Effects of elevated nest box temperature on incubation behaviour and offspring fitness-related traits in the Collared Flycatcher Ficedula albicollis

Ambient temperature experienced by an animal during development or subsequently as an adult can affect many aspects of its behaviour and life-history traits. In birds, egg incubation is a vital component of reproduction and parental care. Several studies have suggested that environmental factors (such as nest microclimate) can influence the ability of incubating parents to maintain suitable conditions for embryo development. Here, we manipulated the developmental conditions of embryos through a modification of nest box thermal microclimate to investigate female incubation behaviour and its impact on offspring fitness-related traits in a wild population of the Collared Flycatcher (Ficedula albicollis). The temperature in experimental nests was increased using a heat-pack placed under the roof of a nest box, resulting in an average temperature increase of 2.5 ºC, which corresponds to projected climate change scenarios. We demonstrated that females from nests with elevated temperature spent less time in the nest box during egg incubation and had more off-bouts than females from control nests. Moreover, we found that offspring from the experimentally heated nests had larger body mass at fledging in comparison to the control ones. Our study indicates that nest microclimate during the incubation period affects female incubation behaviour and offspring quality, indicating that environmental variation in nest temperature early in ontogeny can have important and long-lasting fitness consequences.

To the reproduction biology of the Wryneck (Jynx torquilla Linnaeus, 1758) in artificial nests in Northeastern Ukraine

In many countries, the Jynx torquilla population has declined significantly. In Ukraine, the species is considered widespread, but remains poorly studied. Activities to attract birds to parks using artificial nests were carried out during 2004‒2021 in Northeastern Ukraine. The first time the J. torquilla was populated in artificial nests dates back to 2009. During 2019‒2021 4 cases of J. torquilla nesting in artificial nests were recorded. Among the studied territories, the population of J. torquilla in artificial nests was found in the territory of the regional landscape park (RLP) «Feldman Ecopark», NPP «Gomilshansky forests» near the village. Gaidary in Kharkov and the tract «Vakalovschina» near the village Vakalovschina in Sumy regions. In the Northeastern of Ukraine, the number of J. torquilla reaches 14,3±0,32 pairs/km2 in the oak forests of the NPP «Gomilshansky forests» near the village Gaidary, 7,2±0,14 pairs/km2 in the pine forests of the park near the village Zadonetske, 16,2±0,14 pairs/km2 in the «Vakalovschina» tract, 11,1±0,24 pairs/km2 in RLP «Feldman Ecopark». J. torquilla, as a typical hollow-hole, is able to inhabit artificial nests. On average, during 2004–2021, the arrival of the first individuals in the spring was recorded: 21.04 at an average daily temperature of 18° C in the oak grove of the NPP «Gomilshansky forests», 23.04 at a temperature of 17° C in the tract «Vakalovschina», on the territory RLP «Feldman Ecopark» ‒ 02.05 at a temperature of 17° C, 2020 is 05.05 at a temperature of 20° С. It has been proven that 12 days pass from the moment of arrival of birds to the laying of the first egg. The first eggs of birds in the conditions of Northeastern Ukraine, on average, for all years of research, were registered 02.05 in the oak grove of the NPP «Gomilshansky forestsп», 04.05 in the tract «Vakalovschina». On the territory of RLP «Feldman Ecopark» in 2019, the first egg was laid at 14.05 on the material of the nest of the collared flycatcher Ficedula albicollis (Temm., 1815); in 2020 ‒ 19.05. Average clutch size 8,3±0,5 (from 7 to 9). Egg sizes: length – 20,2±0,2 mm, width ‒ 15,1±0,1 mm, volume ‒ 1.4±0.1 mmᶾ, roundness index ‒ 74.7±0.3 %. On average, incubation lasts 13±0,2 days. On the territory of the NPP «Gomilshansky forests» near the village. Gaidary, chicks hatched at 14.05; in the tract «Vakalovschina» on 16.05, on the territory of the RLP «Feldman Ecopark» in 2019 the chicks hatched on 26.05, in 2020 ‒ 01.06. The hatching success was found to be 96,9 % (n=30), where the breeding success is 91,0 %.

Inter-individual variation in provisioning rate, prey size and number, and links to total prey biomass delivered to nestlings in the Collared Flycatcher (Ficedula albicollis)

Background In bird species where offspring growth and survival rely on parents’ food provisioning, parents can maximise their fitness by increasing the quantity and/or the quality of preys delivered to their offspring. Many studies have focused on inter-individual variation in feeding rate, yet this measure may not accurately reflect the total amount of food (i.e. energy) provided by parents if there is large variation in the quantity and quality of preys at each feeding. Here, we explored the relative role of individual (sex, age, body condition), breeding (hatching date, brood size) and environmental (temperature) factors on feeding rate, prey number, size and quality, and their contribution to total prey biomass delivered to the nestlings of 164 Collared Flycatcher (Ficedula albicollis) parents in 98 nests. Results Preys delivered to the nest were mainly larvae (53.6%) and flying insects (45.6%). Feeding rate increased with brood size and age, and was higher in males than females. Mean prey number decreased, but mean prey size increased, as the season progressed and parents feeding their brood with primary larvae brought more preys per visit. Relationships between feeding rate, mean prey number and size remained when taking into account the provisioning quality: parents brought either a large number of small prey or a small number of larger items, and the force of the trade-offs between feeding rate and mean prey number and size depended on the quality of the provisioning of the parents. Whatever the percentage of larvae among preys in the provisioning, the variance in total prey biomass was foremost explained by feeding rate (65.1% to 76.6%) compared to mean prey number (16.4% to 26%) and prey size (2.7% to 4%). Conclusions Our study shows that variation in feeding rate, prey number, size, but not quality (i.e. percentage of larvae), were influenced by individual factors (sex and age) and breeding decisions (brood size and timing of breeding) and that, whatever the provisioning strategy adopted, feeding rate was the best proxy of the total biomass delivered to the nestlings.

Automatic bird song and syllable segmentation with an open-source deep-learning object detection method – a case study in the Collared Flycatcher (Ficedula albicollis)

The bioacoustic analyses of animal sounds result in an enormous amount of digitized acoustic data, and we need effective automatic processing to extract the information content of the recordings. Our research focuses on the song of Collared Flycatcher (Ficedula albicollis) and we are interested in the evolution of acoustic signals. During the last 20 years, we obtained hundreds of hours of recordings of bird songs collected in natural environment, and there is a permanent need for the automatic process of recordings. In this study, we chose an open-source, deep-learning image detection system to (1) find the species-specific songs of the Collared Flycatcher on the recordings and (2) to detect the small, discrete elements so-called syllables within the song. For these tasks, we first transformed the acoustic data into spectrogram images, then we trained two deep-learning models separately on our manually segmented database. The resulted models detect the songs with an intersection of union higher than 0.8 and the syllables higher than 0.7. This technique anticipates an order of magnitude less human effort in the acoustic processing than the manual method used before. Thanks to the new technique, we are able to address new biological questions that need large amount of acoustic data.

Digit ratio predicts the number of lifetime recruits in female collared flycatchers

The early environment in which an organism grows can have long-lasting impacts on both its phenotype and fitness. However, assessing this environment comprehensively is a formidable task. The relative length of the second to the fourth digit (2D : 4D) is a broadly studied skeletal trait that is fixed for life during ontogeny. 2D : 4D has been shown to indicate various early effects including the perinatal steroid milieu in both humans and non-human animals. However, the fitness relevance of the early effects indicated by 2D : 4D remains unknown. Here, we investigated hindlimb 2D : 4D and measures of lifetime performance in wild collared flycatcher ( Ficedula albicollis ) females. We found that females with higher 2D : 4D had a greater number of recruiting offspring to the breeding population. This was the case despite the fact that such females did not lay more eggs or breed more frequently during their reproductive life. Our results support the suggestion that 2D : 4D, known to be a retrospective marker of perinatal development, positively associates with female quality in the collared flycatcher.