Introduction: Rapid environmental change driven by urbanization offers a unique insight into the adaptive potential of urban‐dwelling organisms. Urban‐driven phenotypic differentiation is increasingly often demonstrated, but the impact of urbanization (here modelled as the percentage of impervious surface (ISA) around each nestbox) on offspring developmental rates and subsequent survival remains poorly understood. Furthermore, the role of selection on urban‐driven phenotypic divergence was rarely investigated to date.Methods and Results: Data on nestling development and body mass were analysed in a gradient of urbanization set in Warsaw, Poland, in two passerine species: great tits (Parus major) and blue tits (Cyanistes caeruleus). Increasing levels of impervious surface area (ISA) delayed the age of fastest growth in blue tits. Nestling body mass was also negatively affected by increasing ISA 5 and 10 days after hatching in great tits, and 10 and 15 days in blue tits, respectively. High levels of ISA also increased nestling mortality 5 and 10 days after hatching in both species. An analysis of selection differentials performed for two levels of urbanization (low and high ISA) revealed a positive association between mass at day 2 and survival at fledging.Discussion: This study confirms the considerable negative impact of imperviousness—a proxy for urbanization level—on offspring development, body mass and survival, and highlights increased selection on avian mass at hatching in a high ISA environment.

Ticks are obligate haematophagous ectoparasites of vertebrates and frequently parasitize avian species that can carry them across continents during their long-distance migrations. Ticks may have detrimental effects on the health state of their avian hosts, which can be either directly caused by blood-draining or mediated by microbial pathogens transmitted during the blood meal. Indeed, ticks host complex microbial communities, including bacterial pathogens and symbionts. Midichloria bacteria (Rickettsiales) are widespread tick endosymbionts that can be transmitted to vertebrate hosts during the tick bite, inducing an antibody response. Their actual role as infectious/pathogenic agents is, however, unclear. We screened for Midichloria DNA African ticks and blood samples collected from trans-Saharan migratory songbirds at their arrival in Europe during spring migration. Tick infestation rate was 5.7%, with most ticks belonging to the Hyalomma marginatum species complex. Over 90% of Hyalomma ticks harboured DNA of Midichloria bacteria belonging to the monophylum associated with ticks. Midichloria DNA was detected in 43% of blood samples of avian hosts. Tick-infested adult birds were significantly more likely to test positive to the presence of Midichloria DNA than non-infested adults and second-year individuals, suggesting a long-term persistence of these bacteria within avian hosts. Tick parasitism was associated with a significantly delayed timing of spring migration of avian hosts but had no significant effects on body condition, whereas blood Midichloria DNA presence negatively affected fat deposits of tick-infested avian hosts. Our results show that ticks effectively transfer Midichloria bacteria to avian hosts, supporting the hypothesis that they are infectious to vertebrates. Bird infection likely enhances the horizontal spread of these bacteria across haematophagous ectoparasite populations. Moreover, we showed that Midichloria and tick parasitism have detrimental non-independent effects on avian host health during migration, highlighting the complexity of interactions involving ticks, their vertebrate hosts, and tick-borne bacteria.

Human‐provided nesting shelters such as nest‐boxes mitigate the shortage of natural breeding sites. Since artificial nests are not where animals evolved and optimised their reproductive performance, it remains inconclusive if these are adequate substitutes, ensuring equivalent fitness returns while breeding. In particular, most knowledge on the ecology of cavity‐nesting birds comes from nest‐box populations, but no study has directly compared fitness consequences of breeding inside nest‐boxes in relation to natural cavities in cities. We directly compare the reproductive performance, life‐history trait variation and fitness consequences for two small passerines, blue and great tits, breeding in nest‐boxes as opposed to natural cavities in an urban deciduous forest. We use a quasi‐experimental setting to comprehend the conservation potential of these artificial cavities and to support/question generalisations stemming from nest‐box studies. We show that the effects of cavity type vary between species: in blue tits, fitness proxies were negatively affected by nest‐boxes (lower fledging success and fledgling numbers, longer time spent in the nest and later fledging date relative to natural cavities), while in great tits, the fitness proxies were unaffected by cavity type. Importantly, we detected accelerated incubation in both species breeding in nest‐boxes. No differences in pre‐hatching traits (lay date, clutch size, hatching rates) between cavity types suggest that the fitness deterioration occurred because of post‐hatching effects. We highlight the ecological importance of old‐growth tree stands, providing natural cavities for city‐breeding animals and the need for quantifying alterations of reproductive ecology in other taxa using human‐provided nests. Owing to the detected cavity type‐dependent variation in reproductive performance, we support the criticism regarding the unconditional extrapolation of evolutionary and ecological interpretations of nest‐box studies to general populations.

Collecting and storing biological material from wild animals in a way that does not deteriorate DNA quality for subsequent analyses is instrumental for research in ecology and evolution. Our aims were to gather reports on the effectiveness of methods commonly used by researchers for the field collection and long‐term storage of blood samples and DNA extracts from wild birds. Personal experiences were collected with an online survey targeted specifically at researchers sampling wild birds. Many researchers experienced problems with blood sample storage but not with DNA extract storage. Storage issues generated problems with obtaining adequate DNA quality and sufficient DNA quantity for the targeted molecular analyses but were not related to season of blood sampling, access to equipment, transporting samples, temperature, and method of blood storage. Final DNA quality and quantity were also not affected by storage time before DNA extraction or the methods used to extract DNA. We discuss practical aspects of field collection and storage and provide some general recommendations, with a list of pros and cons of different preservation methods of avian blood samples and DNA extracts.

Protected areas are crucial for the conservation of West Africa’s increasingly imperiled wildlife, but are under unprecedented pressure associated with exponential human population growth in the region. Using birds as biodiversity indicators, we investigated the conservation status of Togo’s Fazao-Malfakassa National Park, which was managed by a private foundation from 1990 to 2015, and since 2015 has been managed by the state. Between 2022 and 2024, we conducted 90 days of bird surveys in the park and documented a total of 240 bird species. Our findings include 34 species new to the park, including the first record of Emin’s Shrike (Lanius gubernator) in Togo, the first sightings of the Great Blue Turaco (Corythaeola cristata) since 1990, and first observations of the Abyssinian Ground-Hornbill (Bucorvus abyssinicus) since 2019. Many such species survive in Togo only in Fazao-Malfakassa National Park, but its exceptional biodiversity has come under increasing assault from illegal activities, including poaching, logging, road construction, charcoal production, cattle grazing, and land clearance to establish agricultural plantations. We were unable to document 91 bird species previously reported for the park during our surveys, suggesting a possible ~31% decline in avian species richness in the park compared to historical records. Apparent extirpations of globally-threatened raptors such as the Critically Endangered White-backed Vulture (Gyps africanus) and Hooded Vulture (Necrosyrtes monachus), and declines of the Endangered Bateleur (Terathopius ecaudatus) and Martial Eagle (Polemaetus bellicosus) further indicate that current conservation strategies are failing to adequately protect wildlife in the park. Togo’s two other historical national parks have already been almost entirely destroyed by human activities, and unless urgent conservation action is taken, there is a high risk that Fazao-Malfakassa National Park will share the same fate. We urgently recommend improving support for law enforcement capacity and park staff, conducting community conservation outreach, and ongoing monitoring of wildlife in the park to assess its conservation success.

Most of our knowledge of secondary hole-nesting birds comes from populations breeding in human-provided nestboxes, yet these might differ from natural cavities in a number of parameters, including internal dimensions or microclimate, leading to differences in reproductive ecology. Here, we demonstrate differences in plumage coloration, an important visual signal of individual quality, in Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) nestlings raised in natural cavities and nestboxes. For this study, we collected feather samples over 2 breeding seasons and applied reflectance spectrophotometry to calculate color metrics. Carotenoid chroma was higher in nestbox-reared Blue Tits, whereas brightness was higher in nestbox-reared Great Tits (with a similar tendency for Blue Tits). The latter result might be explained by the better nutritional condition of Great Tit nestlings raised in nestboxes. Furthermore, we found no evidence for preference of adults expressing more elaborate plumage towards a specific cavity type in either species. Consequently, we assume that differences in nestling plumage reported here are driven by rearing conditions (nestboxes vs. natural cavities) and not by differences in plumage-based parental quality. Our study adds to the growing body of evidence confirming that anthropogenic environmental modifiers, such as nestboxes, might influence avian physiology and the resulting phenotype.