Potential negative effects of the installation of video surveillance cameras in raptors’ nests

López‐López, Pascual

doi:10.1038/s41598-022-26153-7

Cited by 3 publications

(1 citation statement)

References 54 publications

(85 reference statements)

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“…During this period, we used 10 × 42 binoculars (Olympus, Tokyo, Japan), a Swarovski 20–60× telescope (Swarovski Optik, Absam, Austria) and a Nikon camera with a 55–300 mm lens (Nikon, Tokyo, Japan). We estimated the age of nestlings whose parents did not have GPS transmitters using the feather development patterns, following the methodology described in [ 33 ] and used in similar studies of the same species [ 32 , 34 ]. For those juveniles whose parents had GPS transmitters, we knew the exact laying date, and, consequently, their age was precisely assessed [ 28 ].…”

Section: Methodsmentioning

confidence: 99%

Non-Invasive Sex Determination of Nestlings and Adult Bonelli’s Eagles Using Morphometrics

Estellés-Domingo

López‐López

2023

Animals

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Biometric analysis allows the sexing of most vertebrates, particularly birds. Birds of prey, and, especially, the Bonelli’s eagle (Aquila fasciata), show reverse sexual dimorphism (i.e., females are usually larger than males). In contrast to blood sampling, the use of morphometrics allows sex determination using a non-invasive method, and, therefore, it facilitates fieldwork. By means of a linear discriminant analysis of biometric variables, we obtained different equations that allow the sexing of nestlings and adult Bonelli’s eagles. We sampled 137 Bonelli’s eagles, 82 nestlings and 55 adults in eastern Spain during the period 2015–2022. The sexes obtained after linear discriminant analysis were compared with their molecular sexing. The validation procedure of the linear discriminant equations facilitated the reduction of the number of variables used and, consequently, optimised working time and sexing accuracy. After validation, some equations showed a 100% sexing efficiency for Bonelli’s eagles, particularly for adults. Our results showed that the variables with smaller overlap between the sexes were the lateral tarsus length and dorso-ventral tarsus length, particularly in nestlings. The rest of the variables showed some overlap between the sexes in both age classes. The results we obtained enable the sexing of juvenile and adult Bonelli’s eagles in the field using just these two measurements. Hence, this is an easy, accurate, quick and non-invasive method with multiple applications, including in studies on population dynamics, survival analysis or extinction risk assessments, which, ultimately, could contribute to the improvement of the conservation status of this endangered species.

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Section: Methodsmentioning

confidence: 99%

Non-Invasive Sex Determination of Nestlings and Adult Bonelli’s Eagles Using Morphometrics

Estellés-Domingo

López‐López

2023

Animals

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Laying date depends on territorial breeders’ age, climatic conditions and previous breeding success: a long-term study (2004–2021) with Bonelli’s eagle in Spain

López-Peinado,

López-López

2024

J Ornithol

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Adjustment of reproductive timing within the annual cycle is a crucial issue for both offspring and parents’ survival, and breeding success. Early laying date is closely related to successful breeding outcome and better survival. Obtaining long datasets on threatened long-lived species’ breeding performance can contribute to their conservation. Using field observations and telemetry information, here we analyse how laying date of an endangered long-lived raptor varies with nest characteristics, individual factors and climatic variables during an 18-year (2004–2021) study period in eastern Spain. To this end, we estimated how environmental and individual variables affect laying date. Our results showed that average laying date in our study area took place on February 17th. Laying date showed no trend during the study period. Nests placed in higher elevations showed delayed laying dates. Territories occupied by adults with previous successful experience and high brood size showed earlier laying dates. Current year laying date was highly correlated with previous year laying date. Colder territories delayed laying date and the minimum temperature of the previous December were negatively correlated to previous laying date. Our results highlight the importance of experienced birds able to adjust timing of reproduction to maximise biological fitness. High adult mortality allows sub-adults to settle as breeders and jeopardises species’ persistence. Therefore, the reduction of mortality of territorial birds is of the outmost importance to improve the conservation status of declining long-lived species such as the Bonelli’s eagle (Aquila fasciata).

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Breeders’ age, nest-site characteristics and climatic conditions but not density-dependent effects determine Bonelli’s Eagle breeding performance: A long-term study (2002–2021)

López-Peinado,

López-López

2023

Ornithological Applications

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The conservation of endangered species is a crucial topic in conservation biology due to the important ecological roles these species play in their respective ecosystems. Top predators are particularly vulnerable to the variation in environmental conditions. The Bonelli’s Eagle (Aquila fasciata) is a long-lived bird of prey that fulfills its role as a top predator in Mediterranean ecosystems, but its overall population has declined in the Iberian Peninsula in recent decades. As with other long-lived species, the Bonelli’s Eagle reaches its maximum fitness at maturity, highlighting the importance of assessing how intrinsic and extrinsic factors affect population dynamics over time. In this study, we conducted annual surveys of a Bonelli’s Eagle subpopulation in the eastern Iberian Peninsula from 2002 to 2021. Our results indicate that the large decline observed in the number of occupied territories, fledged chicks, and successful pairs is not due to negative density-dependent effects but rather influenced by various environmental and demographic factors. These factors include breeders’ age, nest-site characteristics, climatic conditions, and previous breeding costs. We found that productivity was higher in territories with high winter precipitation and temperatures, as well as in coastal areas, leading to earlier laying dates. Additionally, the presence of subadult individuals in the breeding pair decreased breeding performance. Interestingly, the variability in the number of fledglings in each territory was driven by previous breeding costs. Prioritizing efforts to mitigate adult mortality and conserve suitable habitats becomes imperative to halt the ongoing decline of this population and also to enhance productivity, ultimately facilitating the restoration of the species to previous population levels.

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Potential negative effects of the installation of video surveillance cameras in raptors’ nests

Cited by 3 publications

References 54 publications

Non-Invasive Sex Determination of Nestlings and Adult Bonelli’s Eagles Using Morphometrics

Non-Invasive Sex Determination of Nestlings and Adult Bonelli’s Eagles Using Morphometrics

Laying date depends on territorial breeders’ age, climatic conditions and previous breeding success: a long-term study (2004–2021) with Bonelli’s eagle in Spain

Breeders’ age, nest-site characteristics and climatic conditions but not density-dependent effects determine Bonelli’s Eagle breeding performance: A long-term study (2002–2021)

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