Mark E Hauber

City University of New York - Hunter College | Hunter CUNY · Department of Psychology

Eggshell recognition in parental birds is vital for nest management, defense against brood parasitism, optimal embryonic development, and minimizing disease and predation risks. This process relies on acceptance thresholds balancing the risk of rejecting own eggs against the benefit of excluding foreign ones, following signal detection theory. We i...

As the avian embryo grows and develops within the egg, its metabolic rate gradually increases. Obligate avian brood-parasitic birds lay their eggs in the nests of other species to avoid the costs of parental care, and all but one of these brood-parasitic species are altricial at hatching. Yet the chicks of some altricial brood-parasitic species per...

Introduced species can represent quasi-experimental, anthropogenic case studies of both ecological and evolutionary principles. When these species are firmly established, competitive interactions between native and introduced species, including foraging, spacing, and breeding competition, may be among the ecological costs incurred from such species...

Redondo and Amat (Nest switching vs. nest integration: a comment on Fernandez-Duque et al. Evolutionary Ecology, 2024) commented on our recent report of freely moving altricial fledglings incorporating themselves into the brood of a conspecific nest with offspring too young to fly. The authors bring up both related examples of this behavior in othe...

Sex-limited polymorphism has evolved in many species including our own. Yet, we lack a detailed understanding of the underlying genetic variation and evolutionary processes at work. The brood parasitic common cuckoo ( Cuculus canorus ) is a prime example of female-limited color polymorphism, where adult males are monochromatic gray and females exhi...

Alarm signals have evolved to communicate imminent threats to conspecifics but animals may also perceive other species' alarm displays to obtain adaptive information. In birds, mixed‐species foraging flocks are often structured around a focal sentinel species, which produces reliable alarm calls that inform eavesdropping non‐sentinel heterospecific...

Nagy, J., Hauber, M. E., Löki, V. & Mainwaring, M. C. (2024) Plumage and eggshell colouration covary with the level of sex-specific parental contributions to nest building in birds. The Science of Nature, 111(2): 12. // Data available at Figshare https://doi.org/10.6084/m9.figshare.25268398.v1

Interspecific variation in sex-specific contributions to prenatal parental care, including avian nest building, is becoming increasingly better understood as we amass more information on more species. We examined whether sex-specific nest building contributions covary with the colouration of parents and their eggs in 521 species of Western Palearct...

Evolution, driven by genetic factors and complemented by phenotypic plasticity, is crucial for a species' longevity amidst environmental changes. Behavioral adaptability, particularly in parental care, plays a key role in evolutionary outcomes, posing challenges and opportunities for adaptation in the rapidly changing Anthropocene era, highlighting...

Uncovering the genomic bases of phenotypic adaptation is a major goal in biology, but this has been hard to achieve for complex behavioral traits. Here, we leverage the repeated, independent evolution of obligate cavity-nesting in birds to test the hypothesis that pressure to compete for a limited breeding resource has facilitated convergent evolut...

The role of species interactions, as well as genetic and environmental factors, all likely contribute to the composition and structure of the gut microbiome; however, disentangling these independent factors under field conditions represents a challenge for a functional understanding of gut microbial ecology. Avian brood parasites provide unique opp...

In animal communication, functionally referential alarm calls elicit the same behavioral responses as their referents, despite their typically distinct bioacoustic traits. Yet the auditory forebrain in at least one songbird species, the black-capped chickadee Poecile atricapillus, responds similarly to threat calls and their referent predatory owl...

Brood (social) parasites and their hosts exhibit a wide range of adaptations and counter-adaptations as part of their ongoing coevolutionary arms races. Obligate avian brood parasites are expected to use potential host species with more easily accessible nests, while potential hosts are expected to evade parasitism by building more concealed nests...

Hauber Mark E., Nagy Jenő, Sheard Catherine, Antonson Nicholas D., Street Sally E., Healy Susan D., Lala Kevin N. and Mainwaring Mark C. (2024) Nest architecture influences host use by avian brood parasites and is shaped by coevolutionary dynamics Proc. R. Soc. B 291: 20231734 // Supplementary figures and tables, additional analyses // Available at...

Groups of animals inhabit vastly different sensory worlds, or umwelten, which shape fundamental aspects of their behaviour. Yet the sensory ecology of species is rarely incorporated into the emerging field of collective behaviour, which studies the movements, population-level behaviours, and emergent properties of animal groups. Here, we review the...

Species interactions link animal behaviour to community structure and macroecological patterns of biodiversity. One common type of trophic species interaction is disturbance foraging—the act of obtaining food at a disturbance created by another organism. Disturbance foraging is widespread across the animal kingdom, especially among birds, yet previ...

Despite broad interest and recent experimentation, there is no single ecological model accounting for the adaptive significance of the diversity of avian eggshell colouration. The often blue-green eggs of Turdus thrushes are a charismatic example of this, having long captured cultural and scientific attention. Although the biology and evolutionary...

Behavioral imprinting is a learning phenomenon by which animals acquire preferences for stimuli through perceptual exposure during critical periods, without substantial external reinforcement. Since being acknowledged in 1516 by Sir Thomas More in artificially incubated domestic chickens, imprinting has been reported in diverse species, across vari...

Competition over resources often leads to intra‐ and interspecific interactions, which can be detrimental to the individuals involved. Thus, natural selection should favor communication systems that reliably convey information regarding the relative competitive abilities of an individual, reducing the need for physically damaging confrontation. Bod...

Vocal production learning (the capacity to learn to produce vocalizations) is a multidimensional trait that involves different learning mechanisms during different temporal and socioecological contexts. Key outstanding questions are whether vocal production learning begins during the embryonic stage and whether mothers play an active role in this t...

Alarm signals have evolved to communicate pertinent threats to conspecifics, but heterospecifics may also use alarm calls to obtain social information. In birds, mixed-species flocks are often structured around focal sentinel species, which produce reliable alarm calls that inform eavesdropping heterospecifics about predation risk. Prior research h...

Mimicry is a widespread phenomenon whereby predatory or parasitic individuals can access unsuspecting prey or hosts for the former’s benefit. For example, brood parasitic common cuckoos (Cuculus canorus) evolved several adaptations to trick hosts, including host-mimetic eggs, a barred chest plumage resembling the predatory Eurasian sparrowhawk (Acc...

Egg rejection is an effective and widespread antiparasitic defense to eliminate foreign eggs from the nests of hosts of brood parasitic birds. Several lines of observational and critical experimental evidence support a role for learning by hosts in the recognition of parasitic versus own eggs; specifically, individual hosts that have had prior or c...

Animals across diverse lineages use referential calls to warn of and respond to specific threats, and the ability to understand these calls may be dependent on experience with the threat being referenced. Yellow warblers (Setophaga petechia) produce referential ‘seet’ calls towards brood parasitic brown-headed cowbirds (Molothrus ater), which threa...

Parental investment in offspring provides fitness benefits for progeny but incurs costs for parents. However, in birds there is a paucity of information on the foraging behaviors of altricial young once they leave the nest. Here we report a novel form of food acquisition in an altricial bird that is driven by a fledgling itself rather than its pare...

Perceived predation and brood parasitism risks strongly influence nesting habitat selection in several bird species. Here, we report on a playback experiment evaluating whether perceived predation or brood parasitism risk can reduce Red-winged Blackbird (Agelaius phoeniceus) abundances in agricultural nesting habitat. We broadcast Cooper’s Hawk voc...

Nests, including the enormous structures housing colonies of eusocial insects and the elaborately built nests of some fishes, have long fascinated scientists, yet our understanding of the evolutionary ecology of nests has lagged behind our understanding of subsequent reproductive stages. There has, however, been a burgeoning amount of interest in n...

The evolution of nest site use and nest architecture in the non-avian ancestors of birds remains poorly understood because nest structures do not preserve well as fossils. Nevertheless, the evidence suggests that the earliest dinosaurs probably buried eggs below ground and covered them with soil so that heat from the substrate fuelled embryo develo...

Personality traits can remain consistent throughout adult life, but it is less clear when these behavioural differences first arise and whether they are maintained across ontogenetic stages. We measured personality across three life stages (nestling, fledgling, and adult) in a wild population of superb fairy-wrens ( Malurus cyaneus ). We assessed (...

Hosts of obligate avian brood parasites often evolve defense mechanisms to avoid rearing unrelated young. One common defense is egg rejection for which hosts often rely on eggshell color. Most research has assumed that hosts respond to perceived color differences between their own eggs and parasite eggs regardless of the particular color; however,...

American robins ( Turdus migratorius ) are among few hosts of parasitic brown-headed cowbirds ( Molothrus ater ) that frequently eject foreign eggs from their nests. However, we know little about some characteristics of the robins’ egg ejection process including its distance and direction. We used a novel technique (i.e., radio transmitters inserte...

Eggs are critically important for avian reproduction as all birds are oviparous. Accordingly, the recognition and care of own eggs represent the cornerstones of avian breeding, whereas the elimination of foreign objects, including brood-parasitic eggs and non-egg items from the nest are known to also increase fitness by refocusing incubation effort...

Birdsong is a longstanding model system for studying evolution and biodiversity. Here, we collected and analyzed high quality song recordings from seven species in the family Estrildidae . We measured the acoustic features of syllables and then used dimensionality reduction and machine learning classifiers to identify features that accurately assig...

Predation or brood parasitism risks can change the behaviors and reproductive decisions in many parental animals. For oviparous species, mothers can mitigate their reproductive success in at least three ways: (1) by avoiding nest sites with high predation or parasitism risks, (2) through hormonal maternal effects that developmentally prime offsprin...

In oviparous animals, egg morphology is considered an aspect of the extended phenotype of the laying mother and, thus, can be directly assessed for consistency both within and between individual females. Despite a recently renewed interest in the evolution and mechanics of avian eggshell morphology, we still lack a large-scale, comparative understa...

Hybridization is a known source of morphological, functional and communicative signal novelty in many organisms. Although diverse mechanisms of established novel ornamentation have been identified in natural populations, we lack an understanding of hybridization effects across levels of biological scales and upon phylogenies. Hummingbirds display d...

Birdsong is a longstanding model system for studying evolution, and has recently emerged as a measure of biodiversity loss due to deforestation and climate change. Here, we collected and analyzed high quality song recordings from seven species in the family Estrildidae . We measured the acoustic features of syllables and then used dimensionality re...

In functionally referential communication systems, the signaler's message intended for a conspecific receiver may be intercepted and used by a heterospecific eavesdropper for its own benefit. For example, yellow warblers (Setophaga petechia) produce seet calls to warn conspecifics of nearby brood parasitic brown‐headed cowbirds (Molothrus ater), an...

In many bird species loud broadcast calls serve as aggressive signals with a large effective radius, whereas soft calls may indicate aggression at a closer distance, and are often directed at a nearby conspecific individual. Male common cuckoos (Cuculus canorus) are famous for their simple cu-coo calls, which are long-range broadcast calls, uttered...

The avian palaeognath phylogeny has been recently revised significantly due to the advancement of genome-wide comparative analyses and provides the opportunity to trace the evolution of the microstructure and crystallography of modern dinosaur eggshells. Here, eggshells of all major clades of Palaeognathae (including extinct taxa) and selected eggs...

One of the most effective defenses of avian hosts against obligate brood parasites is the ejection of parasitic eggs from the nests. Despite the clear fitness benefits of this behavior, individuals within so‐called “egg‐rejecter” host species still show substantial variation in their propensity to eliminate foreign eggs from the nest. We argue that...

Nest‐sharer avian brood parasites do not evict or otherwise kill host chicks, but instead inflict a range of negative effects on their nestmates that are mediated by interactions between the parasite and host life history traits. Although many of the negative fitness effects of avian brood parasitism are well documented across diverse host species,...

Most host species of the obligate brood parasitic Brown-headed Cowbird (Molothrus ater) accept foreign eggs and offspring despite the associated reproductive costs. One theoretical explanation for this host tolerance is the potential for mafia-like behavior by the brood parasite, which involves the retaliatory destruction of a host’s eggs and/or ne...

Avian obligate brood parasites rely on other species to raise their offspring. In turn, many brood parasite hosts have evolved defensive behaviors to reduce the costs of brood parasitism, yet the proximate bases underlying these defenses remain poorly understood. Recent studies regarding the potential endocrine mechanisms of foreign-egg rejection h...

The Prothonotary Warbler ( Protonotaria citrea ) is a nearctic-neotropical migratory songbird that breeds in forested swamps and riparian areas in the eastern-central United States and southern Ontario. It is the sole eastern North American wood-warbler that nests in cavities, the only species in the genus Protonotaria , and is one of the few hole-...

Ecological conditions limiting the time to find a compatible mate or increasing the difficulty in doing so likely promote the evolution of traits used for species and mate recognition. In addition to interspecific character displacement signalling species identity, intraspecific traits that signal an individual's sex and breeding status reduce the...

Generalist brood parasites that share nests with host nestlings can optimize resource acquisition from host parents by balancing the benefits that host nest-mates provide, including attracting increased provisions to the nest, against the costs of competing with the same host young over foster parental resources. However, it is unclear how parasiti...

Acoustic communication of animals often contains two types of vocalizations: loud sounds for long-range, and soft sounds for short-range signalling. Brood parasitic common cuckoos (Cuculus canorus) are suitable study objects for research of acoustic signalling as they have a simple acoustic repertoire, of which the loud territorial advertisement ca...

The relationships between avian brood parasites and their hosts are widely recognised as model systems for studying coevolution. However, while most brood parasites are known to parasitise multiple species of host and hosts are often subject to parasitism by multiple brood parasite species, the examination of multispecies interactions remains rare....

One of the most effective defenses of avian hosts against obligate brood parasites is the ejection of parasitic eggs from the nests. Despite the clear fitness benefits of this behavior, individuals within so-called “egg rejecter” host species still show substantial variation in their propensity to eliminate foreign eggs from the nest. We argue that...

Avian brood parasitism is reproductively costly for hosts and selects for cognitive features enabling anti-parasitic resistance at multiple stages of the host's breeding cycle. The true thrushes (genus Turdus) represent a nearly worldwide clade of potential hosts of brood parasitism by Cuculus cuckoos in Eurasia and Africa and Molothrus cowbirds in...

Social media platforms, such as Twitter, provide the opportunity for academics to network and to disseminate research to colleagues and the general public. More recently, Twitter in particular has become a platform for hosting academic conferences in addition to or as an alternative to either traditional in-person academic conferences or virtual co...

Transitions between life history stages are fitness-limiting events that depend on environmental and individual characteristics. For altricial birds, fledging from the nest is a critical shift in development with direct impacts on survival, yet it remains one of the most understudied components of avian ontogeny. Even less is known about how brood...

Personality, or repeatable variation in behavior, may impact an animal's survival or reproduction. Parental aggression is one such personality trait with potentially direct implications for fitness, as it can improve offspring survival during vulnerable early life stages. We took advantage of a long‐term nest box and fledgling survival monitoring p...

The antagonistic arms races between obligate brood parasites and their hosts provide critical insights into coevolutionary processes and constraints on the evolution of life history strategies. In avian brood parasites—a model system for examining host–parasite dynamics—research has primarily focused on the egg and nestling stage, while far less is...

Communication between parents and dependent offspring is critical not only during provisioning, but also in antipredator contexts. In altricial birds, a top cause of reproductive failure is nest predation, and alarm calls both by parents and chicks can serve to alert others and increase the likelihood of offspring escaping predation. Understanding...

To curb fitness costs associated with obligate avian brood parasitism, some hosts have evolved to reject foreign eggs in the nest. American robins (Turdus migratorius) are among the few hosts of the brown-headed cowbird (Molothrus ater) that mostly remove parasitic eggs from their nests. With the parasite’s eggs looking nothing like their own, Amer...

Despite posing a serious threat to global biodiversity, national and international management efforts have not been able to limit the spread of most invasive species. In highly dispersive species, local invasions may be followed by regional range expansion that crosses international borders. In such cases, independent management efforts of the inva...

Obligate brood parasitic birds lay their eggs in the nests of other species, reducing the host’s own reproductive output. To circumvent these fitness costs, many—but not all—host species have evolved the ability to recognize and reject brood parasitic eggs. What factors constrain egg rejection, and why do host species vary in their likelihood of re...

Hauber, M.E., Riehl, C. & Nagy, J. (2022) Clutch size and the rejection of parasitic eggs: a comparative test of the maternal investment hypothesis. Evolutionary Ecology // Content: AIC tables and model detail // Raw data available at Figshare https://figshare.com/s/e2fa76fa80382edb5d67

Brain plasticity is widespread in nature, as it enables adaptive responses to sensory demands associated with novel stimuli, environmental changes and social conditions. Social Hymenoptera are particularly well-suited to study neuroplasticity, because the division of labor amongst females and the different life histories of males and females are as...

When acoustic communication signals are distorted, receivers may misunderstand the signal, rendering it ineffective. Common cuckoos (Cuculus canorus) are popularly known for the males' simple, two-note advertisement calls, the "cu-coo" used for declaring the male's breeding territories. Cuckoos do not learn their calls (vocal non-learners), so they...

Animals with dependent and vulnerable young need to decide where to raise their offspring to minimize ill effects of weather, competition, parasitism, and predation. These decisions have critical fitness consequences through impacting the survival of both adults and progeny. Birds routinely place their nest in specific sites, allowing species to be...

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. Earl...

Obligate insect social parasites evolve traits to effectively locate and then exploit their hosts, whereas hosts have complex social behavioral repertoires, which include sensory recognition to reject potential conspecific intruders and heterospecific parasites. While social parasites and host behaviors have been studied extensively, less is known...

Obligate insect social parasites evolve traits to effectively locate and then exploit their hosts, whereas hosts have complex social behavioral repertoires, which include sensory recognition to reject potential conspecific intruders and heterospecific parasites. While social parasite and host behaviors have been studied extensively, less is known a...

Phenotypic plasticity is the capacity of a single genotype to exhibit different phenotypes, and can be an adaptive response to specific environmental and social conditions. Social insects are particularly well-suited to study plasticity, because the division of labor amongst females and the different life histories of males and females are associat...

Movement of the embryo is essential for musculoskeletal development in vertebrates, yet little is known about whether, and why, species vary. Avian brood parasites exhibit feats of strength in early life as adaptations to exploit the hosts that rear them. We hypothesized that an increase in embryonic movement could allow brood parasites to develop...

Animals with dependent and vulnerable young need to decide where to raise their offspring to minimize ill effects of weather, competition, parasitism, and predation. These decisions have critical fitness consequences through impacting the survival of both adults and juveniles. Birds routinely place their nest in specific sites, allowing species to...