Innate versus learned recognition of conspecifics in great spotted cuckoos Clamator glandarius

When birds raised by another species become adults, they (if they are non-brood-parasitic species) usually attempt to mate with birds of their foster species rather than with birds of their own species, a phenomenon called sexual imprinting. Avian brood parasites lay their eggs in nests of other species (the hosts) that rear the young, but the problem of sexual imprinting among brood parasites has generally been neglected, and brood parasites have been considered as an exception among birds. Here, we show, with data from field observations and field experiments, firstly, that adult great spotted cuckoos Clamator glandarius sometimes maintain contact with both older nestling and fledgling cuckoos. Adult cuckoos visited parasitized nests during the last days of the nestling period (5 observations) and, when parasitic chicks left the nest, adult cuckoos maintained contact with the young (14 observations). Adults and fledgling cuckoos communicated vocally (5 observations), and an adult great spotted cuckoo even fed a parasite fledgling in two cases. Secondly, when experimentally cross-fostered in nests of magpie Pica pica hosts outside the parasite breeding range (thus avoiding visual and acoustic communication with adult cuckoos), young cuckoos did not learn to recognize their own species when only one cuckoo chick was introduced per nest, but they learnt to recognize conspecifics when two cuckoos were reared together. This means that young great spotted cuckoos apparently must learn to recognize conspecifics, that is, recognition is not innate. Social interactions between adult brood parasites and young have also been reported in other brood parasites; thus, brood parasites are probably not an exception to the general phenomenon of imprinting, and young brood parasites may need to be imprinted on conspecifics, although more studies on other brood parasite species are needed to confirm this. Received: 7 January 1999 / Accepted after revision: 27 February 1999     

Nest size matters: common cuckoos prefer to parasitize larger nests of Oriental reed warblers

Animal Cognition - Avian brood parasites leave parental care of their offspring to foster parents. Theory predicts that parasites should select for large host nests when they have sufficient...     

Do avian brood parasites eavesdrop on heterospecific sexual signals revealing host quality? A review of the evidence

Eavesdropping can be defined as the extraction of information from the interactions between other individuals. It provides a relatively cheap way of gathering relevant information for fitness enhancement. Here, we propose that obligate avian brood parasites, which always lay their eggs in foreign nests of individuals of other species, may eavesdrop on their host sexual signals to locate nests of high quality individuals in which to lay their parasitic eggs. Sexual signal variation can honestly signal parental quality. Thus, by eavesdropping on sexual signals, parasites may select high quality foster parents for their own offspring. Such a use of sexual signals within host populations by brood parasites differs from signal exploitation theory that proposes that parasite only use signals to locate potential host independently from signaller quality. Here, we review the avian literature concerning host choice within a host species by obligate avian brood parasites and find evidence for host selection within individuals of a host species on the basis of cues potentially functioning as sexually selected traits, or at least revealing parental abilities. We have also found support for the existence of benefits linked to host selection by avian brood parasites. Finally, one study reported on the attenuation of a sexual ornament in host populations under strong pressure by brood parasites. Most of these findings have been interpreted as evidence for host selection by avian brood parasites based on the conspicuousness of sexual signals. We suggest, however, that these findings may in fact reveal eavesdropping on host signalling performance by brood parasites which would use the information extracted to choose the better individuals among conspecifics of a given host. This provides a new perspective for the study of host selection in obligate brood parasites, and raises interesting questions for the study of animal cognition that would deserve experimental studies.     

Parasitic egg rejection decisions of chalk-browed mockingbirds <Emphasis Type="Italic">Mimus saturninus</Emphasis> are independent of clutch composition

Obligate avian brood parasites lay their eggs in nests of other host species, which assume all the costs of parental care for the foreign eggs and chicks. The most common defensive response to parasitism is the rejection of foreign eggs by hosts. Different cognitive mechanisms and decision-making rules may guide both egg recognition and rejection behaviors. Classical optimization models generally assume that decisions are based on the absolute properties of the options (i.e., absolute valuation). Increasing evidence shows instead that hosts’ rejection decisions also depend on the context in which options are presented (i.e., context-dependent valuation). Here we study whether the chalk-browed mockingbird’s (Mimus saturninus) rejection of parasitic shiny cowbird (Molothrus bonariensis) eggs is a fixed behavior or varies with the context of the clutch. We tested three possible context-dependent mechanisms: (1) range effect, (2) habituation to variation, and (3) sensitization to variation. We found that mockingbird rejection of parasitic eggs does not change according to the characteristics of the other eggs in the nest. Thus, rejection decisions may exclusively depend on the objective characteristics of the eggs, meaning that the threshold of acceptance or rejection of a foreign egg is context-independent in this system.     

Conflict between egg recognition and egg rejection decisions in common cuckoo (<Emphasis Type="Italic">Cuculus canorus</Emphasis>) hosts

Common cuckoos (Cuculus canorus) are obligate brood parasites, laying eggs into nests of small songbirds. The cuckoo hatchling evicts all eggs and young from a nest, eliminating hosts’ breeding success. Despite the consistently high costs of parasitism by common cuckoos, great reed warbler (Acrocephalus arundinaceus) hosts sometime accept and other times reject parasitic eggs. To explore the cognitive basis of this seemingly maladaptive variation in host responses, we documented differences in egg rejection rates within 1-day periods just before and during the egg-laying cycle across host nests. Hosts rejected cuckoo eggs at 28% of nests during the pre-egg-laying stage, but when cuckoos exchanged the first host egg with the parasite egg, rejections increased to 75%. Even later, when several host eggs remained in a nest after parasitism, rejection rate fell to 37.5%. Experimental parasitism with conspecific eggs on the first and second day of host laying showed a similar directional change in relative rejection rates, dropping from 35 to 0%. Mistakes in egg discrimination (ejection error and ejection cost) were observed mostly in the latter part of the laying cycle, mainly when nests contained 5–6 eggs. These correlational and experimental patterns of egg rejection support a cognitive process of egg discrimination through several shifts in hosts’ optimal acceptance thresholds of foreign eggs. The results are also consistent with the evolution of foreign egg rejection in the context of nest-sanitation (i.e. the removal of foreign objects). Our results suggest that common cuckoo hosts may recognize more eggs than they reject. This implies that the experience of the host with one or more of its own eggs in the clutch is a key factor in rejecting parasite eggs by allowing inspection and learning about their own clutch.     

Counting Chicks Before They Hatch: Female Cowbirds Can Time Readiness of a Host Nest for Parasitism

ABSTRACT— Here we show that demands associated with brood parasitism have favored sophisticated cognitive abilities in female brown-headed cowbirds. We discovered that cowbirds can use the rate at which eggs are added to a nest across days to assess the readiness of the nest for incubation, which would allow them to synchronize laying with the host and avoid nests where incubation has most likely commenced. In three experiments, cowbirds investigated and laid eggs in artificial nests that differed in the number of eggs they contained. Across days, we added eggs to nests at different rates to simulate differences in the timing of reproduction of the hosts. Cowbirds avoided a nest if the number of eggs that had been added was less than the number of days that had elapsed. The ability of females to remember egg number and compare changes in egg number across days allows them to select nests most suitable for parasitism.     

Self-referent phenotype matching in a brood parasite: the armpit effect in brown-headed cowbirds (Molothrus ater)

Most birds and mammals learn characteristics of conspecifics from their parents and siblings. In interspecific brood parasites, however, early social learning could lead to species recognition errors because young are reared among heterospecifics. Conceivably, juvenile parasites might inspect and memorize aspects of their own phenotype, and later match features of encountered individuals to that template. We tested for such self-referent phenotype matching by manipulating feather colors of hand-reared fledglings (n = 21) of the parasitic brown-headed cowbird (Molothrus ater). In simultaneous choice trials (n = 6 trials/subject) between dyed and normal-colored adult females, juvenile cowbirds (< 2 months old) approached more quickly and associated preferentially with individuals that were colored similar to themselves. These preferences remained even when differences between the associative behaviors of juvenile males and females were controlled statistically. Our data imply that cowbirds incorporate their own plumage color into their recognition template. This provides the first evidence of self-referent phenotype matching through experimental manipulation of a recognition cue. Received: 11 April 2000 / Accepted after revision: 2 September 2000     

Sexual differences in memory in shiny cowbirds

Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male’s assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood. Received: 30 April 1998 / Accepted after revision: 5 September 1998     

Different recognition cues reveal the decision rules used for egg rejection by hosts of a variably mimetic avian brood parasite

Brood parasitism imposes several fitness costs on the host species. To reduce these costs, hosts of avian brood parasites have evolved various defenses, of which egg rejection is the most prevalent. In the face of variable host-parasite mimicry and the costs of egg discrimination itself, many hosts reject only some foreign eggs. Here, we experimentally varied the recognition cues to study the underlying cognitive mechanisms used by the Chalk-browed Mockingbird (Mimus saturninus) to reject the white immaculate eggs laid by the parasitic Shiny Cowbird (Molothrus bonariensis). Immaculate eggs are the only parasite eggs rejected by this host, as it accepts all polymorphic, spotted eggs laid by cowbirds. Using a within-breeding pair experimental design, we tested for the salience of spotting, UV reflectance, and brightness in eliciting rejection. We found that the presence of spotting significantly decreased the probability of rejection while increments in brightness significantly increased rejection frequencies. The cognitive rules underlying mockingbird rejection behavior can be explained by a decision-making model which predicts changes in the levels of rejection in direct relation to the number of relevant attributes shared between host and parasite eggs.     

Acoustic interactions in broods of nestling birds (Tachycineta bicolor)

Studies of acoustic interactions in animal groups, such as chorusing insects, anurans, and birds, have been invaluable in showing how cooperation and competition shape signal structure and use. The begging calls of nestling birds are ideal for such studies, because they function both as a cooperative signals of the brood's needs and as competitive signals for parental allocation within the brood. Nonetheless, studies of acoustic interactions among nestlings are rare. Here we review our work on acoustic interactions in nestling tree swallows (Tachycineta bicolor), especially how calls are used in competition for parental feedings. Nestlings attracted parental attention and responded to acoustic interference mainly by increasing call output. However, nestlings also gave more similar calls when they called together and decreased their call bandwidth when exposed to elevated noise. We suggest that these competitive uses of calls might intensify the cooperative brood signal, affecting both parental provisioning and vocal development. Given their tremendous variation across species, begging calls offer promising opportunities for developmental and comparative studies of acoustic signaling.     

Egg arrangement in avian clutches covaries with the rejection of foreign eggs

In birds, the colour, maculation, shape, and size of their eggs play critical roles in discrimination of foreign eggs in the clutch. So far, however, no study has examined the role of egg arrangement within a clutch on host rejection responses. We predicted that individual females which maintain consistent egg arrangements within their clutch would be better able to detect and reject foreign eggs than females without a consistent egg arrangement (i.e. whose eggs change positions more often across incubation). We tested this “egg arrangement hypothesis” in blackbirds (Turdus merula) and song thrush (T. philomelos). Both species are suitable candidates for research on egg rejection, because they show high inter-individual variation and individual repeatability in egg rejection responses. As predicted, using our custom-defined metrics of egg arrangement, rejecter females’ clutches showed significantly more consistent patterns in egg arrangement than acceptor females’ clutches. Only parameters related to blunt pole showed consistent differences between rejecters and acceptors. This finding makes biological sense because it is already known that song thrush use blunt pole cues to reject foreign eggs. We propose that a disturbance of the original egg arrangement pattern by the laying parasite may alert host females that maintain a consistent egg arrangement to the risk of having been parasitized. Once alerted, these hosts may shift their discrimination thresholds to be more restrictive so as to reject a foreign egg with higher probability. Future studies will benefit from experimentally testing whether these two and other parasitized rejecter host species may rely on the use of consistent egg arrangements as a component of their anti-parasitic defence mechanisms.     

Discrimination between host songs by brood parasitic brown-headed cowbirds ( Molothrus ater)

Songbirds can learn both to produce and to discriminate between different classes of acoustic stimuli. Varying levels of auditory discrimination may improve the fitness of individuals in certain ecological and social contexts and, thus, selection is expected to mold the cognitive abilities of different species according to the potential benefits of acoustic processing. Although fine-scale auditory discrimination of conspecific songs and calls has been frequently reported for brood parasitic brown-headed cowbirds (Molothrus ater), it remains unclear why and how they perceive differently the songs of their many host species. Using habituation-dishabituation paradigms and measuring behavioral and physiological (heart-rate) responses, we found that captive female cowbirds consistently discriminated between songs of two host species, the song sparrow (Melospiza melodia) and the red-winged blackbird (Agelaius phoeniceus). Playback experiments with stimuli composed of con-specific followed by heterospecific vocalizations in the field also demonstrated discrimination between these heterospecific songs even though cowbirds were not attracted to playbacks of either host species' songs alone. Our results do not directly support a nest-searching function of heterospecific song discrimination by cowbirds and are most consistent with a function of the parasites' avoidance of attacks by their agressive hosts. These data demonstrate discrimination between heterospecific vocalizations by brown-headed cowbirds and add a novel dimension to the already expansive auditory perceptual abilities of brood parasitic species and other songbirds. Electronic Publication     

How to avoid begging the question against evolutionary debunking arguments

Evolutionary debunking arguments aim to undercut the epistemological status of our evaluative beliefs on the basis of the genesis of our belief‐forming tendencies. This paper addresses the issue whether responses to these arguments must be question‐begging. It argues for a pragmatic understanding of question‐beggingness, according to which whether an argument is question‐begging depends on the argumentative context. After laying out the debunking argument, the paper considers a variety of responses. It asks whether metaethical responses, such as Sharon Street’s response that relies on a version of antirealism, can avoid begging the question. It argues that so‐called ‘third‐factor’ responses, which rely on substantive evaluative views, are not question‐begging in all contexts. Similarly, it argues, my own ‘quasi‐tracking’ response is not question‐begging in all contexts. Finally, the paper asks whether responses to the debunking argument can avoid begging the question against someone who is convinced at the outset that the argument is sound.     

Parasites of the mind. Why cultural theorists need the meme’s eye view

Are there any such things as mind parasites? By analogy with biological parasites, such cultural items are supposed to subvert or harm the interests of their host. The hypothesis of cultural parasitism has appeared in different guises in the burgeoning field of cultural evolution. To unpack the notion of mind parasites, we first clear some conceptual ground around the concept of cultural adaptation and its relation to human agency. We then formulate Millikan’s challenge: how can cultural items develop novel purposes of their own, cross-cutting or subverting our own personal purposes? If this central challenge is not met, talk of cultural ‘parasites’ or ‘selfish memes’ remains vacuous. First, we discuss why other attempts to answer Millikan’s challenge have failed. In particular, we put to rest the claims of panmemetics, a somewhat sinister worldview according to which human culture is nothing more than a swarm of selfish agents, plotting and scheming behind the scenes. Next, we reject a more reasonable, but still overly permissive approach to mind parasites, which equates them with biologically maladaptive culture. Finally, we present our own answer to Millikan’s challenge: certain systems of misbelief can be fruitfully treated as cultural parasites, designed by cultural evolution to subvert the interests of their human hosts. As a proof of concept, we discuss witchcraft beliefs in early modern Europe, and show how the meme’s eye view promises to shed new light on a mystery that historians and social scientists have been wrestling with for decades.     

Foster Care Placement,Poor Parenting,and Negative Outcomes Among Homeless Young Adults

Although homeless youth with and without foster care histories both face adverse life circumstances, little is known about how these two groups compare in terms of their early histories and whether they face similar outcomes. As such, we compared those with and without a history of foster care placement to determine if the associations between a history of poor parenting and negative outcomes including depression, delinquency, physical and sexual victimization, and substance use, are similar for these two groups. The sample consisted of 172 homeless young adults from the Midwestern United States. Multivariate results revealed that among those previously in foster care, a history of physical abuse and neglect were positively associated with more depressive symptoms whereas sexual abuse and neglect were related to delinquency and physical victimization. Additionally, lower caretaker monitoring was linked to greater delinquent participation. Among those without a history of foster care, physical abuse was related to more depressive symptoms whereas sexual abuse was positively correlated with delinquency, sexual victimization, and substance use. Furthermore, lower monitoring was related to more substance use. Our findings are discussed in terms of a social stress framework and we review the implications of foster care placement for homeless young adults.     

Development of an Intervention for Foster Parents of Young Foster Children with Externalizing Behavior: Theoretical Basis and Program Description

Foster parents are often faced with serious externalizing behaviors of their foster child. These behavioral problems may induce family stress and are related to less effective parenting and often increase. Foster children with behavioral problems are also more at risk of placement breakdown. An intervention to support foster parents of young foster children with externalizing behaviors is necessary to improve the effectiveness of foster placements. Based on research on effective parenting interventions and special needs of foster children, a treatment protocol was developed. This paper describes theoretical foundations for the content and form of the intervention and gives an overview of the modular treatment protocol. Preliminary outcomes of this intervention as well as challenges and future developments and research activities are discussed.     

Kin recognition loss following anesthesia in beetle larvae (Aleochara bilineata, Coleoptera, Staphylinidae)

Kin recognition is a complex cognitive process, where an individual should detect a phenotypic cue and compare it to an internal template, which might be genetically determined (i.e., innate or acquired). Kin recognition mechanisms will depend on whether previous encounters with kin are possible or not to form the individual internal template. When relatives have never met before, kin recognition is supposed to rely on recognition alleles (which allows the innate recognition of relatives bearing them), or on self-referent phenotype matching (the individual has formed a template using its own phenotype and recognizes as kin individuals which match it closely enough). Although self-referent phenotype matching is in theory the more likely explanation, it has not been possible so far to exclude experimentally the recognition alleles’ hypothesis. Here, we report that kin recognition in the solitary parasitoid larvae of Aleochara bilineata (Coleoptera; Staphylinidae) is suppressed following carbon dioxide anesthesia or chill-coma, both treatments known to cause a temporary amnesia. Treated larvae superparasitize indifferently hosts parasitized either by siblings or by non-kin larvae, while untreated larvae avoid hosts occupied by siblings. The two types of anesthesia thus suppress kin recognition, but their global effect on larvae is different. Chill-coma suppresses the ability to distinguish parasitized from unparasitized hosts and reduces parasitism rate, suggesting an aspecific impairment of sensory receptors or cognition. However, carbon dioxide narcosis only impairs kin recognition, strongly suggesting that an intact memory is necessary for kin recognition to take place. Although this study does not address the recognition alleles’ hypothesis per se, our results strongly support a self-referent phenotype matching mechanism. On the whole, kin recognition in A. bilineata larvae is effective through short-term memory, because it is affected by amnesic treatments.     

The rescue of Jewish girls and teenage women to England and the USA during the Holocaust: a gendered perspective

This article deals with the lives and experiences of refugee girls and young women who found refuge in England and the United States during the Holocaust. Between 1934 and 1945 more than 12,600 unaccompanied children and teenagers from Central Europe between the ages of five and sixteen were shielded from Nazism in the Great Britain or the United States. In addition, approximately 1000 Jewish refugee children were brought to the United States by various refugee organizations prior to and during the war years. The experiences of girls and young women in this group were different than those of boys and young men, particularly with respect to foster parent preferences, immigration, resettlement and adaptation, treatment in the foster home, professional choices, and assimilation into a new society. This article discusses these differences from the standpoint of identity construction, socio-cultural adjustment problems and alienation-assimilation dialectics.     

Nestling recognition via direct cues by parental male bluegill sunfish (<Emphasis Type="Italic">Lepomis macrochirus</Emphasis>)

Parental care can be costly to a parent in terms of both time and energy invested in the young. In species with cuckoldry or brood parasitism not all of the young under a parent's care are necessarily offspring. In such cases, distinguishing between kin and non-kin, and investing only in the former (nepotism), can be advantageous. Bluegill sunfish (Lepomis macrochirus) are characterized by paternal care and cuckoldry, and care-providing males appear to show nepotistic behaviours. Here, we investigated nestling recognition in bluegill, determining whether parental males can differentiate between young from their own nest (familiar and related) and young from non-neighbouring nests (unfamiliar and unrelated) using (1) visual and chemical cues, and (2) chemical cues only. In the first experiment, wild-caught parental males were presented with samples of eggs or fry (newly hatched eggs) collected from their own nest or a foreign nest and placed on opposite sides of an aquarium. The time these parental males spent associating with each sample, and their "pecking" behaviours (indicating cannibalism), were recorded. Parental males showed no preference between eggs from their own nest and eggs from a non-neighbouring nest, but they preferred to associate with fry from their own nest over foreign fry. There also was a positive relationship between male body size and the time spent associated with fry from their own nest. Parental males pecked at foreign fry more than 5 times as often as fry from their own nest, though this difference was not statistically significant. In the second experiment, fry that were collected from the nest of a wild-caught parental male or a non-neighbouring nest were placed in different containers and the water from each was dripped into opposite ends of an aquarium. The time the male spent on each side was recorded. In this case, parental males spent more time near the source of water conditioned by unrelated fry, but there was a positive relationship between male condition (fat reserves) and the time he spent near the source of water conditioned by fry from his own nest. Results confirm that chemicals cue nestling recognition by parental male bluegill. Electronic Publication     

A systematic review of cognitive functioning among young people who have experienced homelessness,foster care,or poverty

Young people who have experienced homelessness, foster care, or poverty are among the most disadvantaged in society. This review examines whether young people who have these experiences differ from their non-disadvantaged peers with respect to their cognitive skills and abilities, and whether cognitive profiles differ between these three groups. Three electronic databases were systematically searched for articles published between 1 January 1995 and 1 February 2015 on cognitive functioning among young people aged 15 to 24 years who have experienced homelessness, foster care, or poverty. Articles were screened using pre-determined inclusion criteria, then the data were extracted, and its quality assessed. A total of 31 studies were included. Compared to non-disadvantaged youth or published norms, cognitive performance was generally found to be impaired in young people who had experienced homelessness, foster care, or poverty. A common area of difficulty across all groups is working memory. General cognitive functioning, attention, and executive function deficits are shared by the homeless and poverty groups. Creativity emerges as a potential strength for homeless young people. The cognitive functioning of young people with experiences of impermanent housing and poverty has been relatively neglected and more research is needed to further establish cognitive profiles and replicate the findings reviewed here. As some aspects of cognitive functioning may show improvement with training, these could represent a target for intervention.