Presence of the cloud cover and elevation angle of the sun affect measurements of eggshell coloration and patterning obtained from calibrated digital images

Szala, Klaudia; Tobółka, Marcin; Surmacki, Adrian

doi:10.1002/ece3.10170

Cited by 4 publications

(2 citation statements)

References 81 publications

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“…Color‐calibrated photography allows for relatively cheap and fast acquisition of spatio‐chromatic information within the environment, while visual modeling allows for the measurement of achromatic and opponent colors for different observer visual systems (Stevens et al, 2007 ; van den Berg et al, 2020 ). As the lighting environment was highly variable due to changes in solar angle and weather, all photos were taken with a 1 m 2 pop‐out NEEWER diffuser sheet at times greater than 2 h from dawn and dusk to prevent patterns from shadows changing the luminance and color measurements of the clutches and their backgrounds (Duarte et al, 2018 ; Szala et al, 2023 ; Troscianko, Wilson‐Aggarwal, Stevens, & Spottiswoode, 2016 ). Photographs were converted to standardized multispectral images using the “generate multispectral image” function within the MICA toolbox v2.2.2 for ImageJ (Schneider et al, 2012 ; Troscianko & Stevens, 2015 ; van den Berg et al, 2020 ).…”

Section: Methodsmentioning

confidence: 99%

“…As the lighting environment was highly variable due to changes in solar angle and weather, all photos were taken with a 1 m 2 pop-out NEEWER diffuser sheet at times greater than 2 h from dawn and dusk to prevent patterns from shadows changing the luminance and color measurements of the clutches and their backgrounds (Duarte et al, 2018;Szala et al, 2023;. Photographs were converted to standardized multispectral images using the "generate multispectral image" function within the MICA toolbox v2.2.2 for ImageJ (Schneider et al, 2012;Troscianko & Stevens, 2015;van den Berg et al, 2020).…”

Section: D Scanning and Calibrated Photographymentioning

confidence: 99%

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Habitat geometry rather than visual acuity limits the visibility of a ground‐nesting bird's clutch to terrestrial predators

Hancock,

Grayshon,

Burrell

et al. 2023

Ecology and Evolution

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The nests of ground‐nesting birds rely heavily on camouflage for their survival, and predation risk, often linked to ecological changes from human activity, is a major source of mortality. Numerous ground‐nesting bird populations are in decline, so understanding the effects of camouflage on their nesting behavior is relevant to their conservation concerns. Habitat three‐dimensional (3D) geometry, together with predator visual abilities, viewing distance, and viewing angle, determine whether a nest is either visible, occluded, or too far away to detect. While this link is intuitive, few studies have investigated how fine‐scale geometry is likely to help defend nests from different predator guilds. We quantified nest visibility based on 3D occlusion, camouflage, and predator visual modeling in northern lapwings, Vanellus vanellus, on different land management regimes. Lapwings selected local backgrounds that had a higher 3D complexity at a spatial scale greater than their entire clutches compared to local control sites. Importantly, our findings show that habitat geometry—rather than predator visual acuity—restricts nest visibility for terrestrial predators and that their field habitats, perceived by humans as open, are functionally closed with respect to a terrestrial predator searching for nests on the ground. Taken together with lapwings' careful nest site selection, our findings highlight the importance of considering habitat geometry for understanding the evolutionary ecology and management of conservation sites for ground‐nesting birds.

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Section: Methodsmentioning

confidence: 99%

Section: D Scanning and Calibrated Photographymentioning

confidence: 99%

Habitat geometry rather than visual acuity limits the visibility of a ground‐nesting bird's clutch to terrestrial predators

Hancock,

Grayshon,

Burrell

et al. 2023

Ecology and Evolution

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Machine learning outcompetes human assessment in identifying eggs of a conspecific brood parasite

Hughes,

Mari,

Troscianko

et al. 2024

Preprint

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Avian brood parasitism provides an exceptional system for studying coevolution. While conspecific brood parasitism (CBP) is more common than interspecific parasitism, it is less studied due to the challenge of detecting parasitic eggs, which closely resemble those of the host. Although molecular genotyping can accurately detect CBP, its high cost has led researchers to explore egg appearance as a more accessible alternative. Barn swallows (Hirundo rustica) are considered conspecific brood parasites, but identifying parasitic eggs has traditionally relied on human visual assessment. Here, we used UV-visible photographs of non-parasitized barn swallow clutches and simulated parasitism to compare the accuracy of human assessment with automated methods. In two games, participants and models identified parasitic eggs from six or two options. While humans performed better than chance (72% and 87% accuracy), they still made significant errors. In contrast, the automated supervised model was far more reliable, achieving 95% and 97% accuracy. We think that the model outperformed humans due to its ability to analyse a broader range of visual information, including UV reflectance, which humans cannot perceive. We recommend using supervised models over human assessment for identifying conspecific parasitic eggs and highlight their potential to advance research on evolution of egg colouration.

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The difficult challenge of accurately recording iris colour in birds revealed through the lens of specimens of Australia's Spinifex Pigeon (Geophaps plumifera)

Joseph,

Drew,

Wilson

et al. 2023

Ibis

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Museum collections of birds are a key source of data on the colours of ‘soft parts’, e.g. legs, feet, bill (maxilla, mandible), wattles, periocular skin and, our focus here, the iris of the eye. However, subjective descriptions of soft parts' colours have long plagued their use, whether in research or in illustrations of birds. We document a case where reasonable doubt about the accuracy of iris colour recorded more than 50 years ago in several taxonomically important series of specimens of the Australian Spinifex Pigeon Geophaps plumifera is probably unresolvable. This doubt clouds the downstream use of the specimens in a complete understanding of geographical and temporal variation, and taxonomy. We discuss how ornithologists may apply methods now readily available that will enable more rigorous recording of soft parts' colours, despite many valid limitations. This especially applies in situations where existing knowledge dictates care, such as in already known zones of taxonomic intergradation or when colours known to be unusual and unexpected are seen.

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Presence of the cloud cover and elevation angle of the sun affect measurements of eggshell coloration and patterning obtained from calibrated digital images

Abstract: Over the past few decades, there has been a growing interest in the pigmentation of avian eggshells. Many functions have been proposed to explain the vast diversity of this feature. Among them,

Cited by 4 publications

References 81 publications

Habitat geometry rather than visual acuity limits the visibility of a ground‐nesting bird's clutch to terrestrial predators

Habitat geometry rather than visual acuity limits the visibility of a ground‐nesting bird's clutch to terrestrial predators

Machine learning outcompetes human assessment in identifying eggs of a conspecific brood parasite

The difficult challenge of accurately recording iris colour in birds revealed through the lens of specimens of Australia's Spinifex Pigeon (Geophaps plumifera)

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