Search

An unprecedented irruption of thousands of Razorbills Alca torda into Florida in winter 2012/13 was followed by a "wreck" of Razorbills and Atlantic Puffins Fratercula arctica in outer Cape Cod, Massachusetts, in January-March 2013. We describe these events using citizen-science sources (eBird and beached-bird surveys) and band recoveries, then we discuss them in relation to extreme weather and oceanographic change. We explored effects on likely source populations using census and monitoring data, along with possible contributions from population increases, reduced food supply, and extreme weather. Winter 2012/13 followed a marine heatwave throughout the northwest Atlantic, whose effects included reduced availability of plankton. We attribute the irruption of Razorbills into Florida partly to delayed effects of Hurricane Sandy, which disrupted their coastal habitat sufficiently to cause starving birds to move south on the Labrador Current as far as Florida. Despite the continuation of anomalously warm ocean temperatures in subsequent years and a reduction in plankton communities in the Bay of Fundy and Gulf of Maine that continues to date, no comparable events have been recorded in subsequent winters; this supports our theory that the delayed effects of Hurricane Sandy contributed to these wrecks. We highlight the power of these datasets to detect and to investigate birds' responses to extreme and anomalous conditions, which in turn provides insight into the dynamics of rapidly changing ecological systems. [ABSTRACT FROM AUTHOR]

Ecosystem-based fishery management requires understanding of relationships between exploited fish and their predators, such as seabirds. We used exploratory regression analyses to model relationships between Atlantic herring (Clupea harengus) in the diet of seabird chicks at nine nesting colonies in the Gulf of Maine and four types of fishery- and survey-derived herring data. We found several strong relationships, which suggests spatial structuring in herring stocks and likely patterns of herring movements before they recruit into the fishery. Some types of herring data seldom used in stock assessments — notably acoustic surveys, fixed-gear landings, and mass-at-age (i.e., weight-at-age) — correlated as strongly with seabird data as more commonly used series, such as mobile-gear landings and modeled spawning stock biomass. Seabird chick diets collected at specific locations thus offer a promising means to assess the size, distribution, and abundance of juvenile herring across a broad area prior to recruitment, which is a major source of uncertainty in fisheries. Common terns (Sterna hirundo) showed the most potential as a bioindicator, correlating well and showing consistent spatial patterns with 11 of 13 fishery data series. [ABSTRACT FROM AUTHOR]

ABSTRACT Lethal control of wildlife represents an ethical concern for managers, exacerbated by a lack of replicated or controlled data for most taxa or regions. The Gulf of Maine (GOM) has a history of intensive lethal and nonlethal predator control to protect terns ( Sterna spp.) from inflated populations of predatory gulls, especially herring ( Larus argentatus) and great black-backed gulls ( L. marinus; large gulls). We described management strategies in the GOM, reviewed methods of nonlethal and lethal types of control, and compared the effectiveness of 3 control regimes (lethal, nonlethal-only, and no control) using weighted means of reproductive success metrics for 4 tern species. Nonlethal-only control is the least effective method of predator control; lethal control is consistently the most effective. Arctic terns ( Sterna paradisaea) were the most susceptible to predation, whereas common terns ( Sterna hirundo) were the most resilient. We concluded that targeted lethal control is necessary in the GOM to protect tern colonies from depredation and nesting exclusion by large gulls, and cannot be substituted with nonlethal control. Cessation of lethal control leads to abandonment of tern colonies within 6-7 years, but resumption of appropriately timed lethal control can lead to recolonization the same year. A combination of nonlethal and lethal methods can minimize the number of gulls taken. We recommend that any application of lethal control carefully considers the local needs of any target species and recognizes the need for spatial and temporal commitment. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines the impact of disturbance by researchers on the breeding success of Atlantic puffins on Machias Seal Island, Maine. The impact on hatching and reproductive success of taking blood samples from adults during incubation and the difference of chick growth rates between experimental burrows and control subjects are observed. Findings show the lack of significant differences in hatching, breeding, and chick growth between the examined subjects.

The article discusses a genetic study completed in 2010 on Nihoa Millerbirds, Acrocephalus familiaris kingi in Latin, to determine how island species are affected by a myriad of factors. It states that species who are native to isolated islands are at greater risk to the arrival of non-native species, unpredictable environmental factors, and human interference. For this study, it reports that researchers conducted their studies on Nihoa, Hawaii, collecting genetic samples in 2007 and 2009. It explains the results and the genetic model used for the study.

How species allocate nutrients to egg production is an important question in contaminant analyses. Seabird eggs are sampled frequently in such studies, so it is important to know the source of nutrients in these eggs if the source of the contaminants is to be traced. We used a stable-isotope approach to evaluate the relative importance of locally derived nutrients (income breeding) and stored nutrient reserves (capital breeding) in six species of Atlantic seabirds (Arctic Tern, Sterna paradisaea Pontoppidan, 1763; Common Tern, Sterna hirundo L., 1758; Atlantic Puffin, Fratercula arctica (L., 1758); Common Murre, Uria aalge (Pontoppidan, 1763); Razorbill, Alca torda L., 1758; Leach's Storm-Petrel, Oceanodroma leucorhoa (Vieillot, 1818)) breeding in the Bay of Fundy. We found that all species either were income breeders or adopted an intermediate strategy whereby varying proportions of locally derived nutrients were incorporated into eggs. Each species' migratory behaviour is likely a main factor in determining the amount of endogenous nutrients used in egg formation. [ABSTRACT FROM AUTHOR]

Mercury is a pervasive environmental contaminant, the anthropogenic portion of which is increasing globally, and in northeastern North America in particular. Seabirds frequently are used as indicators of the marine environment, including mercury contamination. We analysed paired samples for total mercury (Hg) concentrations in feathers and blood from adult and chick, albumen, and lipid-free yolk of seven seabirds breeding on Machias Seal Island, New Brunswick, Canada ¿ Arctic Tern (Sterna paradisaea), Atlantic Puffin (Fratercula arctica), Common Eider (Somateria mollissima), Common Murre (Uria aalge), Common Tern (Sterna hirundo), Leach's Storm-petrel (Oceanodroma leucorhoa), and Razorbill (Alca torda). We also used stable-isotope ratios of carbon (¿ 13C), and nitrogen (¿ 15N) to evaluate the relationship between carbon source and trophic position and mercury. We found high Hg concentrations across tissue types in Leach's Storm-petrels, and Razorbills, with lower concentrations in other species, the lowest being in Common Eiders. Storm-petrels prey on mesopelagic fish that accumulate mercury, and Razorbills feed on larger, older fish that bioaccumulate heavy metals. Biomagnification of Hg, or the increase in Hg concentration with trophic position as measured by ¿ 15N, was significant and greater in albumen than other tissues, whereas in other tissues, ¿ 15N explained little of the overall variation in Hg concentration. Hg concentrations in egg components are higher on Machias Seal Island than other sites globally and in the Gulf of Maine region, but only for some species. Further detailed investigations are required to determine the cause of this trend. [Copyright &y& Elsevier]

This article focuses on a study which estimated the probability of survival, re-encounter and dispersal of Arctic Terns nesting in the Gulf of Maine and the Bay of Fundy using capture-mark-recapture analysis of a metapopulation. Researchers used modified treadle traps or bow traps to catch Arctic Terns beginning in the second week of incubation. Researchers recorded 54 Arctic Terns breeding on islands outside the colony where they were originally banded as breeding adults.

During their annual mid- to late-summer southward migration, Semipalmated Sandpipers ( Calidris pusilla) feed intensively on the amphipod Corophium volutator on intertidal mudflats in the Bay of Fundy. Corophium, in turn, feed on diatoms and bacteria. Using a series of bird exclosures and fertilizer addition, we examined top–down and bottom–up effects, and investigated the presence of a trophic cascade in the mudflat community during the period when birds are abundant. Although both top–down and bottom–up forces were present in this system, neither transmitted beyond a single trophic link. Predation by shorebirds, which may be less size-selective than previously thought, reduced Corophium abundance in control plots by approximately 80% relative to exclosures, but most other species were unaffected. Shorebird predation did not result in an increase in diatom abundance, as predicted under the trophic cascade hypothesis. Fertilizer increased diatom abundance, but had no effect on Corophium abundance or bird predation, and little effect on other mudflat invertebrates. The only indirect effect observed was on mud snails ( Ilyanassa obsoleta), which, by rapidly responding to changes in diatom abundance, compensated for both bird exclusion and fertilizer addition, and prevented the trophic cascade. This population response by snails, possibly stemming from competition with Corophium, probably contributed to the stability of the community. Our results provide an example of short-term compensation in a simple intertidal community, and highlight the importance of considering direct and indirect effects in community ecological studies. We conclude that while compensatory interactions that block trophic cascades may be more common in more complex ecosystems, they are not restricted to them. [ABSTRACT FROM AUTHOR]

Several weaknesses in our understanding of long-lived animal populations have persisted, mainly due to a prevalence of studies of a single local population at the expense of multisite studies. We performed a multisite capture-mark-resight analysis using 2050 Atlantic Puffins (Fratercula arctica) banded as chicks on four islands (colonies) over 24 years in the Gulf of Maine, USA and Canada. Within program MARK; encounter, apparent survival, pre- breeding movement (PBM; annual movements between colonies prior to breeding), and natal dispersal (ND) probabilities were modeled as functions of age, colony, and several covariates. Information-theoretic model selection criteria and estimated model effect sizes were used to identify important effects and select models, to estimate parameters. Encounter probabilities were extremely variable (0.10–0.95) and declined annually starting six years after bands were applied, due to changes in resighting effort, and band wear, respectively. Colony-dependent survival probabilities increased to a peak at age six years; arithmetic means from all colonies were: 0.70 for age 0–3, 0.78 for age 4, 0.81 for age 5, and 0.84 for age 6–8 years. Low adult survival (age ≥15 years) may reflect inclusion of breeding and nonbreeding adults in our sample or a bias due to band loss and illegibility. Consistent with a density-dependent prediction, the effect of colony size on survival was negative and acquired strong AICc support. However, this effect was inconsistent with strata effects in competing top models; the latter suggest that survival was lowest on the smallest island. The effects of origin and destination colony and origin colony size in PBM and ND probabilities resulted in important variation in these parameters. As few as 8% and as many as 57% of the puffins that we marked may have bred away from their natal colony, a signal of highly variable philopatry. Consistent with the con-specific attraction hypothesis, ND and PBM probabilities declined as the size of the origin colony increased. PBM probabilities were highest in the age 0–3 period, and these declined quickly with age thereafter. Strong colony and age effects in ND and PMB probabilities identify movement as a critical contributor to local population dynamics at our four study sites. [ABSTRACT FROM AUTHOR]

We report survival probabilities for 148 breeding adult Atlantic Puffins (Fratercula arctica) monitored through capture-mark-resight at two colonies for 11 years (1992-2003). The colonies. Eastern Egg Rock and Seal Island, are ∼42 km apart in the Gulf of Maine. Support for competing models in the program MARK suggests constant survival of 0.95 ± 0.01 (SE) that is independent of colony. Our high survival probability is consistent with published estimates for Atlantic Puffins and other long-lived seabirds. No time-variance contrasts with many long-term seabird studies, which often report high survival in most years, broken occasionally by low-survival events. However, a post-hoc observation of survival estimates from the time-dependent model suggests that there may have been at least two low-survival events in our time-series; sparse data may have precluded detection by our models. In this study, each bird received an individually engraved, plastic, field-readable leg band, as well as the standard metal band. Using an index of band readability, we show that plastic bands wore rapidly, resulting in accumulating losses of engraved characters through time. Degradation and loss of marks is a common source of overdispersion in capture-mark-re-encounter data and results in underestimated sampling variances. In the presence of a 70% reduction in band readability over eight years, an estimate of the adjusted overdispersion factor (ĉ = 1.14) identified very little overdispersion in our data. Overdispersion was avoided by double banding and intensively resighting metal bands. [ABSTRACT FROM AUTHOR]

Studies changes in population among boreal forest birds in Saskatchewan and Manitoba. Decrease of neotropical migrants in Saskatchewan; Reason for the increase in some species; Differences in the neotropical migrant species; Reduction for breeding opportunities; Effect of agricultural practices.

To our knowledge, no rigorous assessment of the variation in mercury concentrations within individual seabirds has been made using multiple body feathers. We analyzed five feathers from individual Arctic terns (Sterna paradisaea Pontoppidan), common terns (Sterna hirundo L.), and Leach's storm-petrels (Oceanodroma leucorhoa Veillot) and found levels of within-individual variability higher than population or time-series variation. Using a randomization procedure, we found a large range of possible mercury concentrations if only one feather per individual had been sampled. Researchers should report within-individual variability in future studies. [ABSTRACT FROM AUTHOR]

Climate change imposes physiological constraints on organisms particularly through changing thermoregulatory requirements. Bergmann's and Allen's rules suggest that body size and the size of thermoregulatory structures differ between warm and cold locations, where body size decreases with temperature and thermoregulatory structures increase. However, phenotypic plastic responses to malnutrition during development can result in the same patterns while lacking fitness benefits. The Gulf of Maine (GOM), located at the southern end of the Labrador current, is warming faster than most of the world's oceans, and many of the marine species that occupy these waters exist at the southern edge of their distributions including Atlantic puffins (Fratercula arctica; hereafter "puffin"). Monitoring of puffins in the GOM, at Machias Seal Island (MSI), has continued annually since 1995. We asked whether changes in adult puffin body size and the proportional size of bill to body have changed with observed rapid ocean warming. We found that the size of fledgling puffins is negatively related to sea surface temperature anomalies (warm conditions = small fledgers), adult puffin size is related to fledgling size (small fledgers = small adults), and adult puffins have decreased in size in recent years in response to malnutrition during development. We found an increase in the proportional size of bill to wing chord, likely in response to some mix of malnutrition during development and increasing air temperatures. Although studies have assessed clinal variation in seabird morphology with temperature, this is the first study addressing changes in seabird morphology in relation to ocean warming. Our results suggest that puffins nesting in the GOM have morphological plasticity that may help them acclimate to ocean warming. [ABSTRACT FROM AUTHOR]

Arctic Terns (Sterna paradisaea) are iconic seabirds of polar latitudes, whose successful reproduction is thought to depend on local food supplies near breeding colonies. We used stable isotopes of carbon and nitrogen in eggs, blood, and feathers of terns breeding in the Canadian High Arctic to compare their isotopic niche between life history stages and between two years. The isotopic niche of terns was smaller during incubation than during pre-breeding or winter. Over two breeding seasons, isotopic profiles of Arctic Terns suggested the high importance of local, exogenous nutrient supplies to form eggs (i.e., an income breeding strategy). Our results illustrate that using stable isotopes to assess the niche of a seabird population during critical periods of its annual cycle could be an essential tool in determining the influence that local forage conditions have on breeding decisions, especially for species that mostly rely on exogenous sources of nutrients and energy for egg production. [ABSTRACT FROM AUTHOR]

The predator-prey interactions within food chains are used to both characterize and understand ecosystems. Conventional methods of constructing food chains from visual identification of prey in predator diet can suffer from poor taxonomic resolution, misidentification, and bias against small or completely digestible prey. Next-generation sequencing (NGS) technology has become a powerful tool for diet reconstruction through barcoding of DNA in stomach content or fecal samples. Here we use multi-locus (16S and CO1) next-generation sequencing of DNA barcodes on the feces of Atlantic puffin (Fratercula arctica) chicks (n=65) and adults (n=64) and the stomach contents of their main prey, Atlantic herring (Clupea harengus, n=44) to investigate a previously studied food chain. We compared conventional and molecular-derived chick diet, tested the similarity between the diets of puffin adults and chicks, and determined whether herring prey can be detected in puffin diet samples. There was high variability in the coverage of prey groups between 16S and CO1 markers. We identified more unique prey with our 16S compared to CO1 barcoding markers (51 and 39 taxa respectively) with only 12 taxa identified by both genes. We found no significant difference between the 16S-identified diets of puffin adults (n=17) and chicks (n=41). Our molecular method is more taxonomically resolved and detected chick prey at higher frequencies than conventional field observations. Many likely planktonic prey of herring were detected in feces from puffin adults and chicks, highlighting the impact secondary consumption may have on the interpretation of molecular dietary analysis. This study represents the first simultaneous molecular investigation into the diet of multiple components of a food chain and highlights the utility of a multi-locus approach to diet reconstruction that is broadly applicable to food web analysis. [ABSTRACT FROM AUTHOR]

Catharus bicknelli (Bicknell's Thrush) is a rare and globally vulnerable songbird often found in regenerating clearcuts in the Canadian maritime provinces and Québec. Previous studies have shown correlations between vegetation characteristics and occurrence and abundance of this species, but no study has described vegetation associated with Bicknell's Thrush nests in managed forests. From 2007-2010, we investigated nest-habitat selection of Bicknell's Thrush in the industrial forestry landscape of north-central New Brunswick. We compared vegetation composition and structure in 5-m-radius patches around nests to vegetation in a random control-patch within the home range of each Bicknell's Thrush. Precommercial thinning (PCT) is a forest-management treatment that may reduce the suitability of habitat for Bicknell's Thrush, thus we also examined the percent of the landscape treated by this practice around Bicknell's Thrush nests. We found that Bicknell's Thrush preferentially selected nest sites with a significantly lower proportion of deciduous trees and higher overall tree density than randomly sampled habitat within their home range. We also found that an average of 44% of the area within 500 m of Bicknell's Thrush nests was treated by PCT, and most had been treated within 3-5 years of our study. We suggest that small patches of dense, Abies balsamea (Balsam Fir)-dominated forest within a thinned matrix may be sufficient to provide nesting sites for Bicknell's Thrush; however, it remains unclear if these areas support production of young or if they are population sinks. PCT could have serious negative consequences on Bicknell's Thrush breeding success and on the longterm survival of the species in Canada; thus, we encourage silviculture treatments that leave unthinned areas for nesting of Bicknell's Thrush in managed forests. [ABSTRACT FROM AUTHOR]

Theory predicts the occurrence of threshold levels of habitat in landscapes, below which ecological processes change abruptly. Simulation models indicate that below critical thresholds, fragmentation of habitat influences patch occupancy by decreasing colonization rates and increasing rates of local extinction. Uncovering such putative relationships is important for understanding the demography of species and in developing sound conservation strategies. Using segmented logistic regression, we tested for thresholds in occurrence of 15 bird species as a function of the amount of suitable habitat at multiple scales (150–2000-m radii). Suitable habitat was defined quantitatively based on previously derived, spatially explicit distribution models for each species. The occurrence of 10 out of 15 species was influenced by the amount of habitat at a landscape scale (≥500-m radius). Of these species all but one were best predicted by threshold models. Six out of nine species exhibited asymptotic thresholds; the effects of habitat loss intensified at low amounts of habitat in a landscape. Landscape thresholds ranged from 8.6% habitat to 28.7% ( = 18.5 ± 2.6%[95% CI]). For two species landscape thresholds coincided with sensitivity to fragmentation; both species were more likely to occur in large patches, but only when the amount of habitat in a landscape was low. This supports the fragmentation threshold hypothesis. Nevertheless, the occurrence of most species appeared to be unaffected by fragmentation, regardless of the amount of habitat present at landscape extents. The thresholds we identified may be useful to managers in establishing conservation targets. Our results indicate that findings of landscape-scale studies conducted in regions with relatively high proportions of habitat and low fragmentation may not be applicable in regions with low habitat proportions and high fragmentation. [ABSTRACT FROM AUTHOR]

In the eastern North Atlantic, declines in the volume of Atlantic Puffin (Fratercula arctica (Linnaeus, 1758)) eggs have been associated with shifts in the marine ecosystem, such as changes in the abundance of forage fishes and increasing sea-surface temperatures. In the western North Atlantic, where similar shifts in oceanographic conditions and changes in the abundance of forage fishes have presumably occurred, trends in the volume of Atlantic Puffin eggs remain unknown. In this study, we investigate Atlantic Puffin egg volume in the western North Atlantic. We compiled 140 years (1877–2016) of egg volume measurements (n = 1805) and used general additive mixed-effects models to investigate temporal trends and regional variation. Our findings indicate that Atlantic Puffin egg volume differs regionally but has remained unchanged temporally in the western North Atlantic since at least the 1980s. [ABSTRACT FROM AUTHOR]

The upper Bay of Fundy is a critical staging area for migrating semipalmated sandpipers (Calidris pusilla), which feed extensively on the amphipod Corophium volutator. Recent changes in the distributions of birds around the bay have generated interest in understanding the factors that influence shorebirds' habitat use. To examine some of these factors, we surveyed four mud flats during summer 2000. Abundance of shorebirds and density of C. volutator and mud snails (Ilyanassa obsoleta) were assessed in two focused areas and on two broad-scale transects per mud flat. Shorebird abundance varied widely across sites, and was positively correlated with C. volutator availability, though the relationship had little predictive ability. A strong negative relationship was identified between shorebirds and mud snails counted before birds arrived, especially in the focused areas. This relationship probably stems from a negative effect of mud snails on C. volutator. Snails present in July may reduce recruitment of C. volutator, and therefore reduce the prey base for shorebirds arriving later in the summer. By considering mud snail abundance, we have identified a simple and effective method of predicting shorebird habitat use several weeks before birds arrive. This will enhance our ability to study these birds in future, and will contribute to our understanding of shorebird habitat use and movements and the importance of conserving particular mud flats. [ABSTRACT FROM AUTHOR]

Studies the use of regenerating clear cuts in the central highlands of New Brunswick by Bicknell's and Swainson's thrushes during the 1997 breeding season. Density estimates of Bicknell's and Swainson's thrushes; Results of multivariate regression modelling of habitat variables; Species that has a lower probability of detection.

Age is an important parameter for a variety of ecological applications, including population viability analyses, contaminants monitoring and targeting of individuals for conservation. While many organisms can be aged by annual rings, dentition and other techniques (i.e., fish otoliths, clam growth rings, mammal tooth wear), there are no minimally invasive biomarkers for accurately aging birds in the wild. For the past century, banding has been the only way to identify a bird of known age, which requires continuous effort on a large scale with possibly low return rates. Recent studies have identified pentosidine as a potential biomarker of chronological aging in several bird species. To test this idea in four species of long-lived seabirds, we collected skin biopsies from the foot webs of previously banded, known-age seabirds: black-legged kittiwakes (Rissa tridactyla ; 0–19 y old), Atlantic puffins (Fratercula arctica ; 5–26 y old), razorbills (Alca torda ; 0–15 d old) and thick-billed murres (Uria lomvia ; 0–35 y old). Foot web samples were specifically chosen because this was the least invasive site for substantial skin biopsy. Samples were analysed with high performance liquid chromatography to quantify pentosidine levels. Collagen levels were estimated through hydroxyproline assays to normalize pentosidine content across individuals. Kittiwakes displayed a weak correlation (r2 = 0.20) between age and pentosidine/collagen. Puffins (adults only, r2 = 0.02), razorbills (chicks only, r2 = 0.08), and murres (adults, r2 = 0.04) did not show any associations with age. We concluded that pentosidine content in the foot web does not appear to be a reliable method for aging seabirds in the wild. An absence of change in pentosidine in the foot web with age is further evidence that long-lived seabirds may maintain physiological performance into old age. • Pentosidine is a biomarker for biological age in mammals and short-lived birds. • We investigated the potential of foot-web pentosidine as a biomarker for age in long-lived birds. • There was a (weak) association between foot-web pentosidine and age in only one of four species. [ABSTRACT FROM AUTHOR]

Systematic monitoring of seabird populations in Canada has been ongoing since the 1920s and the monitoring of diets and other biological indicators of ecosystem change started in the 1970s. Long-term monitoring of population parameters began in the 1980s. These studies originally were conducted mainly by the Canadian Wildlife Service, but subsequently have involved several universities and nongovernment organization groups. We review the results of this monitoring from the 1970s onwards for six oceanographic regions to assess population trends among Canadian seabirds and correlated trends in diets, phenology, and other breeding biology variables. Within regions, trends in most variables studied have been broadly congruent, but there was often variation among regions. In particular, seabird populations in the Pacific coast zone affected by the California Current upwelling system have shown generally negative trends since the 1980s, whereas trends for populations of the same species to the north of this zone have been mainly positive. Likewise, on the east coast, trends at Arctic colonies have been decoupled from those at colonies around Newfoundland and in the Gulf of St. Lawrence, especially since the major cold water event of the early 1990s. Several long-term studies have shown an association between population events and diet and phenology changes. Diet and indicators of condition (chick growth, reproductive success) sometimes responded very rapidly to oceanic changes, making them excellent signals of ecosystem perturbations. The review highlights the effects of decadal-scale regime shifts on Canadian seabirds, confirms the value of long-term studies and supports the applicability of single-site observations to regional populations. [ABSTRACT FROM AUTHOR]

Life history theory predicts that parents will have lower Darwinian fitness if they tend clutches that are above or below the size they naturally produce. We experimentally tested for relationships between fitness and clutch size in Tree Swallow (Tachycineta bicolor) offspring and parents. Over 130 trios of nests initiated on the same day were randomly divided among reduce (-3 eggs), control (3 eggs picked up and replaced), or add (+3 eggs) manipulations. Pre-manipulation modal clutch size was six eggs (range before manipulations was 1–10; afterwards, it was 1–11). Hatching took longer in larger clutches, but the proportion of eggs hatching and fledging was similar for clutches from 4 to 10, so that clutches of l0 produced the maximum number of fledgling. Parental feeding rates were higher for larger broods, but per capita feeds to nestlings were fewer, and nestlings were smaller. Nonetheless, survival of both young and adults, based on recaptures in subsequent years, was not significantly affected by manipulations. Manipulations also had no significant effect on subsequent reproduction, including the number of fledglings produced by either local recruits or returning breeders. Collectively, our results failed to detect fitness costs associated with tending larger clutches for either parents or the offspring reared and suggested directional selection for larger clutch size. However, because clutches that hatch later produce fewer recruits, the extra days required to lay more eggs and to fledge extra young may eliminate a large part of the advantage that would accrue to parents producing enlarged clutches. For example, our data suggest that there may be less than a 16% benefit to producing nine instead of Six eggs, rather than 50%, as is suggested by experimentally manipulated egg numbers alone. Thus, time, rather than costs of reproduction, may be the crucial constraint selecting against Tree Swallows laying larger clutches. [ABSTRACT FROM AUTHOR]

Endogenous reserves influence both survival and reproduction of many waterfowl species, but little is known about reserve levels of most species during the nonbreeding season, particularly those wintering at high latitudes. We investigated whether age, sex, and season were related to carcass composition of northern common eiders ( Somateria mollissima borealis) wintering in southwest Greenland during 1999–2002. Adults carried more lipid and protein than juveniles during all winters. Among both age classes, males and females had similar fat levels but males carried slightly more protein. There was no dramatic seasonal variation in lipid or protein content. This suggests that during the period of this study, these eiders did not experience large-scale nutritional shortfalls. As predicted, Greenlandic eiders carried more lipid reserves than eider populations wintering in more temperate environments. Contrary to prediction, there was little relation between reserve levels and photoperiod, ambient temperature, or hunting disturbance intensity. Our results suggest that both sexes are equally capable of dealing with nutritional deficits, and that juvenile birds are more prone to nutritional stress as evidenced by their consistently poorer body condition. [ABSTRACT FROM AUTHOR]

From observations made on Manawagonish Island, NB in 2002 and 2004, we provide first documentation of the Ring-billed Gull (Larus delawarensis Ord) nesting in the Bay of Fundy. These observations counter suggestions that this species is no longer expanding its breeding range in the Maritimes. We also place this event in a broader context in which other coastal marine bird species have been recorded expanding or reclaiming breeding ranges in the region in recent decades. [ABSTRACT FROM AUTHOR]

A correction to the article "Changes in Canadian Seabird Populations and Ecology Since 1970 in Relation to Changes in Oceanography and Food Webs" is presented.