Breeding Population Size Research Articles

Breeding Population of Red-Legged Cormorant (Phalacrocorax gaimardi) along the Araucania Region Coast, South-Central Chile

The Red-legged Cormorant (Phalacrocorax gaimardi) is a neotropical cormorant with a moderately small population and is currently categorized as “Near Threatened” by the International Union for Conservation of Nature. The Red-legged Cormorant is distributed only along the coasts of Peru, Argentina and Chile; however, the most important breeding population for this species occurs within a small area in Chile. Between 1998 and 2000, the entire breeding population size of the Red-legged Cormorant and its distribution in Chile were determined, but some areas were poorly surveyed. The breeding population sizes of the Red-legged Cormorant were surveyed along the Araucania coast, an area in south-central Chile not considered in previous studies. A total of 3,175 nests and 13,018 adults were distributed over 10 breeding colonies along the Araucania coast. Our results increased the known breeding population size of the Red-legged Cormorant in Chile by almost 62% (from 5,018–5,218 to 8,193–8,393 breeding pairs) and the rangewide population estimate by almost 43% (from 30,000 to 43,018 individuals). This area could be one of the most important breeding areas for this species throughout its range. Currently, the colonies of Piureo-Puaucho (1,506 nests), Nigue (1,009 nests) and Punta Ronca (Queule) (964 nests) represent almost 42% of the breeding population of this species in Chile, so these breeding sites should be a priority for conservation efforts.

Assessing predictions of population viability analysis: Peregrine Falcon populations in California.

Population viability analysis (PVA) has been an important tool for evaluating species extinction risk and alternative management strategies, but there is little information on how well PVA predicts population trajectories following changes in management actions. We tested previously published predictions from a stage-structured PVA of Peregrine Falcons (Falco peregrinus) in California, USA (Wootton and Bell 1992), against population trajectories following the 1992 termination of statewide, active management (population supplementation of captive-reared young). In the absence of extensive post-management monitoring, we developed surrogate estimates of breeding population size by calibrating several citizen science data sets (Christmas Bird Count, CBC; and North American Breeding Bird Survey, BBS) to intensive population surveys taken primarily during the active management period. CBC abundance data standardized by observer effort exhibited a strong relationship to intensive survey data (r2 = 0.971), indicated significantly reduced annual population growth rates after management was terminated (λ = 0.023 ± 0.013 SE) than when supplementation occurred (λ = 0.089 ± 0.023 SE), and demonstrated an increasing population as predicted by the PVA. The population trajectory fell within the 95% CI of stochastic simulations of the model either with or without density dependence and assuming either measurement error or process error, but models with process error were most strongly supported by the data. These results indicate that PVA can quantitatively anticipate population trajectories following changes in management, highlight the importance of post-management monitoring of species of concern, and illustrate the benefits of using management changes as large-scale experiments to more rigorously test PVA.

Are nest-detection probability methods relevant for estimating turtle dove breeding populations? a case study in Moroccan agroecosystems

Knowing the population size of game is a basic prerequisite to determining adequate hunting management and conservation strategies and setting up appropriate hunting quotas. This study compared three methods complete count, capture–recapture and N-mixture modelling to estimate a turtle dove Streptopelia turtur breeding population using nest counts. We randomly sampled 143 fruit farms (60 orange orchards and 83 olive orchards) situated in an irrigated area in Morocco at the peak of breeding activity. We calculated the probability of detecting active turtle dove nests using information from two observers who independently searched the same sample plots. We found that (a) the capture–recapture method provided more precise results of nest abundance than N-mixture modelling, and that (b) the probability of nest detection was noticeably different between the two study orchards—higher in the orange orchards than in the olive orchards. Although these two methods are easy to implement and cost-effective for estimating population abundance on a large spatial scale, our results demonstrate that the resulting estimates are prone to bias depending on the tree height of the plantations. Of the three methods for estimating turtle dove abundance, complete counts were preferable for assessing population size. Using the complete counts, the density of turtle dove nests was found to be 2.96 nests/ha in the orange orchards and 0.93 nests/ha in the olive orchards. A density extrapolation to the entire surface area of the Tadla Region indicated a minimum breeding population size of 58,969 pairs (95 % confidence interval: 48,550–69,353).

The potential use of artificial nests for the management and sustainable utilization of saker falcons (Falco cherrug)

Artificial nests are a commonly used manage- ment technique to increase the breeding population and/or productivity of birds with nest site limited populations. We compared nest survival of saker falcons breeding in artifi- cial nests erected in a flat steppe landscape with those breeding in natural nests on rocks and cliffs in adjacent hills of central Mongolia. We found no significant differ- ence in daily nest survival during the egg and nestling stages of the breeding cycle. Nest survival varied across years and was higher at artificial than natural nest sites, primarily because of higher survival rates during the egg stage at artificial nests. However, fledgling productivity was not significantly different although artificial nests produced an average of 3.2 fledglings compared to 2.3 at natural nest sites. We found no significant differences in offspring sex ratios and fledgling mass at artificial and natural nest sites. Provision of artificial nests can increase the range, size and productivity of saker falcon breeding populations, a globally endangered species subject to high mortality and trapping for falconry. This management technique can be used for incentive-driven conservation initiatives, whereby sustainable harvest quotas can be generated from demographic models based on parameters derived from a managed and monitored population breed- ing in artificial nests.

Combining site occupancy, breeding population sizes and reproductive success to calculate time-averaged reproductive output of different habitat types: an application to Tricolored Blackbirds.

In metapopulations in which habitat patches vary in quality and occupancy it can be complicated to calculate the net time-averaged contribution to reproduction of particular populations. Surprisingly, few indices have been proposed for this purpose. We combined occupancy, abundance, frequency of occurrence, and reproductive success to determine the net value of different sites through time and applied this method to a bird of conservation concern. The Tricolored Blackbird (Agelaius tricolor) has experienced large population declines, is the most colonial songbird in North America, is largely confined to California, and breeds itinerantly in multiple habitat types. It has had chronically low reproductive success in recent years. Although young produced per nest have previously been compared across habitats, no study has simultaneously considered site occupancy and reproductive success. Combining occupancy, abundance, frequency of occurrence, reproductive success and nest failure rate we found that that large colonies in grain fields fail frequently because of nest destruction due to harvest prior to fledging. Consequently, net time-averaged reproductive output is low compared to colonies in non-native Himalayan blackberry or thistles, and native stinging nettles. Cattail marshes have intermediate reproductive output, but their reproductive output might be improved by active management. Harvest of grain-field colonies necessitates either promoting delay of harvest or creating alternative, more secure nesting habitats. Stinging nettle and marsh colonies offer the main potential sources for restoration or native habitat creation. From 2005–2011 breeding site occupancy declined 3x faster than new breeding colonies were formed, indicating a rapid decline in occupancy. Total abundance showed a similar decline. Causes of variation in the value for reproduction of nesting substrates and factors behind continuing population declines merit urgent investigation. The method we employ should be useful in other metapopulation studies for calculating time-averaged reproductive output for different sites.

Breeding to non-breeding population ratio and breeding performance of the globally Endangered Lear’s MacawAnodorhynchus leari: conservation and monitoring implications

SummaryLear’s MacawAnodorhynchus leariis currently listed as “Endangered” by IUCN. Although it only breeds on cliffs at two protected sites in Bahia State, Brazil, there is no accurate information on population parameters such as the number of breeding pairs and their breeding performance. Between 2009 and 2010, we sought to quantify, for the first time, breeding population size and the main breeding parameters for the species in the two known breeding sites, by quantifying the number of active nests and monitoring 75 breeding attempts. Overall, 80% of the breeding attempts were successful with 1.33 (± 0.86 SD) fledglings/breeding attempt (productivity) and 1.67 (± 0.60 SD) fledglings/successful nest (brood size). Breeding success and productivity were higher in 2010, while brood size did not vary between years and breeding sites. By adding 73 estimated nests to the 41 nests monitored, 228 individuals were estimated to be reproductively active in 2010, representing c.20% of the population (1,125 individuals). Given that the species is confined to a single population, further population increases could provoke overcrowding and negative density-dependent effects if it does not expand geographically. Therefore, long-term population monitoring focusing on the fraction of the population that is actually breeding and its breeding performance, rather than solely on the whole population size, is important for a better understanding of the population dynamics and conservation of this species.

A method for estimating colony sizes of Adélie penguins using remote sensing imagery

Adelie penguins (Pygoscelis adeliae) are important predators of krill (Euphausia spp.) and Antarctic silverfish (Pleuragramma antarctica) during summer, are a key indicator of the status of the Southern Ocean ecosystem, and are therefore a focal species for the Committee for the Conservation of Antarctic Marine Living Resources (CCAMLR) Ecosystem Monitoring Program. The ability to monitor the population size of species potentially affected by Southern Ocean fisheries, i.e., the Adelie penguin, is critical for effective management of those resources. However, for several reasons, direct estimates of population size are not possible in many locations around Antarctica. In this study, we combine high-resolution (0.6 m) satellite imagery with spectral analysis in a supervised classification to estimate the sizes of Adelie penguin breeding colonies along Victoria Land in the Ross Sea and on the Antarctic Peninsula. Using satellite images paired with concurrent ground counts, we fit a generalized linear mixed model with Poisson errors to predict the abundance of breeding pairs as a function of the area of current-year guano staining identified in the satellite imagery. Guano-covered area proved to be an effective proxy for the number of penguins residing within. Our model provides a robust, quantitative mechanism for estimating the breeding population size of colonies captured in imagery and identifies terrain slope as a significant component influenc- ing apparent nesting density. While our high-resolution satellite imagery technique was developed for the Adelie penguin, these principles are directly transferrable to other colonially nesting seabirds and other species that aggregate in fixed localities.

Populations of a cyprinid fish are self-sustaining despite widespread feminization of males.

BackgroundTreated effluents from wastewater treatment works can comprise a large proportion of the flow of rivers in the developed world. Exposure to these effluents, or the steroidal estrogens they contain, feminizes wild male fish and can reduce their reproductive fitness. Long-term experimental exposures have resulted in skewed sex ratios, reproductive failures in breeding colonies, and population collapse. This suggests that environmental estrogens could threaten the sustainability of wild fish populations.ResultsHere we tested this hypothesis by examining population genetic structures and effective population sizes (Ne) of wild roach (Rutilus rutilus L.) living in English rivers contaminated with estrogenic effluents. Ne was estimated from DNA microsatellite genotypes using approximate Bayesian computation and sibling assignment methods. We found no significant negative correlation between Ne and the predicted estrogen exposure at 28 sample sites. Furthermore, examination of the population genetic structure of roach in the region showed that some populations have been confined to stretches of river with a high proportion of estrogenic effluent for multiple generations and have survived, apparently without reliance on immigration of fish from less polluted sites.ConclusionsThese results demonstrate that roach populations living in some effluent-contaminated river stretches, where feminization is widespread, are self-sustaining. Although we found no evidence to suggest that exposure to estrogenic effluents is a significant driving factor in determining the size of roach breeding populations, a reduction in Ne of up to 65% is still possible for the most contaminated sites because of the wide confidence intervals associated with the statistical model.

Sex Ratio and Breeding Population Size in Fowler's Toad, Anaxyrus ( = Bufo) fowleri

Sex ratios among anurans at breeding sites are routinely observed to be skewed toward males, which has implications for the strength of sexual selection in these animals. However, the relative numbers of males and females observed at breeding sites also depends upon their relative conspicuousness and the physical sex ratio of the adult population as a whole, which includes animals not present at breeding sites. Using intensive capture–recapture methods, I estimated abundances of both sexes of Fowler's Toads in a population at Long Point, Ontario, over a span of 14 years (1998 to 2011, incl.). Although males greatly outnumbered females at breeding sites, persisted there for longer periods of time, and were more readily re-captured, both sexes could be found in their lakeshore non-breeding habitat with equivalent reliability. Estimates of abundance were calculated for each sex based on 3,162 total captures of 686 females and 982 males. The abundances of males and females each year were not significantly different (P = 0.738), which was consistent with a 1∶1 physical sex ratio. Both sexes also exhibited large, but strongly correlated (P << 0.001; R2 = 0.838), variations in their abundance over the 14 yrs. Only 39% of total estimated males were found at breeding sites. The ratio of males at breeding sites to total males declined significantly (P = 0.002; R2 = 0.542) over the 14-year study, in parallel with a diminishing availability of breeding sites.

Long-Term Population Trends of Colonial Wading Birds Breeding in Doñana (Sw Spain) in Relation to Environmental and Anthropogenic Factors

Breeding season counts of nine species of colonial wading birds (Nycticorax nycticorax, Ardeola ralloides, Bubulcus ibis, Egretta garzetta, Ardea cinerea, Ardea purpurea, Ciconia ciconia, Plegadis falcinellus and Platalea leucorodia) nesting at Donana during 1984–2010 were analysed. The aim of the study was to assess the size and trends of populations and to analyse their environmental and anthropogenic determinants. We used the TRIM programme to test for long-term trends, and Generalised Additive Models to assess the effect of local rainfall, the surface area of ricefields surrounding Donana and rainfall in the Sahel on breeding population size. All species showed positive population trends, mainly from 1996 onwards. The number of active colonies increased over time, and up to 17,297 nests from the nine studied species were recorded in one year (2010). Low precipitation (< 500 mm) in the previous autumn and winter was associated with reductions in the numbers of breeders, since rainfall determines the flooding extent in the natural marshes of Donana. The area of ricefields positively influenced the breeding numbers of five species. Only four of these species are considered to be increasing in Europe and increases in Donana coincide with management changes that have improved nesting and feeding habitat and reduced human disturbance. In addition to large-scale man-made habitat changes, breeding population sizes for the studied species were strongly influenced by high annual variation in rainfall, typical of Mediterranean habitats, therefore making them likely to be affected by climate change.

Establishing accurate baseline estimates of breeding populations of a burrowing seabird, the grey-faced petrel (Pterodroma macroptera gouldi) in New Zealand

Accurate estimates of breeding population size are essential for detecting change and guiding conservation management and sustainable use. In New Zealand, the grey-faced petrel (Pterodroma macroptera gouldi) now breeds predominantly on offshore islands, but is also subject to customary harvest of chicks by northern tribes of Māori (New Zealand’s indigenous peoples). We used island-wide surveys of 3186 breeding burrows, corrected for detection error, and associated habitat variables on two island systems (Ruamaahua Islands and Moutohorā), combined with data from geographic information systems, to build hierarchical Bayesian models to predict the distribution and abundance of breeding pairs. Burrow densities increased with elevation on all islands and, on Moutohorā, were lesser in gullies and on terraces. On the Ruamaahua Islands, burrow densities were associated positively with deeper soils and forests dominated by pōhutukawa (Metrosideros excelsa), and negatively with taller forest, denser canopy cover, and northern and western aspects. Predicted breeding-pair densities for each island group provided breeding-pair population estimates of 72,410 (95% credible interval 14,280–138,400) across the Ruamaahua Islands and 69,330 (10,590–128,300) on Moutohorā. Estimating burrow densities using habitat characteristics provided greater precision and accuracy than simpler models that extrapolate sampling data over larger areas. The methods used to estimate population size are applicable to other cryptic seabird species, especially those that live or breed in burrows. It is important to establish accurate baseline estimates of the populations of common seabird species against which to determine responses to perturbations and management interventions.

Long-term trends in the population size and breeding success of emperor penguins at the Taylor Glacier colony, Antarctica

The population size of emperor penguins at the land-based Taylor Glacier colony was monitored over 54 years from 1957 to 2010 by intermittent ground counts from 1957 to 1975 and annual photographic counts from 1988 to 2010 of males attending the colony in winter and chicks in early summer. The breeding population in the early years averaged 3,684 ± 492 pairs compared with 2,927 ± 320 pairs from 1988–2010, a reduction of 20.5 %. The exact timing and magnitude of the change is unknown because there was a 13-year gap between the end of the historical counts and start of the contemporary counts. From 1954 to 2010 no real or inferred warming event that may have been linked to the decrease was evident at Australia’s Mawson station, 95 km from Taylor Glacier colony. From 1988 to 2010, variation in breeding population size and breeding success were not related to variation in the distance between the colony and open water. In this period, the number of pairs breeding fluctuated annually and overall showed signs of a gradual decrease. The Taylor Glacier colony is one of only three emperor penguin colonies where populations have been monitored in winter over the long term. Given the threat of climate warming to the future of this ice-dependent species it is imperative that the annual monitoring programme at Taylor Glacier continues well into the future.

Greater sage-grouse sex ratios in Utah: Implications for reporting population trends

Greater sage-grouse (Centrocercus urophasianus; sage-grouse) are a species of conservation concern throughout western North America. Obtaining valid population estimates is essential to understanding population trajectories and the effects of management. Counts of male sage-grouse attending leks during the breeding season are used directly as a population index or to estimate the breeding population size by assuming a detection probability and sex ratio. In the latter case, managers often assume a 2:1 female-biased ratio. However, this sex ratio has not been validated and may result in biased population estimates. We evaluated sex ratios at hatch, 42 days of age, and at harvest to determine if sex ratios were biased for sage-grouse in Utah. Sex ratios at hatch and at 42 days of age did not differ from parity. Harvest data suggested that sage-grouse may exhibit a slight female-biased sex ratio (1.458:1) in the fall. Wildlife management agencies should use caution when using lek count data to estimate population size if sex ratios have not been validated. © 2013 The Wildlife Society.

Experimental Effects of Temperature and Photoperiod on Synchrony of Gametogenesis and Sex Ratio in the European OysterOstrea edulis(Linnaeus)

Insufficient knowledge about physiological processes underpinning reproduction in the European flat oyster, Ostrea edulis (Linnaeus), presents a number of unique challenges when designing a large-scale selective breeding program for hatchery production. The European flat oyster is a larviparous, protandric hermaphrodite wherein asynchronous spawns and variable sex ratios can lead to loss of genetic diversity and inbreeding depression within hatchery populations as a result of disproportionate gametic contributions in mass matings. A better understanding of O. edulis physiology in relation to environmental factors has the potential to improve hatchery processes for synchronization of gametogenesis, thus increasing fertilization potential and maximizing breeding population size of broodstock. This study sought to determine whether specific conditioning procedures—notably, manipulation of temperature and photoperiod—could be used to improve synchrony of gametogenesis and predictability of sex ratios in O. edulis. Two trials of accelerated yearly variations of temperature and photoperiod were conducted to uncouple the specific role of these factors in the timing of gametogenesis and sex of gametes over several spawning cycles. Histological analysis and quantitative analysis of gonad using a gonad filling index allowed for determination of sex ratios and staging of gametogenesis. Temperature was a controlling factor, although experimental results suggested that the effects of photoperiod, uncoupled from temperature, had no effect on the timing or rate of gametogenesis, or on sex ratios during a breeding season. A better understanding of factors affecting sex ratio and synchrony in timing of gamete release will allow for improved conditioning and broodstock handling protocols in the selective breeding of O. edulis.

Cost analysis of the application of marker-assisted selection in potato breeding

The primary aim of plant breeders is to develop new cultivars in order to improve productivity and to combat threats from pests and diseases. Recent advances in genomics have been recognised as providing important tools for plant breeders in the form of molecular genetic markers that can be used to tag genes of interest. However, the cost-effective use of marker technology is dependent on the nature and timing of the use of such markers. A conventional potato breeding programme typically creates a large breeding population and then employs phenotypic recurrent selection over a number of generations to identify superior genotypes. Marker-assisted selection (MAS) provides the advantage of being applicable at the seedling or an early generation stage. We have analysed the cost of MAS and compared it to conventional screening, then modelled the respective costs against the breeding population size of the generation in which they would be applied to determine whether MAS in the early generations of a potato breeding programme would be cost-effective. As various potato breeding programmes employ different selection rates in early generations, these rates have also been modelled to determine the effect. Our results indicate that MAS could be applied cost-effectively in the second clonal generation for all models currently employed in potato breeding.

Interactive effects of wildfire, forest management, and isolation on amphibian and parasite abundance

Projected increases in wildfire and other climate-driven disturbances will affect populations and communities worldwide, including host-parasite relationships. Research in temperate forests has shown that wildfire can negatively affect amphibians, but this research has occurred primarily outside of managed landscapes where interactions with human disturbances could result in additive or synergistic effects. Furthermore, parasites represent a large component of biodiversity and can affect host fitness and population dynamics, yet they are rarely included in studies of how vertebrate hosts respond to disturbance. To determine how wildfire affects amphibians and their parasites, and whether effects differ between protected and managed landscapes, we compared abundance of two amphibians and two nematodes relative to wildfire extent and severity around wetlands in neighboring protected and managed forests (Montana, USA). Population sizes of adult, male long-toed salamanders (Ambystoma macrodactylum) decreased with increased burn severity, with stronger negative effects on isolated populations and in managed forests. In contrast, breeding population sizes of Columbia spotted frogs (Rana luteiventris) increased with burn extent in both protected and managed protected forests. Path analysis showed that the effects of wildfire on the two species of nematodes were consistent with differences in their life history and transmission strategies and the responses of their hosts. Burn severity indirectly reduced abundance of soil-transmitted Cosmocercoides variabilis through reductions in salamander abundance. Burn severity also directly reduced C. variabilis abundance, possibly though changes in soil conditions. For the aquatically transmitted nematode Gyrinicola batrachiensis, the positive effect of burn extent on density of Columbia spotted frog larvae indirectly increased parasite abundance. Our results show that effects of wildfire on amphibians depend upon burn extent and severity, isolation, and prior land use. Through subsequent effects on the parasites, our results also reveal how changes in disturbance regimes can affect communities across trophic levels.

Population estimates of three vulture species in Kruger National Park, South Africa

Vultures are globally threatened, yet reliable population data on these birds are few, thus measuring their response to change is difficult. Kruger National Park (KNP) in South Africa is an important stronghold for many avian species, particularly vultures. In this study we generate population estimates for three vulture species in KNP using two plotless density estimators (PDE): a distance estimator based on nearest-neighbour distance and T-square sampling. We flew aerial censuses over large (c. 3 500 km2) sample areas in two ecogeographically separate parts of KNP and counted vulture nests visible within predetermined transects. In total 416 White-backed Vulture Gyps africanus, 22 Lappet-faced Vulture Torgos tracheliotos and 24 White-headed Vulture Trigonoceps occipitalis nests were recorded. The nearest-neighbour distance PDE performed poorly, and we used a T-square PDE calibrated with aerial survey counts to extrapolate across KNP and estimate breeding population sizes. There are an estimated 904 (95% CI±162) pairs of African White-backed Vultures, 78 (95% CI±18) pairs of Lappet-faced Vultures and 60 (95% CI±13) pairs of White-headed Vultures in KNP. These results provide a basis for investigating how large vultures respond to ecosystem change and understanding their resilience within a broader environmental change scenario.

Genomic prediction of trait segregation in a progeny population: a case study of Japanese pear (Pyrus pyrifolia)

BackgroundIn cross breeding, it is important to choose a good parental combination that has high probability of generating offspring with desired characteristics. This study examines a method for predicting the segregation of target traits in a progeny population based on genome-wide markers and phenotype data of parental cultivars.ResultsThe proposed method combines segregation simulation and Bayesian modeling for genomic selection. Marker segregation in a progeny population was simulated based on parental genotypes. Posterior marker effects sampled via Markov Chain Monte Carlo were used to predict the segregation pattern of target traits. The posterior distribution of the proportion of progenies that fulfill selection criteria was calculated and used for determining a promising cross and the necessary size of the progeny population. We applied the proposed method to Japanese pear (Pyrus pyrifolia Nakai) data to demonstrate the method and to show how it works in the selection of a promising cross. Verification using an actual breeding population suggests that the segregation of target traits can be predicted with reasonable accuracy, especially in a highly heritable trait. The uncertainty in predictions was reflected on the posterior distribution of the proportion of progenies that fulfill selection criteria. A simulation study based on the real marker data of Japanese pear cultivars also suggests the potential of the method.ConclusionsThe proposed method is useful to provide objective and quantitative criteria for choosing a parental combination and the breeding population size.

Preliminary evaluation of fruit traits and phytochemicals in a highbush blueberry seedling population

BACKGROUND:The fruit quality traits and the phytochemical content of blueberries are of increasing importance to researchers in the field of food and health and important breeding objectives. OBJECTIVE: The aim of this study was to gain preliminary information on parent’s performances and variation of the fruit traits and phytochemicals from a small breeding population. METHODS: The breeding population was from a 3× 4 factorial mating design, 120 seedlings in total. The fruit traits evaluated were weight, colour, pedicel scar size and firmness and the phytochemical composition included the total anthocyanin and phenolic contents and total antioxidant activity. RESULTS: Variation was found for all the traits studied in all families, with low genetic correlations between fruit traits, high correlations between phytochemicals and negative correlations between fruit weight and phytochemicals. CONCLUSIONS: Breeding population size was small and the lack of replication has influenced the statistical approach. From our observations we found ‘Hortblue Petite’ potentially an excellent parent for phytochemical traits.

Nesting Common Eider (&lt;i&gt;Somateria mollissima&lt;/i&gt;) Population Quintuples in Northwest Greenland

Common eider (Somateria mollissima) populations in Greenland severely declined throughout the 20th century. As a result, in 2001, harvest regulations were changed and the length of the hunting season was reduced. Recent data suggest that these changes have been successful, and population regrowth is occurring. In the Avanersuaq District, northwest Greenland, only one systematic survey quantifying the number of nesting eiders had previously been conducted, in 1997 and 1998. Although this district had historically been identified as having the largest number of breeding eiders in Greenland, the 1997–98 survey results showed a relatively small estimated population of 5000 pairs. However, it is not known to what extent changes in hunting regulations have affected nesting abundance in this area. Therefore, the Avanersuaq District was systematically resurveyed during the 2009 breeding season, approximately 11 years after the previous survey. These results showed that the population had increased to 5.4 times its 1997–98 size, with an annual compounded growth rate of 15.3%. On a single island, nearly 4500 active nests were observed. Five islands had more than 2600 nests each and comprised 75% of the total nests counted. Along with historical information to account for additional nesting habitat not surveyed, the observed population growth rate from this study suggests that the overall Avanersuaq common eider breeding population size ranges from 25 000 to 30 000 pairs, or roughly half of the total estimated West Greenland breeding population. Despite the significance of the Avanersuaq District as a breeding area for common eiders, we have only limited information about this population. The effects of recent extensions of the hunting season on this population are also unknown, and the only wintering location information is based on a few individuals banded in the 1920s and 1940s. Additional research on migratory movements is suggested before any further changes are made to hunting regulations.