scholarly journals Observed heterospecific clutch size can affect offspring investment decisions

2011 ◽  
Vol 8 (3) ◽  
pp. 341-343 ◽  
Author(s):  
Jukka T. Forsman ◽  
Janne-Tuomas Seppänen ◽  
Inka L. Nykänen
Keyword(s):  
Clutch Size ◽  
Bird Species ◽  
Investment Decisions ◽  
Optimal Investment ◽  
Migratory Bird ◽  
Lifetime Reproductive Success ◽  
Egg Mass ◽  
Artificial Nests ◽  
Fine Tune

Optimal investment in offspring is important in maximizing lifetime reproductive success. Yet, very little is known how animals gather and integrate information about environmental factors to fine tune investment. Observing the decisions and success of other individuals, particularly when those individuals initiate breeding earlier, may provide a way for animals to quickly arrive at better breeding investment decisions. Here we show, with a field experiment using artificial nests appearing similar to resident tit nests with completed clutches, that a migratory bird can use the observed high and low clutch size of a resident competing bird species to increase and decrease clutch size and egg mass, accordingly. Our results demonstrate that songbirds can discriminate between high and low quantity of heterospecific eggs, and that social information can have long-term physiological consequences affecting reproductive strategies. Such behaviour may help animals to better adapt to changing environments and lead to convergent traits with competitors.

Conservation of the Swift Parrot Lathamus discolor ? management lessons for a threatened migratory species

2007 ◽  
Vol 13 (2) ◽  
pp. 111 ◽  
Author(s):  
Debbie Saunders ◽  
Raymond Brereton ◽  
Chris Tzaros ◽  
Mark Holdsworth ◽  
Rob Price
Keyword(s):  
Site Fidelity ◽  
Bird Species ◽  
Migratory Bird ◽  
Small Population ◽  
Assessment Process ◽  
Migratory Species ◽  
Conservation Assessment ◽  
Broad Distribution ◽  
Large Numbers

Conserving habitat for wide-ranging fauna species provides a challenge because impacts on these species tend to be dismissed based on the assumption that there is sufficient habitat in other areas of its range. This incremental loss of habitat is a serious conservation issue for a diversity of bird species. As knowledge of wide-ranging and migratory bird species increases, it often becomes evident that they select specific sites on a regular basis (i.e., the species exhibit site fidelity). Gaining a better understanding of site fidelity and selective habitat use for wide-ranging species is clearly important, but also extremely challenging. In this paper, challenges associated with conservation of the migratory and wide-ranging Swift Parrot Lathamus discolor are discussed as an example of how a recovery programme has aimed to address such conservation and management challenges. Despite the small population size (less than 2 500 birds), broad distribution (1 250 000 km2) and often cryptic nature, the implementation of the national recovery programme has been successful in the identification and protection of important habitats. This has been made possible by involving large numbers of volunteers who collect long-term sighting and habitat data over large areas, together with more detailed ecological research. This information is then used to inform the conservation assessment process and to improve habitat conservation throughout the range of the species.

scholarly journals Checklist of bird species in dharmadam estuary in kannur district of kerala

2021 ◽  
Vol 8 (1) ◽  
pp. 5-7
Author(s):  
Santhwana A ◽  
Venkitachalam R ◽  
Sridhu Prakash
Keyword(s):  
Seasonal Variation ◽  
Bird Species ◽  
Migratory Bird ◽  
Term Study ◽  
Long Term Study ◽  
Short Period ◽  
Near Threatened

A total of 20 bird species belongs to 7 orders and 11 families were recorded in Dharmadam estuary in Kannur district. The record of migratory bird Eurasian Curlew and two species near threatened birds within a short period of study and this record indicate that Dharmadam estuary may be attracting more number of migratory bird species. A long-term study is needed to understand the seasonal variation of the bird species in Dharmadam estuary in Kannur district.

The Pied Currawong's role in avian nest predation: a predator removal experiment

2001 ◽  
Vol 7 (3) ◽  
pp. 154 ◽  
Author(s):  
Graham R. Fulton ◽  
Hugh A. Ford
Keyword(s):  
Nest Predation ◽  
Bird Species ◽  
Artificial Nests ◽  
Predator Removal ◽  
Rural Landscapes ◽  
Before And After ◽  
Eucalypt Woodland ◽  
Avian Nest ◽  
High Level

Pied Currawongs Strepera graculina have been implicated as a major threat to the persistence of small passerines in urban and rural landscapes through their intense nest predation while raising their young. Pied Currawongs have recently increased in abundance and colonized new areas, due to the planting of exotic berry-bearing trees and shrubs. In association with habitat fragmentation, this may have intensified their predatory impact. We measured the rate of predation on 416 artificial nests, using quail and plasticine eggs, in a 240 ha remnant of eucalypt woodland. Nests were placed in one grid from which Pied Currawongs were removed and in one control grid. The level of predation was monitored before and after Pied Currawong removal. Overall, nest predation was extremely high with 91 % of all nests preyed upon in seven days. Moreover, nest predation decreased significantly following Pied Currawong removal, thus identifying them as significant nest predators. However, imprint evidence from plasticine eggs and the remains of real eggs indicate that other animals, particularly other birds, are also important predators. If this high level of nest predation is reflected in real nests and occurs over a number of years, it may lead to low recruitment of open-nesting birds at this site. If it occurs regionally, it could contribute to long term declines of these species. Our findings suggest that even quite large woodland fragments may be too small to sustain many declining bird species.

Price and subsidy under uncertainty: Real-option approach to optimal investment decisions on energy storage with solar PV

2021 ◽  
pp. 0958305X2199229
Author(s):  
Jingyu Qu ◽  
Wooyoung Jeon
Keyword(s):  
Renewable Energy ◽  
Energy Storage ◽  
Real Option ◽  
Financial Burden ◽  
Investment Decisions ◽  
Optimal Investment ◽  
Investment Incentives ◽  
Solar Pv ◽  
Increased Risk ◽  
Trigger Price

Renewable generation sources still have not achieved economic validity in many countries including Korea, and require subsidies to support the transition to a low-carbon economy. An initial Feed-In Tariff (FIT) was adopted to support the deployment of renewable energy in Korea until 2011 and then was switched to the Renewable Portfolio Standard (RPS) to implement more market-oriented mechanisms. However, high volatilities in electricity prices and subsidies under the RPS scheme have weakened investment incentives. In this study we estimate how the multiple price volatilities under the RPS scheme affect the optimal investment decisions of energy storage projects, whose importance is increasing rapidly because they can mitigate the variability and uncertainty of solar and wind generation in the power system. We applied mathematical analysis based on real-option methods to estimate the optimal trigger price for investment in energy-storage projects with and without multiple price volatilities. We found that the optimal trigger price of subsidy called the Renewable Energy Certificate (REC) under multiple price volatilities is 10.5% higher than that under no price volatilities. If the volatility of the REC price gets doubled, the project requires a 26.6% higher optimal investment price to justify the investment against the increased risk. In the end, we propose an auction scheme that has the advantage of both RPS and FIT in order to minimize the financial burden of the subsidy program by eliminating subsidy volatility and find the minimum willingness-to-accept price for investors.

scholarly journals Domain randomization-enhanced deep learning models for bird detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xin Mao ◽  
Jun Kang Chow ◽  
Pin Siang Tan ◽  
Kuan-fu Liu ◽  
Jimmy Wu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Continuous Monitoring ◽  
Bird Species ◽  
Training Data ◽  
Learning Models ◽  
Fine Grained ◽  
Bird Detection ◽  
Relationship Of ◽  
The Relationship

AbstractAutomatic bird detection in ornithological analyses is limited by the accuracy of existing models, due to the lack of training data and the difficulties in extracting the fine-grained features required to distinguish bird species. Here we apply the domain randomization strategy to enhance the accuracy of the deep learning models in bird detection. Trained with virtual birds of sufficient variations in different environments, the model tends to focus on the fine-grained features of birds and achieves higher accuracies. Based on the 100 terabytes of 2-month continuous monitoring data of egrets, our results cover the findings using conventional manual observations, e.g., vertical stratification of egrets according to body size, and also open up opportunities of long-term bird surveys requiring intensive monitoring that is impractical using conventional methods, e.g., the weather influences on egrets, and the relationship of the migration schedules between the great egrets and little egrets.

scholarly journals Temporal changes in reproductive success and optimal breeding decisions in a long-distance migratory bird

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Cynthia Reséndiz-Infante ◽  
Gilles Gauthier
Keyword(s):  
Reproductive Success ◽  
Clutch Size ◽  
Environmental Changes ◽  
Migratory Bird ◽  
Laying Date ◽  
Negative Consequences ◽  
Breeding Phenology ◽  
Additional Time ◽  
Long Distance ◽  
Seasonal Decline

AbstractMany avian migrants have not adjusted breeding phenology to climate warming resulting in negative consequences for their offspring. We studied seasonal changes in reproductive success of the greater snow goose (Anser caerulescens atlantica), a long-distance migrant. As the climate warms and plant phenology advances, the mismatch between the timing of gosling hatch and peak nutritive quality of plants will increase. We predicted that optimal laying date yielding highest reproductive success occurred earlier over time and that the seasonal decline in reproductive success increased. Over 25 years, reproductive success of early breeders increased by 42%, producing a steeper seasonal decline in reproductive success. The difference between the laying date producing highest reproductive success and the median laying date of the population increased, which suggests an increase in the selection pressure for that trait. Observed clutch size was lower than clutch size yielding the highest reproductive success for most laying dates. However, at the individual level, clutch size could still be optimal if the additional time required to acquire nutrients to lay extra eggs is compensated by a reduction in reproductive success due to a delayed laying date. Nonetheless, breeding phenology may not respond sufficiently to meet future environmental changes induced by warming temperatures.

Nest cameras do not affect nest survival in a meadow-nesting shorebird

2020 ◽  
pp. 1-10
Author(s):  
VOLKER SALEWSKI ◽  
LUIS SCHMIDT
Keyword(s):  
Nest Survival ◽  
Bird Species ◽  
Conservation Strategies ◽  
Survival Models ◽  
Northern Germany ◽  
Term Study ◽  
Long Term Study ◽  
Limosa Limosa ◽  
Study Sites

Summary Identifying the fate of birds’ nests and the causes of breeding failure is often crucial for the development of conservation strategies for threatened species. However, collecting these data by repeatedly visiting nests might itself contribute to nest failure or bias. To solve this dilemma, automatic cameras have increasingly been used as a time-efficient means for nest monitoring. Here, we consider whether the use of cameras itself may influence hatching success of nests of the Black-tailed Godwit Limosa limosa at two long-term study sites in northern Germany. Annually between 2013 and 2019, cameras were used to monitor godwit nests. In 2014 and 2019, nests were randomly equipped with cameras or not, and nest survival checked independently of the cameras. Nest-survival models indicated that survival probabilities varied between years, sites and with time of the season, but were unaffected by the presence of cameras. Even though predation is the main cause of hatching failure in our study system, we conclude that predators did not learn to associate cameras with food either when the cameras were initially installed or after they had been used for several years. Cameras were thus an effective and non-deleterious tool to collect data for conservation in this case. As other bird species may react differently to cameras at their nests, and as other sets of predators may differ in their ability to associate cameras with food, the effect of cameras on breeding success should be carefully monitored when they are used in a new study system.

scholarly journals First evidence for a latitudinal body mass effect in extant Crocodylia and the relationships of their reproductive characters

2020 ◽  
Vol 129 (4) ◽  
pp. 875-887
Author(s):  
Rebecca J Lakin ◽  
Paul M Barrett ◽  
Colin Stevenson ◽  
Robert J Thomas ◽  
Matthew A Wills
Keyword(s):  
Clutch Size ◽  
Body Mass ◽  
Linear Models ◽  
Incubation Temperature ◽  
Mass Effect ◽  
Distribution Patterns ◽  
Egg Mass ◽  
Phylogenetically Independent Contrasts ◽  
Extant Species ◽  
Female Body Mass

Abstract Relationships between distribution patterns and body size have been documented in many endothermic taxa. However, the evidence for these trends in ectotherms generally is equivocal, and there have been no studies of effects in crocodylians specifically. Here, we examine the relationship between latitudinal distribution and body mass in 20 extant species of crocodylians, as well as the relationships between seven important reproductive variables. Using phylogenetically independent contrasts to inform generalized linear models, we provide the first evidence of a latitudinal effect on adult female body mass in crocodylians. In addition, we explore the relationships between reproductive variables including egg mass, hatchling mass and clutch size. We report no correlation between egg mass and clutch size, upholding previously reported within-species trends. We also find no evidence of a correlation between measures of latitudinal range and incubation temperature, contrasting with the trends found in turtles.

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