Open research questions in Avian ecology and behavior
100 unresolved questions extracted from the limitations and future-work sections of 1,239 Avian ecology and behavior papers in our library. Each links back to the study that raised it.
What the literature leaves open
Abstract Background Individual variation in animal movement and habitat selection is increasingly recognised as a structurally important component of population ecology, yet the magnitude and temporal consistency of foraging movement specialisation remain poorly characterised in inland-breeding waterbirds.
Consistent individual differences in foraging movement tactics drive habitat partitioning in an inland-breeding Great Cormorant population · 2026 · DOIFuture research should investigate the seasonal dynamics of these bird communities, assess the functional consequences of the observed homogenization, and test the effectiveness of targeted landscape interventions (such as enhancing within- urban structural heterogeneity and promoting agricultural connectivity) designed to mitigate the dominance of urban generalists and support a more diverse and resilient avian assemblage.
Abundance and occurrence responses of bird communities to arid mixed urban-agricultural systems · 2026 · DOIAbstract Intraspecific trait variability (ITV) is a fundamental feature of biological populations and the raw material upon which natural selection acts, yet its drivers remain poorly understood.
Intraspecific variability in feather moult extent declines under both low and high constraints · 2026 · DOIABSTRACT Seasonal migration strategies can vary with life history demands and environmental context, yet such contrasts remain poorly documented for many shorebirds along the East Asian–Australasian Flyway (EAAF).
Seasonal Differences in Migration Routes and Stopover Use of Greater Sand Plovers Between Mongolia and the Beibu Gulf Revealed by GPS Tracking · 2026 · DOIThe limited data from five falcons (2 juveniles and 1 adult in 2021, 2 adults in 2022) suggest that adults and juveniles may behave differently on their southward migrations.
Migration stopover behaviour of Sooty Falcons <i>(Falco concolor)</i> during their southward journey · 2026 · DOIAlthough the ASMFC has indicated that the stock along the Atlantic Coast has not been overfished (SEDAR, 2020), the status and trends of adult menhaden within the Chesapeake Bay have not been evaluated.
These findings indicate that tropical cavity-nesting frugivores exhibit phenological plasticity coupled with demographic stability, though the mechanisms underlying this apparent buffering remain incompletely understood, and body size-dependent differences in thermal exposure suggest heterogeneous vulnerabilities to future warming scenarios.
Phenological Plasticity without Directional Change: Tropical Hornbills Track Temperature but Maintain Reproductive Stability · 2026 · DOI– Santosh Bhattarai, Bishal Prasad Neupane, Bivek Gautam, Prabin Shrestha, Ashley R. Olson, Fiona Hogan & Wendy Wright, Pp.
The study site captures migratory and resident passerines, but the excerpt lacks explicit data on winter bird community composition or wintering habitat requirements. Since Lehikoinen et al. (2021) document that wintering bird communities track climate change faster than breeding communities, integrating winter capture data or habitat use at the study site would reveal whether population declines originate from breeding grounds, wintering grounds, or migration corridors.
The paper documents population trends for 25 passerines in an anthropogenic habitat but does not explicitly compare breeding-season capture dynamics versus stopover phenology (arrival and departure timing) at the ringing station. Franzoi et al. (2021) and Lehikoinen et al. (2021) show migratory birds' phenology is decoupling from climate change; analyzing whether captures reflect true population declines or shifting migration windows would clarify if species are simply bypassing the study site due to phenological mismatch.
The study relies on capture data from bird ringing but does not distinguish between changes in breeding productivity versus adult survival rates as drivers of annual population variation in the 25 passerine species. Nousiainen et al. (2026) demonstrates that adult survival drives population change more strongly than productivity in European songbirds; applying this survival-productivity decomposition framework to this dataset would identify which demographic pathway explains each species' trend.
While the paper references agricultural intensification and forest management as drivers of passerine population changes (citing Reif et al. 2022, Donald et al. 2006), it does not quantitatively assess the specific mechanistic linkages between documented land-use changes at the study site and individual species' annual capture fluctuations. Direct measurement of habitat variables (crop types, pesticide use, vegetation structure) paired with capture data would clarify which habitat modifications most strongly influence each species' stopover ecology.
The study captures passerine population trends at a single anthropogenic habitat site in Hungary (Kevermes), but lacks comparative data from multiple agricultural landscape types across different regions to determine whether observed population changes are site-specific or reflect broader Central European patterns. Multi-site ringing stations with standardized protocols across varied habitat heterogeneity levels would enable regional generalization of the 25 passerine species' trend dynamics.
This study attempts to provide recent and unpublished data on the wintering and behavior of the black-headed gull, which remains poorly documented in North Africa and particularly in Algeria, and highlights the patterns of wetland use by these species, which could help to evaluate the importance of certain areas and develop management plans specific to coastal habitats and their avifaunal diversity.
Population dynamics and wintering behavior of the black–headed gull <i>Chroicocephalus ridibundus</i> at El Mellah lagoon (Northeastern Algeria) · 2023 · DOIMost studies on the EIE food composition covering different parts of the species distribution range analyse the breeding season, while data about the winter diet are scarce.
Diet of Eastern Imperial Eagle (Aquila heliaca) in Bulgaria: composition, distribution and variation · 2022 · DOIWe found that shorebirds at four of five sites were limited to artificial supratidal habitats at high tide for ~11-25 days per month because natural intertidal flats were completely covered by seawater.
To compare nest and non‐nest‐tree characteristics, the following data were collected from the literature: diameter at breast height ( DBH ) and its standard deviation ( SD ), sample size of trees with and without active nest, amount of nest and available trees described as dead or with a broken crown, and amount of nest and available trees that were lacking these characteristics.
Decaying trees improve nesting opportunities for cavity‐nesting birds in temperate and boreal forests: A meta‐analysis and implications for retention forestry · 2018 · DOIThere is very limited information on migration from bird ringing, only 8 recoveries between 1928–1963 indicate, that the Hungarian population is migrating on a south-southeast direction in autumn, wintering in the eastern parts of the Sahel, possibly in Chad and Sudan and migrates back in spring following a loop migration pattern further to the east.
The cat predation estimate of 69% mortality from un-owned cats (farm/barn cats, strays, feral colonies) lacks demographic breakdown by cat population subtype. Research should separately quantify predation rates from each un-owned cat category and test whether specific management interventions (colony management, barn cat containment) differentially reduce bird mortality across these distinct cat populations.
The snow bunting research applied geolocators for the first time on arctic-breeding passerines, but the comparative performance of geolocators versus mark-recapture (banding) data for detecting migratory connectivity in small-bodied songbirds has not been systematically evaluated. A validation study comparing accuracy, detection rates, and data quality between these technologies across multiple arctic passerine species would strengthen future migration tracking protocols.
The snow bunting migration study identified an east-west population divide at Hudson Bay using geolocators, stable-isotope analysis, and banding data, but wintering population connectivity within western North America requires additional investigation. Specifically, fine-scale winter movement patterns and site fidelity across multiple wintering locations need to be tracked using geolocators on larger sample sizes from western breeding populations.
The cat predation study estimated 2.4 billion annual bird mortalities but was based entirely on a meta-analysis of 90 previous studies without new empirical data collection. Direct field surveys quantifying predation rates across different habitat types (urban, suburban, rural) and cat management conditions are needed to validate these aggregate estimates and identify regional variation.
The Savannah sparrow song study tracked cultural evolution over 30 years using sonograms, but the mechanism driving female preference for shorter trills remains unexamined. Future research should experimentally manipulate trill length and duration in playback experiments to directly test whether female sparrows exhibit measurable reproductive preference differences based on these specific acoustic parameters.
Abstract Despite the key role of raptors (including birds of prey Falconiformes and owls Strigiformes) in ecosystems and their sensitivity to environmental change, a well coordinated, Europe-wide monitoring of raptors is lacking.
An overview of current monitoring schemes for raptor populations in 28 European countries, as reported by EURAPMON National Coordinators at the workshop in Murcia (Spain) in 2012, showed existing monitoring schemes to be limited to a restricted number of species (mostly diurnal and rare raptor species).
Most-cited papers in Avian ecology and behavior
- Moult terminology: envisioning an evolutionary approach · Journal of Avian Biology · 2024 · 295 citations
- Are Parrots CRAVED? An Analysis of Parrot Poaching in Mexico · Journal of Research in Crime and Delinquency · 2011 · 179 citations
- Population Abundance and Ecosystem Service Provision: The Case of Birds · BioScience · 2018 · 129 citations
- Species richness is positively related to mental health – A study for Germany · Landscape and Urban Planning · 2021 · 126 citations
- Multiple habitat use by declining migratory birds necessitates joined‐up conservation · Ecology and Evolution · 2019 · 81 citations
- Status and trends of tundra birds across the circumpolar Arctic · AMBIO · 2020 · 76 citations
- Phenological mismatch in Arctic‐breeding shorebirds: Impact of snowmelt and unpredictable weather conditions on food availability and chick growth · Ecology and Evolution · 2019 · 71 citations
- Combined effects of heat waves and droughts on avian communities across the conterminous United States · Ecosphere · 2010 · 71 citations
- Multiple Residence and Cyclical Migration: A Life Course Perspective* · The Professional Geographer · 1995 · 64 citations
- Decaying trees improve nesting opportunities for cavity‐nesting birds in temperate and boreal forests: A meta‐analysis and implications for retention forestry · Ecology and Evolution · 2018 · 62 citations
Most recent work
- Breeding distribution of the Vulnerable Sooty Falcon <i>(Falco concolor)</i> in northwestern Saudi Arabia, the NEOM region · Ornis Hungarica · 2026
- Sooty Falcon <i>(Falco concolor)</i> in the northern Saudi Arabian Red Sea: population assessment and conservation · Ornis Hungarica · 2026
- Nesting of Sooty Falcon <i>Falco concolor</i> (Temminck, 1825) in Libya 2020–2024 · Ornis Hungarica · 2026
- Global conservation status and population trends of the Sooty Falcon <i>(Falco concolor)</i> · Ornis Hungarica · 2026
- Nest selection and usage of nest boxes by the Sooty Falcon <i>(Falco concolor)</i> in the Al Wajh Bank (Saudi Arabia) · Ornis Hungarica · 2026
- Predicting climate change impacts on a trans-equatorial migrant breeding falcon of the Saharo-Sindian region · Ornis Hungarica · 2026
- First confirmation of inland nesting for the Sooty Falcon <i>(Falco concolor)</i> in the AlUla region, Saudi Arabia: A new population revealed · Ornis Hungarica · 2026
- Observations on the Sooty Falcon <i>(Falco concolor)</i> : nesting behaviour and distribution in Egypt · Ornis Hungarica · 2026
- Evidence of emperor penguins’ sensitivity to sea ice fluctuations · Proceedings of the Royal Society B: Biological Sciences · 2026
- Long-term changes over 40 years in the avifauna of an urban reserve: Birrarung Park, Melbourne, Australia · Pacific Conservation Biology · 2026
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