Mateusz Ledwon

• PhD
• Researcher at Institute of Systematics and Evolution of Animals, Polish Academy of Sciences

The highly pathogenic avian influenza virus (HPAIV) A(H5N1) has caused the most extensive and severe epizootic event affecting both poultry and wild birds globally. This study investigated the impact of HPAIV on the breeding population of the Black-headed Gull Chroicocephalus ridibundus, the most abundant gull species in Poland. During the 2023 out...

During spring and summer 2023, the highly pathogenic avian influenza (HPAI) H5N1 virus caused mass mortality among colony-breeding gulls and terns in Poland. Surveys were primarily focused within breeding colonies of Black-headed Gulls Chroicocephalus ridibundus, an ‘umbrella species’ whose breeding colonies serve as nesting sites for other scarce...

The fundamental trade‐off between current and future reproduction has long been considered to result in a tendency for species that can grow large to begin reproduction at a larger size. Due to the prolonged time required to reach maturity, estimates of tree maturation size remain very rare and we lack a global view on the generality and the shape...

The efficient conversion of tissues into reproductive success is a crucial aspect affecting the evolution of life histories. Masting, the interannually variable and synchronous seed production in perennial plants, is a strategy that can enhance reproductive efficiency by mitigating seed predation and pollen limitation. However, evaluating benefits...

An equal sex ratio at the population level is the usual, evolutionarily stable condition. However, at the individual level, it may be adaptive for parents to manipulate the sex of their offspring, especially in species with sexual size dimorphism (SSD) when the costs and benefits of producing sons and daughters can vary. In this study, we investiga...

Masting (synchronous and interannually variable seed production) is frequently called a reproductive strategy; yet it is unclear whether the reproductive behaviour of individuals has a heritable component. To address this, we used 22 years of annual fruit production data from 110 Sorbus aucuparia L. trees to examine the contributions of genetic fac...

Understanding the variation in fecundity, the reproductive capacity of individual trees, is crucial for predicting population dynamics and ecosystem functioning. However, estimating tree fecundity is challenging due to the large variation in seed production observed between trees and across years that necessitates logistically challenging long-term...

Vector-transmitted haemosporidians are among the most common parasites in birds, but our knowledge of the inter-specific patterns of infection rates and the parasite community composition is far from complete because of the unequal distribution of the screening effort across bird families and genera. To assess infection rates and the diversity of h...

Offspring desertion by a single parent, mainly the female, occurs in many charadriiform birds. According to the differential parental capacity hypothesis (DPCH), females are more likely to desert, since they may be in poorer body condition than males as a consequence of egg-laying costs. This study investigated the body condition of 122 male and 11...

Immunogenetic variation in natural vertebrate populations is expected to respond to spatial and temporal fluctuations in pathogen assemblages. While spatial heterogeneity in pathogen-driven selection enhances local immunogenetic adaptations and population divergence, different immune genes may yield contrasting responses to the environment. Here, w...

Vector-transmitted haemosporidians are among the most common parasites in birds, but our knowledge of the inter-specific patterns of infection rates and the parasite community composition is far from complete because of the unequal distribution of the screening effort across bird families and genera. To assess infection rates and the diversity of h...

In species with biparental care, one parent may relieve him-/herself of the costs of parental care by deserting and leaving the mate to care for the offspring. Offspring desertion by a single parent, usually the female, occurs in many bird species, especially in Charadriiformes. The reasons for desertion are still being debated, and compelling evid...

Aim Our understanding of the mechanisms that maintain forest diversity under changing climate can benefit from knowledge about traits that are closely linked to fitness. We tested whether the link between traits and seed number and seed size is consistent with two hypotheses, termed the leaf economics spectrum and the plant size syndrome, or whethe...

Understanding important factors for breeding Eared Grebes (Podiceps nigricollis) is essential for its conservation. We aimed to study the impact of some factors on nests and breeding success in this species in fishponds (S Poland). Number of Eared Grebe nests were counted on particular carp ponds. Pond size, vegetation cover, number of nests in col...

The animal dispersal hypothesis predicts that mast seeding can increase dispersal rate of seeds by dispersers and enhance reproductive success of plants. However, in contrast to pollination efficiency and predator satiation hypothesis, the animal dispersal hypothesis has received mixed support. Using 12‐year data on fruit production and seedling re...

Mewa białogłowa Larus cachinnans zaczęła gniazdować w Polsce na początku lat 80. XX w. Od 1989 gatunek ten gniazduje w kraju corocznie, ale jak dotąd nie przeprowadzono kompletnego cenzusu populacji lęgowej. By scharakteryzować trend, zebraliśmy dane dotyczące liczebności i rozmieszczenia lęgowych mew białogłowych do 2020 roku od obserwatorów z cał...

The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundat...

Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a dataset that collates reproductive time-series d...

Forest ecosystems contain many tree-related microhabitats (TreMs), which are used by various groups of organisms. Birds use TreMs for shelter, foraging and breeding. The abundance and variability of TreMs is related to tree stand composition and age. Over the last few centuries there has been a drastic decline in the structural and biological diver...

Masting is a widespread reproductive strategy in plants that helps to reduce seed predation and increase pollination. However, masting can involve costs, notably negative density‐dependent (NDD) seedling survival caused by concentrating reproduction in intermittent events. Masting benefits have received widespread attention, but the costs are under...

Patterns of extra pair paternity (EPP) and intraspecific brood parasitism (IBP) were studied in a Whiskered Tern Chlidonias hybrida population characterized by female brood desertion, a high level of extra pair courtship feedings (10%) and a low level of extra pair copulation (EPC; 0.6%). In this study, we used a set of microsatellite loci to analy...

To understand the proximate mechanisms regulating brood desertion, we studied hormonal and behavioural stress responses during the chick-rearing period in adult Whiskered Terns (Chlidonias hybrida), a socially monogamous, semi-precocial species with prolonged post-fledging parental care. In contrast to males, almost all females of this species dese...

Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current esti...

The growth of a nestling during the first few weeks after hatching is crucial for its further life and is sensitive to the conditions experienced during this period. Among species exhibiting Sexual Size Dimorphism (SSD), one of the most important factors influencing growth parameters is the sex of the hatchlings. In this study, we tested whether se...

Acinetobacter baumannii is a worldwide occurring nosocomial pathogen, the natural habitats of which remain to be defined. Recently, white stork nestlings have been described as a recurring source of A. baumannii. Here, we challenged the hypothesis of a general preference of A. baumannii for avian hosts. Taking advantage of campaigns to ring free-li...

There is increasing evidence that melanin-based plumage ornaments play a role in the sexual selection of birds, although there seems to be little consensus on the mechanisms underlying the signalling function of melanin-based plumage. The aim of this study was to assess the potential of a melanin-based plumage ornament (brown hood) to reflect compo...

In species where the offspring are naturally deserted by one parent, the experimental stressing of breeding individuals can provide valuable information on the mechanisms underlying desertions and thus the evolution of parental roles. During a study conducted in southern Poland in 2016 and 2017, we investigated factors influencing desertion during...

The Caspian Gull Larus cachinnans is a monogamous species in which both partners make a large investment in parental care. An adult female and her mate in a breeding colony in the Upper Vistula River Valley, southern Poland, were equipped with GPS/GSM-transmitters (provided by ECOTONE). The solar-charged 19g loggers recorded the birds’ geographical...

Trees are commonly thought to increase their seed production before death. We tested this terminal investment hypothesis using long-term data on rowan trees ( Sorbus aucuparia ) and found no support. Rather, seed production declined significantly before death, which points to the potential detrimental effects of reproductive senescence on regenerat...

Synchronized and variable reproduction by perennial plants, called mast seeding, is a major reproductive strategy of trees. The need to accumulate sufficient resources after depletion following fruiting (resource budget), the efficiency of mass flowering for outcross pollination (pollen coupling), or the external factors preventing reproduction (en...

The Caspian Gull Larus cachinnans is a species which colonizes new areas in Central Europe. We investigates the migration strategy and movements of this species. One adult female was tagged with GPS/GSM transmitters (provided Ecotone) in April 2016 in a breeding colony in southern Poland. During the breeding season, this bird usually foraged on rub...

Males of many bird species feed their mates during the pre‐incubation period. The food provisioned by males during these courtship feedings (CFs) represents the key source of energy for the female during egg formation. Non‐pair males may trade food for Extra Pair Copulations (EPC) with females during Extra Pair Courtship Feeding (EPCF), while femal...

The level of reproductive investment and density‐ and distance‐dependent ( DDD ) processes are major determinants of plant reproductive output. The reproductive investment of a plant population varies temporally, but whether and how DDD processes are affected by population‐level reproductive investment is a puzzle. We used a spatially explicit appr...

Contrasting the general trend of declining Afro-Palearctic migratory bird populations, the Whiskered Tern (Chlidonias hybrida hybrida) has recently exhibited spectacular demographic expansion and range shifts across its patchy European breeding distribution. To explore population connectivity of this species, individuals sampled from four sites in...

Understanding foraging strategies remains a central question in behavioural ecology, but studies investigating how foraging of sexes is affected by other individual characteristics, like body size, are still scarce. We investigated how foraging behaviour during chick rearing varies in males and females with brood size, offspring age and individual...

In species with biparental care, a conflict of interest can arise if one mate tries to maximize its own reproductive success at the expense of the other’s. One of the mates can desert the brood to accrue a number of benefits to enhance its own fitness, leaving parental care to the remaining parent. This study is the first to describe the desertion...

We studied sex-specific differences in prey returned to nests and eaten by parents in Whiskered Terns Chlidonias hybrida. The species is size-dimorphic, with females being smaller than males. The sex of the birds was determined by molecular analysis. Prey consumed and carried to chicks was recorded at short (<300 m) and long distances (>300 m) from...

Capsule In the Whiskered Tern Chlidonias hybrida, hatching success was similar at nests where both parents were caught during the same trapping session and nests where parents were caught on different days. Trapping both mates during the same session may represent an efficient approach to reduce fieldwork effort, but it should be preceded by a pilo...

Capsule: Evidence from two tern species does not support the theory that species in expansion should bias their brood sex ratios towards the more dispersing sex. Aims: Sex ratio theory predicts that when a species is in expansion, the sex ratio should be biased towards the more dispersing sex. We compared the sex ratio of nestlings in two closely r...

A method for trapping both parents of Whiskered Terns (Chlidonias hybrida), a semi-precocial species, using enclosures that allow access to the chicks until they fledge is described. The approach combines the gradual installation of enclosures with their subsequent, temporary conversion into traps used to capture adult birds. The success rate for t...

Sexual size dimorphism is common in many bird species. It can lead to sex-specific differences in foraging ability. The Whiskered Tern (Chlidonias hybrida) exhibits sexual size dimorphism. Sex-specific differences in the foraging behaviour of Whiskered Terns were investigated in carp ponds during the breeding season. Foraging behaviour was differen...

The migratory strategy of herons is poorly understood: only that of Purple Heron has been well studied. The migratory movements of three Night Herons from the Upper Vistula Valley (Poland) were studied using a GPS/GSM-tracking system in 2012. The results docu-ment a previously unknown autumn migration strategy of Night Herons with long stopovers en...

The Whiskered Tern population in Poland has rapidly increased from 40 breeding pairs in 1990 to over 1,600 in 2007, with strongest local population in the Upper Vistula River Valley. Owing to rather low pre-breeding and adult apparent survival rates estimated for this population (0.54 and 0.80, respectively) and a delay in accession to reproduction...

Sexual size dimorphism is common in many bird species. It can lead to sex-specific differ-ences in foraging ability. The Whiskered Tern Chlidonias hybrida exhibits sexual size di-morphism. Sex-specific differences in the foraging behaviour of Whiskered Terns were investigated in carp ponds during the breeding season. Foraging behaviour was differen...

We present the first-ever survival estimates of the Whiskered Tern Chlidonias hybrida, based on the analysis of capture–recapture data (403 adults and 1,484 chicks ringed) collected between 1993 and 2011 in an increasing breeding population in southern Poland. Data were modelled using multistate models with an unobservable state, accounting for the...

The predator satiation hypothesis states that synchronous periodic production of seeds is an adaptive strategy evolved to reduce the pressure of seed predators. The seed production pattern is crucial to the predator satiation hypothesis, but there are few studies documenting the success of individuals that are in synchrony and out of synchrony with...

Masting is usually considered as a population phenomenon but it results from individuals’ reproductive patterns. Studies of individual patterns of seed production and their synchrony are essential to an understanding of the mechanisms of masting. The aim of this study was to find the relationship between population and individual levels of masting....

On 16 and 23.06.2012 one nest of Little Egret Egretta garzetta was found and have been inspected in the colony of Night Herons located at fish ponds in Ochaby (Skoczów, south Poland). Brood was successful and 3 fledglings left nest. First-ever record of breeding Little Egret in Poland from 2003 took place also in colony of Night Herons at a distanc...

I examined sexual size dimorphism (SSD) and assortative mating and estimated a discriminant function for predicting sex in the Whiskered Tern Chlidonias hybrida, a medium-sized marsh tern. I measured and molecularly sexed 241 breeding adults captured in southern Poland from 2005 to 2010. Males were significantly larger than females in all six measu...

In 2005–2006 the distribution and abundance of the breeding populations of the Dipper Cinclus cinclus and Grey Wagtail Motacilla cinerea were studied in the western part of the Beskidy Zachodnie Mountains and Pogórze Zachodniobeskidzkie foothills. Jointly, 630 km of streams were surveyed. The Dipper population was estimated at 150–200 pairs, wherea...

Non-random seed shadows are commonly seen in plant species whose seeds are dispersed by animals, in particular by birds. The behaviour of birds can influence the spatial pattern of seed dispersal and, consequently, the entire regeneration process of fleshy-fruited trees. This study examined regeneration patterns in a fleshy-fruited tree species, ro...