Parasite egg recognition based on multicomponent cues by green-backed tits (Parus monticolus)

Egg recognition and rejection is a common and effective anti-parasitism adaptation in bird hosts. Hosts reject alien eggs using recognition signals such as egg ground color and maculation. Green-backed tits ( Parus monticolus) have a highly developed capability for recognizing parasite eggs, but the cues used for egg recognition are unclear. We combined avian visual perceptual modeling and field experiments to explore the effects of egg ground color and maculation on the recognition of parasite eggs. P. monticolus uses a multi-cue with possible hierarchical mechanism for egg recognition. The mechanism of egg recognition in P. monticolus appears to be a specific adaptation to the phenotypes of eggs laid by local brood parasites.

Delayed timing of breeding attempts, but not time lost to nest construction, reduces the annual reproductive output of the Eastern Phoebe (Sayornis phoebe)

For many birds, nest construction is a costly aspect of parental care, trading finite energetic resources between parental care and self-maintenance. For multi-brooded organisms with short breeding seasons, such as migratory passerines, repeated nest construction could be especially costly if the activity delays the onset of breeding attempts. Earlier studies on passerines that reuse nests between breeding seasons suggested that time lost to initial nest construction reduces seasonal reproductive output. However, costs associated with building new nests between breeding attempts, within the same breeding season, have largely been ignored. Here, we experimentally removed first nests, after fledging or failing, of Eastern Phoebes ( Sayornis phoebe), to evaluate how the annual onset of breeding and nest construction between breeding attempts affected parental investment into second attempts. We found that first egg laying date negatively predicted the probability of second breeding attempts, but experimental treatment (first nest removal vs. control) did not. Neither first egg laying date nor treatment statistically influenced any of the reproductive traits in second breeding attempts (clutch size, nestling body condition, and nestling growth rate). We conclude that in this species, second breeding attempts are limited by the initial onset of seasonal reproduction, and not by time lost to nest construction between breeding attempts.

Composition of nests constructed by species in the Motacillidae, Sylviidae and Prunellidae

Bird nests can be complex bio-engineered structures constructed from a range of materials to provide a site for incubation, and in many species chick rearing. Reports of the materials used in nest walls and cup linings are typically qualitative and do not assist in understanding the functional properties of the structure as a whole. This paper provides size and composition data for nests from four species of the Motacillidae family: the meadow pipit ( Anthus pratensis), pied wagtail ( Motacilla alba), grey wagtail ( Motacilla cinerea), and the yellow wagtail ( Motacilla flava), three species of the Sylviidae family: willow warbler ( Phylloscopus trochilus), Eurasian reed warbler ( Acrocephalus scirpaceus) and Eurasian blackcap ( Sylvia atricapilla), and the dunnock ( Prunella modularis) of the Prunellidae family. Three hypotheses were tested: do nest dimensions correlate with body mass? Is it possible to distinguish among species based on their nest composition; and for individual species? Is it possible to distinguish between the cup lining and outer nest wall based on the materials used in construction? Nest composition and size varied among species although the degree of intra-specific variation was different. Size of a nest was unrelated to average female adult body mass. Composition relied on similar types of materials but in differing quantities between species. It was possible to distinguish among species in terms of nest construction, and between the cup lining and the outer nest, on the basis of at least one of the component materials. By providing quantitative data on composition, it may be possible in the future to understand better the structural, insulative and hydrological properties of the nest. Such information will be invaluable as we begin to develop an understanding of the factors that have driven evolution of nest architecture.

An attempt to determine the size of the Common Barn-owl’s (Tyto alba) hunting area based on its prey composition

The relative abundance of small mammal species detected from Common Barn-owl pellets reflects the landscape structure and habitat pattern of the owl’s hunting area, but it is also affected by the size of the collected pellet sample and the size of the supposed hunting area. The questions arise: how many pellets should be collected and analyzed as well as how large hunting area should be taken into consideration in order to reach the best correspondence between the owl’s prey composition and the distribution of habitats preferred by small mammals preyed in supposed hunting areas? For this study, we collected 1045 Common Barn-owl pellets in a village in southern Hungary. All detected small mammal species were classified into functional groups (guilds) preferring urban, open, forest and wetland habitats. The proportion of functional groups was compared to the proportion of these habitats around the pellet collection site within circles of one, two, and three km radius. Saturation curves showed that at least 300 pellets or ca. 600 mammalian remains are required for the detection of the 19 small mammal species. The share of small mammals detected in the prey and their functional groups according to their habitat preference showed an increasing consistency with the distribution of real habitats in the potential hunting area of a radius of 3 km around the owl’s breeding or resting place.

How food supply in rubbish dumps affects the breeding success and offspring mortality of cattle Egret Bubulcus ibis?

The objective of this study was to evaluate the effect of food supply in garbage dumps on the reproductive fitness of Cattle Egret Bubulcus ibis and offspring losses. A total of 236 nests were monitored during two distinct periods of 2 years for each: 146 nests during a period without food supply in dumps (1998–1999) and 90 with food supply in dumps (2007–2008). The study was carried out in the colony of El-Kseur in the Lower Soummam Valley (northeast Algeria). For the entire study period, the mean of clutch size, average number of hatched chicks, productivity, and breeding success varied significantly between years (Kruskal–Wallis test: p < .05). Also, the average calculated losses for eggs, chicks, and total offspring vary significantly (Chi2 test: p > .0001). The clutch size and the number of hatched chicks per nest were highest during the period with food supply in garbage dump (respectively: 3.46 ± 0.86; 2.85 ± 1.11), compared to the period when cattle egrets feed in natural or agricultural habitats (3.04 ± 0.87; 2.54 ± 1.03). However, productivity and breeding success were highest during the period without food supply (respectively: 2.11 ± 1.16 fledging’s/nest; 0.70 ± 0.35) than in the period with food supply (1.14 ± 0.91; 0.35 ± 0.30). While egg losses were substantially similar between the two study periods, chick’s mortality (59.9%) and total offspring losses (36.7%) were higher during the period with food supply. The generalized linear mixed model (GLMM) analysis indicated a large negative effect of food supply in dumps on the productivity, on the chick’s losses; and a positive effect on the total offspring losses ( p < .001). Also, feed in dump garbage revealed a significant negative effect on the breeding success linear mixed model (LMM, p = .01). However, no significant effects (GLMM, p > .05) of food supply in dumps were noted on average clutch size, the mean number of hatched chicks per nest, and egg losses.

Phylogenetic relationships and genetic variations among cinereous vultures Aegypius monachus in South Korea

Mature individuals of the cinereous vulture, Aegypius monachus, number 15,600–21,000 birds worldwide and population size of the bird has been in decline due to poisoned baits and the decreasing availability of food. Approximately 12–16% of the global population of cinereous vultures spend their winters in Korean regions that are hence important areas. In this study, the population structure and genetic diversity of the cinereous vulture in South Korea were evaluated to clarify the relationships between the Mongolian and South Korean populations with genetic diversity assessed using mitochondrial DNA (mtDNA) and microsatellite markers. In the South Korean population, two unique haplotypes (Hap8 and Hap9) were newly discovered in their mtDNA, with three polymorphic sites and low-level genetic diversity. Most of the cinereous vultures in South Korea were represented by a single haplotype, Hap8, and analyses of phylogenetic trees and the haplotype network illustrated that Hap8 was clustered in Lineage D (Mongolia). Notably, the other haplotype, Hap9, was only identified in one individual in South Korea with an unexpected clustering in Lineage C (Caucasus region, Armenia, Georgia, and Kazakhstan populations), which indicated that it might have been a vagrant bird. The microsatellite loci ( n = 21) isolated from South Korean cinereous vultures indicated comparatively lower genetic variation, with a K value of 1. These results indicate that the origin of the South Korean population is most likely from one source population of the Far Eastern cluster (Mongolian population), which was also supported by the outcome of mtDNA analysis. This study improves our understanding of the population structure and genetic diversity between the Mongolian and South Korean cinereous vulture populations.

Towards accurate and simple morphometric sex differentiation in Bonelli’s Eagle Aquila fasciata nestlings: Interpopulation variations and influence of growth conditions

Morphometric methods of sex differentiation may be cheap, simple, quick, and reliable alternatives to molecular approaches. However, there are still important uncertainties regarding the use of morphometric methods in birds, particularly regarding their applicability to different populations and environmental conditions. Between 2004 and 2019, we sampled 245 Bonelli´s Eagle Aquila fasciata nestlings, 197 from nests in Catalonia (northeastern Spain) and Andalusia (southeastern Spain) and 56 that were partially or totally raised in captivity. Our objective was to develop morphometry-based sexing methods for Bonelli’s Eagle nestlings that can be applied in situ to different subpopulations and growth conditions. We recorded up to nine measures related to nestling body mass, bill, tarsus, and claw length. Tail and wing length were used to control for the age of nestlings, and all individuals were sexed genetically. We found important morphometric differences between the two natural subpopulations. According to our discriminant analyses, body mass and claw length were the most discriminant variables, both in wild and captivity conditions. Differences between sexes were more prominent during the flight feathers’ growing period. Feeding ad libitum in captivity conditions led to larger nestlings and reduced between-sexes differences. We provide different models for sexing Bonelli’s Eagle nestlings that can be applied according to the studied geographic location, growth conditions (wild versus captive), and balance between accuracy and simplicity. Overall, our findings highlight that extrapolating sex discriminant functions to different subpopulations and growth conditions may be risky.

Novelty at dawn: Exploration, low neophobia and crepuscular activity in a wild Common Buzzard (Buteo buteo)

Raptor cognition has received limited research attention, despite the importance of comparative investigations for reconstructing the evolution of complex cognition. Field studies provide essential ecological context for cognition in the natural habitat, although this approach is often challenging due to extensive procedures involved in cognitive testing. One predisposition suggested to contribute to problem-solving behaviour is the response to novel stimuli. In this pilot study, a novel object test was conducted on an outdoor feeding platform to assess the neotic responses of a single wild free-ranging Common Buzzard ( Buteo buteo), a generalist/opportunist diurnal predator species. Additionally, data on its daily activity were collected. As predicted, the subject expressed low neophobia and some exploratory behaviours. Interestingly, it repeatedly arrived on the platform in low light conditions. This study highlights the influence of foraging ecology on cognitive predispositions and offers a field method for research on raptor cognition.

Population status and distribution of the critically endangered Indian Courser (Cursorius coromandelicus) on Delft Island, Sri Lanka

The critically endangered Indian Courser ( Cursorius coromandelicus) is a rare resident bird species in Sri Lanka. This bird species is restricted to the northern avifaunal region of Sri Lanka, and even there it has been recorded from only a few locations. Thus, it is identified as one of the rarest birds in Sri Lanka. A 1-year study was conducted to investigate Indian Courser population and their distribution within the Delft Island from 5th of January to 20th of December 2020. Ten (10) randomly selected points were investigated in this study. Of the 10 sampling points, the Indian Courser was observed within three (03) sampling points year around while several sightings were recorded in points 8, and 9 during 3 months of the year. Their abundance significantly varied among sampling locations (one-way ANOVA, F = 15.04, p < .05). The maximum number of individuals recorded was 18 ± 4.64 in December and the minimum number was 4 ± 4.64 during the non-migrant season. Although most of the area in the island is covered with dry grasslands, their distribution in Delft is largely confined to a few grassland patches where human activities are minimum. Hunting, egg collection, and trampling of their nest by the Delft ponies (feral horses) can be identified as the main threats of this species. It is of utmost importance to immediately implement holistic conservation measures to save this critically endangered bird as Delft is the only known location where a viable resident population of Indian Courser is found.