of SNNPR, Ethiopia. The objective of this study was to compare Solomon hay-box brooder with Mekete bamboo brooder for growth and production performances of day-old chickens. Ten randomly selected households (5 participants with Solomon hay-box and 5 participants with Mekete Bamboo brooder) were involved and each received 50-dayoldkoikok breed chicks. The brooders were used during the night whereas chick-runs were used to hold and feed the chicks during the day. During the brooding period (up to 8 weeks old), chicks were fed on commercial starter ration. Water was provided to chickens at ad libitum. All collected data were analyzed by using statistical package for social science (SPSS) version 20.0. The total cost for building Solomon hay-box with 50 chicken capacities was 4600BIRR and 910BIRR for Mekete bamboo brooder. About 92, 89.2, 87.6 and 86% of chick survivability was recorded at 2nd, 4th, 6th and 8th weeks, respectively at Solomon hay-box and for Mekete bamboo brooder the result was 94.8, 91.6, 90 and 88.8% at 2nd, 4th, 6th and 8th weeks, respectively. The average age at first egg laying at Solomon hay-boxwas 139.6 days and 145.4 days at Mekete bamboo brooder. Average weight of eggs at Solomon hay-boxwas 39.16 g and 38.38 g at Mekete bamboo brooder. The average weight of male and female chicken at 20 weeks of age was 1.63 and 1.18 kg, respectively at Solomon hay-box and 1.61 and 1.18 kg for Mekete bamboo brooder. Both brooders have almost similar capacity in all compared parameters except that of cost of input. So, introducing economical brooder is compulsory to increases profitability of farmers.

Foster rather than biological parental telomere length predicts offspring survival and telomere length in king penguins.

Because telomere length and dynamics relate to individual growth, reproductive investment and survival, telomeres have emerged as possible markers of individual quality. Here, we tested the hypothesis that, in species with parental care, parental telomere length can be a marker of parental quality that predicts offspring phenotype and survival. In king penguins (Aptenodytes patagonicus), we experimentally swapped the single egg of 66 breeding pairs just after egg laying to disentangle the contribution of prelaying parental quality (e.g., genetics, investment in the egg) and/or postlaying parental quality (e.g., incubation, postnatal feeding rate) on offspring growth, telomere length and survival. Parental quality was estimated through the joint effects of biological and foster parent telomere length on offspring traits, both soon after hatching (day 10) and at the end of the prewinter growth period (day 105). We expected that offspring traits would be mostly related to the telomere lengths (i.e., quality) of biological parents at day 10 and to the telomere lengths of foster parents at day 105. Results show that chick survival up to 10days was negatively related to biological fathers' telomere length, whereas survival up to 105days was positively related to foster fathers' telomere lengths. Chick growth was not related to either biological or foster parents' telomere length. Chick telomere length was positively related to foster mothers' telomere length at both 10 and 105days. Overall, our study shows that, in a species with biparental care, parents' telomere length is foremost a proxy of postlaying parental care quality, supporting the "telomere - parental quality hypothesis."

Fluctuations in field vole abundance indirectly influence red grouse productivity via a shared predator guild

Changes in the abundance of one prey species may indirectly affect other prey species by triggering responses in generalist predators. Here we examine relationships between two prey species that do not compete directly, the field vole Microtus agrestis, a common rodent with fluctuating populations, and the red grouse Lagopus lagopus scotica, a gamebird inhabiting open moorland, during a 27-year study on a moor in south-west Scotland. First, we test whether vole abundance was related to grouse density and demographic rates. Second, we test whether vole abundance was related to abundance indices of four common predators of both voles and grouse (red fox Vulpes vulpes, weasel Mustela nivalis, hen harrier Circus cyaneus and common buzzard Buteo buteo). Third, we test whether these vole–grouse and vole–predator relationships differ in relation to grouse management, which includes the culling of foxes and weasels. We found no association between vole abundance and grouse densities, adult summer survival or nesting success. However, the ratio of young grouse per adult and the proportion of female grouse with broods in July were negatively associated with field vole abundance, suggesting increased predation of grouse chicks in years with high vole abundance. Fox indices showed a weak positive association with vole abundance when their numbers were not controlled, whilst weasel indices showed no relationship with voles. The numbers of breeding hen harriers and buzzards were also not associated with vole abundance, but the number of buzzard sightings was higher when voles were more plentiful. Our results are consistent with a negative interaction between field voles and red grouse chick survival in a pattern expected for apparent competition. Although the underlying mechanisms could not be disentangled, this interaction may be at least partly mediated by rodent-hunting raptors such as buzzards and, in periods without grouse management, foxes.

Black Tern (Chlidonias niger) Nest Success and Incubation Behavior in Northern Michigan, United States

Nest success and chick survival are difficult to determine in Black Terns (Chlidonias niger) due to cryptic nests and chicks, challenging to access nest locations, and potential detrimental effects on nest success from increased disturbance in the colony. Nest success and attendance rates were documented in a Black Tern colony in northern Michigan, USA, in 2017 and 2018 using nest cameras and weekly site visits to overcome these challenges. Nest success was estimated at 74% (95% CI = 41%-91%) in 2017 and 81% (95% CI = 61%-92%) in 2018. Mean nest attendance during the late incubation stage (86%) was significantly higher than during the early stage (77%); and time of day had a significant effect on nest attendance rates, with adult Black Terns spending more time on the nest at night. When chicks reached 6 days post-hatch, mean diurnal nest attendance dropped to 35% or lower. Nocturnal nest attendance remained high until the chicks were 6 or more days old, then nest attendance declined precipitously. These findings may provide further insight into the use of nest cameras and potential factors limiting Black Tern nest success and chick survival in the Great Lakes.