Comparative studies of nestling growth typically rely on logistic growth-rate constants ( k ) to position species along the slow–fast life-history continuum, yet most analyses fit a single model without formally evaluating alternatives. Five deterministic growth models, Logistic, Gompertz, Richards, von Bertalanffy, and extreme-value function, were fitted to nestling mass, tarsus, and wing-chord data from eight bird species spanning a ∼250-fold body-mass range (∼20–5,500 g), including six Neotropical passerines and two non-passerines ( Megadyptes antipodes and Tachymarptis melba ). No single model was universally best-supported: four different models were selected across the eight species when ranked by information-theoretic criteria. In four of six Neotropical species, different morphometric traits favoured different best-fit models within the same species. Logistic k ranged from 0.078 d -1 in M. antipodes to 0.537 d -1 in Lanio versicolor , and interspecific growth-rate rankings shifted depending on which model was fitted. These results indicate that reliance on a single assumed growth model can bias parameter estimates and alter the comparative inferences drawn across species. We recommend reporting parameters from the best-supported model for each species–trait combination together with logistic k, so that results remain comparable with previous studies. Analyses used the open-source Nestling Growth App, and predictive checks compared information-criterion support with held-out performance in the two larger non-passerine datasets.
Parasite infection can impair avian nutrition and health and may contribute to population declines. The Asian Great Bustard ( Otis tarda dybowskii ) is a farmland-dependent wintering bird, yet its gastrointestinal parasite infection remains poorly studied, and the effects of agricultural habitat type on parasite community structure and infection intensity are unclear. We compared gastrointestinal parasite infection among wintering Great Bustards using fecal samples collected from four agricultural habitats. Eggs per gram of feces (EPG) were quantified using the McMaster counting method. Parasite shedding was highly aggregated (k < 1), indicating that parasite egg shedding was concentrated in a small number of samples with high EPG values. Total, nematode and cestode EPG values were significantly higher in the wheat + corn habitat than in the other habitats, whereas the wheat + alfalfa habitat showed the lowest overall EPG values. Nematode and cestode EPG values were significantly positively correlated (ρ = 0.62, p < 0.001), indicating positive covariation between nematode and cestode egg shedding. These findings provide baseline evidence for habitat restoration and low-intervention parasite risk management in farmland-dependent wintering birds.
Modern avian lineages evolved and radiated during the Cenozoic Era (66 Ma–present) following the end-Cretaceous extinction. Despite a wealth of isolated eggshells and nest structures, the global oological record remains unevenly studied. This review integrates the scattered literature on Cenozoic oological remains to produce the first comprehensive synthesis of their distribution, structure, palaeobiogeography, and palaeobiological significance. This record reconstructs temporal patterns in eggshell microstructure, nesting ecology, and biogeography. Methodological advances in microscopy, electron backscatter diffraction, isotopic geochemistry, and biomolecular preservation have enabled and refined taxonomic attributions and ecological interpretations of oological material. This synthesis highlights key gaps—particularly in Africa, Antarctica, and Oceania—and outlines research priorities aimed at linking palaeontology, molecular biology, conservation, de-extinction, and Earth-system sciences to better understand the evolutionary trajectory of avian reproduction. Furthermore, this evolving avian fossil record offers a critical foundation for reconstructing past ecosystems and informing efforts to conserve biodiversity into the future.
Hematological parameters are widely used as integrative indicators of physiological condition in birds. The Cabanis’s Ground Sparrow ( Melozone cabanisi ), a Costa Rican endemic species commonly associated with coffee plantations and semi-modified landscapes, lacks baseline hematological information, limiting the interpretation of blood-based health assessments. In this study, we established descriptive hematologic intervals for M. cabanisi and evaluated the influence of intrinsic biological factors—pectoral muscle condition and molt stage—on hematological variation. Free-ranging individuals were captured using mist nets and processed following standardized protocols. We quantified erythrocyte, leukocyte, and thrombocyte parameters, plasma protein concentration, and erythrocyte indices. Mean corpuscular hemoglobin concentration (MCHC) was selected as a focal parameter to assess physiological condition. Effects of muscle condition and molt stage on MCHC were evaluated using ART ANOVA and complementary bootstrapped linear models. Hematological values for M. cabanisi were broadly consistent with those reported for other small passerines, indicating conserved erythrocytic and immunological profiles. Pectoral muscle condition emerged as the strongest predictor of MCHC, with individuals in better somatic condition exhibiting significantly higher values. In contrast, molt stage did not show a significant main effect on MCHC in conservative analyses, and no interaction between muscle condition and molt stage was detected. These results provide the first hematological reference intervals for M. cabanisi and highlight body condition as a key intrinsic driver of hematological variation. The reference values presented here offer a robust physiological baseline for future ecological, conservation, and wildlife health studies involving this endemic Neotropical passerine.
Corvids such as magpies can cause economic losses and management conflicts in urban and agricultural landscapes, and repeated exposure can reduce the effectiveness of non-lethal deterrents through habituation. This study evaluated short-term behavioral responses and habituation patterns in a flock of magpies (Pica serica) that repeatedly foraged at the same site. A drone-only stimulus and a combined stimulus consisting of a drone carrying a taxidermized magpie with conspecific mobbing-call playback were applied sequentially six and five times, respectively, at two-day intervals. Each trial consisted of 10 min of stimulus exposure followed by 50 min of post-stimulus observation. Magpie numbers were recorded at 5-min intervals, and behaviors were classified as predator-related or predator non-related based on field observations. Audio recordings were also collected to interpret mobbing calls and behavioral context. Under the drone-only stimulus, predator-related behavior increased immediately after stimulus onset, but this response declined over repeated trials, and predator non-related behavior recovered even during stimulus exposure, suggesting rapid habituation. Under the combined stimulus, no magpies remained in the experimental area during stimulus exposure in any trial, and in early trials they did not return before the end of observation. However, in later trials, individuals showing non-predator-related behavior re-entered the area 20-25 min after stimulus removal, indicating that habituation was delayed but not fully suppressed. These results suggest that a species-specific combined stimulus can induce stronger short-term avoidance and delay habituation compared with drone-only stimulus, but additional strategies are required to maintain deterrent effectiveness during repeated applications.
