29,757 research outputs found

    Colorful eggs and plumage in birds: ecological drivers of color patterns filtered through bird visual systems

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    Birds use color signals for multiple functions, including attracting and choosing mates, recognizing their own offspring from those of unrelated conspecifics or obligate brood parasites, foraging for different food resources, or hiding from predators. Importantly, an integrative approach is necessary to effectively address how and why birds have evolved to perceive and produce extravagant colors and patterns. Color signal information content, color perception, and cognitive decision rules underlying behaviors in response to color are equally important. The goal of my doctoral dissertation is to understand how birds use colorful signals, including colorful eggs and feathers, to make decisions that affect their fitness. Chapter 1 discusses the implications of categorical perception of color in animals and emphasizes the importance of ecological context in shaping how animals categorize stimuli. Chapter 2 thoroughly tests American robin (Turdus migratorius) perception and categorization of egg color, egg size, and egg pattern features when deciding whether to accept or reject a foreign egg present in the nest. Chapter 3 experimentally tests how American robin color perception and visual acuity integrate when robins view and decide to reject foreign eggs from their nests. Chapter 4 investigates how brood parasite host species phenotypes, shaped by foraging ecology, may constrain or facilitate host species ability to recognize and reject brood parasite eggs from their nests. Chapter 5 assesses how ecological pressures reducing the time available and increasing the effort necessary to find a compatible mate may promote the evolution of plumage sexual dichromatism in true thrushes (Turdus spp.). Overall, results from this dissertation demonstrate that, respectively, colorful eggs and plumage likely serve to facilitate recognition of offspring and mates.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste

    Evaluation of economic loss caused by Indian crested porcupine (Hystrix indica) in agricultural land of district Muzaffarabad, Azad Jammu and Kashmir, Pakistan

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    The Indian crested porcupine (Hystrix indica) is a vertebrate pest of agricultural lands and forest. The study was aimed to report the damage to local crops by the Indian crested porcupine (Hystrix indica) in the Muzaffarabad District. A survey was conducted to identify the porcupine-affected areas and assess the crop damage to the local farmers in district Muzaffarabad Azad Jammu and Kashmir (AJK) from May 2017 to October 2017. Around 19 villages were surveyed, and a sum of 191 semi-structured questionnaires was distributed among farmers. Crop damage was found highest in village Dhanni where a porcupine destroyed 175 Kg/Kanal of the crops. Regarding the total magnitude of crop loss, village Danna and Koomi kot were the most affected areas. More than half (51.8%) of the respondents in the study area suffered the economic loss within the range of 101-200,and(29.8, and (29.8%) of the people suffered losses in the range of 201-300 annually. Among all crops, maize (Zea mays) was found to be the most damaged crop ranging between 1-300 Kg annually. In the study area, porcupine also inflicted a lot of damages to some important vegetables, including spinach (Spinacia oleracea), potato (Solanum tuberosum) and onion (Allium cepa). It was estimated that, on average, 511Kg of vegetables are destroyed by porcupine every year in the agricultural land of Muzaffarabad. It was concluded that the Indian crested porcupine has a devastating effect on agriculture which is an important source of income and food for the local community. Developing an effective pest control strategy with the help of the local government and the Wildlife department could help the farmers to overcome this problem

    Acoustic activity of bats at power lines correlates with relative humidity: a potential role for corona discharges

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    With the ever-increasing dependency on electric power, electrical grid networks are expanding worldwide. Bats exhibit a wide diversity of foraging and flight behaviours, and their sensitivity to anthropogenic stressors suggests this group is very likely to be affected by power lines in a myriad of ways. Yet the effects of power lines on bats remains unknown. Here we assessed the responses of insectivorous bats to very high voltage power lines (VHVPL; greater than 220 kV). We implemented a paired sampling design and monitored bats acoustically at 25 pairs, one pair consisting of one forest edge near to VHVPL matched with one control forest edge. Relative humidity mediates the effects of power lines on bats: we detected bat attraction to VHVPL at high relative humidity levels and avoidance of VHVPL by bats at low relative humidity levels. We argue that the former could be explained by insect attraction to the light emitted by VHVPL owing to corona discharges while the latter may be owing to the physical presence of pylons/cables at foraging height and/or because of electromagnetic fields. Our work highlights the response of bats to power lines at foraging habitats, providing new insight into the interactions between power lines and biodiversity

    Longitudinal associations of concurrent falls and fear of falling with functional limitations differ by living alone or not

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    BackgroundFalls and fear of falling (FOF) are independent risk factors for functional limitations in older adults. However, the combined effect of falls and FOF on functional limitations and the moderating role of living alone or not is unclear. We aimed to examine (1) the independent and combined effect of falls and FOF on functional limitations in older adults and (2) whether living alone moderates these associations.MethodsWe used data from the National Health and Aging Trends Study (NHATS) and included 5,950 U.S. community-dwelling older adults aged 65 and older from Round 1 (Year 2011) and Round 2 (Year 2012). Falls and FOF were ascertained by asking participants whether they had any falls in the last year and whether they had worried about falling in the previous month at R1. Assessed functional limitations included any difficulties with mobility, self-care, or household activities at R2. Poisson regression models were used to examine the longitudinal associations of falls and FOF with functional limitations and the moderation effects of baseline living alone.ResultsOf the 5,950 participants, 16.3% had falls only; 14.3% had FOF only; 14.3% had both, and 55.1% had neither at baseline. In the adjusted model, those who experienced concurrent falls and FOF in R1 had a higher risk of functional limitations at R2 than those with neither (Mobility: Incidence risk ratio [IRR] = 1.34, 95% CI: 1.24–1.45; Self-care: IRR = 1.18, 95% CI: 1.11–1.26; Household: IRR = 1.20, 95% CI: 1.11–1.30). Moreover, living alone significantly moderated the longitudinal associations of concurrent falls and FOF with mobility activity limitations.ConclusionThe findings suggest that strategies to improve falls and FOF together could potentially help prevent functional limitations. Older adults who live with others and have falls or FOF should receive interventions to promote their mobility activities

    Impact of polyester and cotton microfibers on growth and sublethal biomarkers in juvenile mussels

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    Anthropogenic microfibres are a prevalent, persistent and globally distributed form of marine debris. Evidence of microfibre ingestion has been demonstrated in a range of organisms, including Mytilus spp. (mussels), but the extent of any impacts on these organisms are poorly understood. This study investigates, for the first time, the effect of exposing juvenile mussels to polyester and cotton microfibres at environmentally relevant concentrations (both current and predicted future scenarios) over a chronic timescale (94 days). Sublethal biomarkers included growth rate, respiration rate and clearance rate. Mussels were exposed to polyester (median length 149 µm) and cotton (median length 132 µm) microfibres in three treatments: polyester (~ 8 fibres L−1), polyester (~ 80 fibres L−1) and cotton (~ 80 fibres L−1). Mussels exposed to 80 polyester or cotton microfibres L−1 exhibited a decrease in growth rate of 35.6% (polyester) and 18.7% (cotton), with mussels exposed to ~ 80 polyester microfibres L−1 having a significantly lower growth rate than the control population (P < 0.05). This study demonstrates that polyester microfibres have the potential to adversely impact upon mussel growth rates in realistic future scenarios, which may have compounding effects throughout the marine ecosystem and implications for commercial viability

    Unpredictable Needs are Associated with Lower Expectations of Repayment

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    Sometimes people help one another expecting to be repaid, while at other times people help without an expectation of repayment. What might underlie this difference in expectations of repayment? We investigate this question in a nationally representative sample of US adults (N = 915), and find that people are more likely to expect repayment when needs are perceived to be more predictable. We then replicate these findings in a new sample of US adults (N = 417), and show that people have higher expectations of repayment when needs are perceived to be more predictable because people assign greater responsibility to others for experiencing such predictable needs (e.g., needing money for utilities). This is consistent with previous work based on smaller-scale societies, which shows that the predictability of needs influences expectations of repayment. Our results also add to this previous work by (1) showing that the positive relationship between predictability of needs and expectations of repayment previously found in smaller-scale communities is generalizable to the US population, and (2) showing that attributions of responsibility partially mediate this relationship. This work shows that the predictability of needs and attributions of responsibility for that need are important factors underlying the psychology of helping in times of need

    Legal culture and climate change adaptation : an agenda for research

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    While climate change adaptation research has increasingly focused on aspects of culture, a systematic treatment of the role of legal culture in how communities respond to climate risk has yet to be produced. This is despite the fact that law and legal authority are implicated in most, if not all, of the ways in which actors seek to reduce the risks posed to communities by climate change. Using a scoping review methodology, this article examines the intersection of climate change adaptation and legal culture in existing research. Overall, we find that the significance of legal culture for adaptation actions has been under-explored. Yet, it is also clear that a focus on legal culture holds significant promise for our understanding of climate change adaptation. We set out a research agenda for the field, highlighting the ways in which a focus on legal culture may enrich existing key themes within climate change adaptation research. This article is categorized under: Policy and Governance > Governing Climate Change in Communities, Cities, and Regions Vulnerability and Adaptation to Climate Change > Institutions for Adaptation

    Climate change on rural women in East Africa: analysis of consequences and recommendations from a gendered approach

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    Climate change affects people and regions differently. The East Africa region is one of the most affected by the changes in the climate. There, women, especially the most marginalised and disadvantaged, are the most impacted, in many ways. Despite being the most heavily burdened, rural women are underrepresented and overlooked in tackling weather change. This can be changed by adopting a gender perspective that empowers women. This would allow them to improve their lives exponentially and to become key actors in mitigating and adapting to climate change effectively

    Winter mortality of a passerine bird increases following hotter summers and during winters with higher maximum temperatures

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    Climate change may influence animal population dynamics through reproduction and mortality. However, attributing changes in mortality to specific climate variables is challenging because the exact time of death is usually unknown in the wild. Here, we investigated climate effects on adult mortality in Australian superb fairy-wrens (Malurus cyaneus). Over a 27-year period, mortality outside the breeding season nearly doubled. This nonbreeding season mortality increased with lower minimum (night-time) and higher maximum (day-time) winter temperatures and with higher summer heat wave intensity. Fine-scale analysis showed that higher mortality in a given week was associated with higher maxima 2 weeks prior and lower minima in the current fortnight, indicating costs of temperature drops. Increases in summer heat waves and in winter maximum temperatures collectively explained 62.6% of the increase in mortality over the study period. Our results suggest that warming climate in both summer and winter can adversely affect survival, with potentially substantial population consequences
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