Michael G. Anderson

Breeding-season survival of mallard females in the prairie pothole region of Canada

As part of the Prairie Habitat Joint Venture (PHJV) Habitat Assessment Project, we radiomarked and tracked daily 2,249 female mallard ducks (Anas platyrhynchos) in the Prairie Pothole Region (PPR) of Canada. We conducted our study at 19 different 54- to 78-km 2 sites for 1 year per site from 1993 to 1998. We estimated female survival probability during the 90-day period following arrival on the breeding area and employed information-theoretic approaches to select among competing models that described factors affecting survival probability. We investigated the relationship between female survival and 3 periods of the nesting season, female age (yearling vs. older), upland habitat treatments, longitude, and habitat variables. Our model estimates of female survival probability ranged between 0.62 (SE = 0.028) and 0.84 (SE = 0.018) and averaged 0.76 (SE = 0.004) for the 90-day period. The best approximating model indicated that female survival was (1) lowest when most females were nesting, and (2) depended on longitude and percent wetland habitat such that survival was lowest at western sites with low wetland densities. Management efforts to reduce wetland loss, especially in western regions of the Canadian PPR, may positively influence female survival. Upland habitat restorations designed to improve nest survival may not have a concurrent impact on female survival unless a significant portion of the nesting population is affected.

Ultraviolet visual sensitivity in three avian lineages: paleognaths, parrots, and passerines

Ultraviolet (UV) light-transmitted signals play a major role in avian foraging and communication, subserving functional roles in feeding, mate choice, egg recognition, and nestling discrimination. Sequencing functionally relevant regions of the short wavelength sensitive type 1 (SWS1) opsin gene that is responsible for modulating the extent of SWS1 UV sensitivity in birds allows predictions to be made about the visual system’s UV sensitivity in species where direct physiological or behavioral measures would be impractical or unethical. Here, we present SWS1 segment sequence data from representative species of three avian lineages for which visually based cues for foraging and communication have been investigated to varying extents. We also present a preliminary phylogenetic analysis and ancestral character state reconstructions of key spectral tuning sites along the SWS1 opsin based on our sequence data. The results suggest ubiquitous ultraviolet SWS1 sensitivity (UVS) in both paleognaths, including extinct moa (Emeidae), and parrots, including the nocturnal and flightless kakapo (Strigops habroptilus), and in most, but not all, songbird (oscine) lineages, and confirmed violet sensitivity (VS) in two suboscine families. Passerine hosts of avian brood parasites were included both UVS and VS taxa, but sensitivity did not co-vary with egg rejection behaviors. The results should stimulate future research into the functional parallels between the roles of visual signals and the genetic basis of visual sensitivity in birds and other taxa.

Egg Eviction Imposes a Recoverable Cost of Virulence in Chicks of a Brood Parasite

Background Chicks of virulent brood parasitic birds eliminate their nestmates and avoid costly competition for foster parental care. Yet, efforts to evict nest contents by the blind and naked common cuckoo Cuculus canorus hatchling are counterintuitive as both adult parasites and large older cuckoo chicks appear to be better suited to tossing the eggs and young of the foster parents. Methodology/Principal Findings Here we show experimentally that egg tossing imposed a recoverable growth cost of mass gain in common cuckoo chicks during the nestling period in nests of great reed warbler Acrocephalus arundinaceus hosts. Growth rates of skeletal traits and morphological variables involved in the solicitation of foster parental care remained similar between evictor and non-evictor chicks throughout development. We also detected no increase in predation rates for evicting nests, suggesting that egg tossing behavior by common cuckoo hatchlings does not increase the conspicuousness of nests. Conclusion The temporary growth cost of egg eviction by common cuckoo hatchlings is the result of constraints imposed by rejecter host adults and competitive nestmates on the timing and mechanism of parasite virulence.

Bioacoustic distances between the begging calls of brood parasites and their host species: a comparison of metrics and techniques

A variety of bioacoustics distance metrics have been used to assess similarities in the vocalizations of different individuals. Here, we provide a detailed analysis of several acoustic similarity indices, some of which have been developed with the specific aim of characterizing the sensory coding of auditory stimuli. We compare different approaches through the analysis of begging calls of several passerine species and specialist brood parasitic cuckoos that putatively evolved to mimic their hosts. The different bioacoustics distances did not provide consistently correlated similarity patterns, implying that they are sensitive to different sound features. However, the encoded spectrogram alignment method was correlated with all other acoustic distance metrics, suggesting that this method provides a consistent approach to use when the perceptually salient sound parameters are unknown for a particular species. Our analyses confirm that statistical similarity of begging calls can be detected in a New Zealand pair of host and specialist parasite species. We also show detectable similarity in two other Australasian host–parasite pairs and another New Zealand system, but to a more limited extent. By examining phylogenetic patterns in the begging call diversity, we also confirm that specialist cuckoos have evolved to mimic the begging calls of their hosts but host species have not co-evolved to modify their calls in response to begging call similarity by the parasite. Our results illustrate that understanding the function and mechanism of behavioral copying and mimicry requires statistically consistent measures of similarity that are related to both the physical aspects of the particular display and the sensory basis of its perception.

Life-history theory predicts host behavioural responses to experimental brood parasitism

Life-history theory posits that the evolutionary responses of hosts to avian brood parasitism will be shaped by the extent of the fitness costs of parasitism. Previous modelling work predicted that hosts of more virulent parasites should eject foreign eggs, irrespective of clutch size, whereas hosts of less virulent parasites, with smaller clutch sizes, should desert (abandon) parasitized clutches and, with larger clutch sizes, should eject foreign eggs. Egg rejection behaviour of European blackbirds (Turdus merula) and song thrush (T. philomelos) in their introduced range in New Zealand was induced by manipulating the colour of one of the birds’ own eggs. We also used parallel experimental manipulations in the common redstart (Phoenicurus phoenicurus), a regular host species with a large clutch size which pays a moderate cost when parasitized by the common cuckoo (Cuculus canorus). In all three species, eggs coloured entirely black were more often rejected than eggs coloured with black spots but with the rest of the background colour left visible. Rejections of black eggs occurred mainly through nest desertion in blackbirds, which have smaller clutch sizes, and mainly through egg ejection in song thrush, which have larger clutch sizes. As predicted, redstarts mostly ejected black eggs. Alternative egg rejection behaviours may have evolved in response to differently virulent brood parasitism across these species. For example, in the absence of interspecific parasitism in both their native and introduced ranges, selection by low-cost intraspecific brood parasitism may explain the experimentally-induced behavioural differences in egg rejection in blackbirds, with smaller clutch sizes, versus song thrushes, with larger clutch sizes. Such experimental approaches, informed by life-history theory, should be generally useful in larger-scale, comparative frameworks, to determine the relative roles of intra- versus interspecific brood parasitism in the evolution of egg rejection behaviours across diverse avian lineages.

Competition with a host nestling for parental provisioning imposes recoverable costs on parasitic cuckoo chick's growth

Chicks of the brood parasitic common cuckoo (Cuculus canorus) typically monopolize host parental care by evicting all eggs and nestmates from the nest. To assess the benefits of parasitic eviction behaviour throughout the full nestling period, we generated mixed broods of one cuckoo and one great reed warbler (Acrocephalus arundinaceus) to study how hosts divide care between own and parasitic young. We also recorded parental provisioning behaviour at nests of singleton host nestlings or singleton cuckoo chicks. Host parents fed the three types of broods with similar-sized food items. The mass of the cuckoo chicks was significantly reduced in mixed broods relative to singleton cuckoos. Yet, after the host chick fledged from mixed broods, at about 10-12 days, cuckoo chicks in mixed broods grew faster and appeared to have compensated for the growth costs of prior cohabitation by fledging at similar weights and ages compared to singleton cuckoo chicks. These results are contrary to suggestions that chick competition in mixed broods of cuckoos and hosts causes an irrecoverable cost for the developing brood parasite. Flexibility in cuckoos growth dynamics may provide a general benefit to ecological uncertainty regarding the realized successes, failures, and costs of nestmate eviction strategies of brood parasites.

Latitudinal differences in the breeding phenology of Grey Warblers covary with the prevalence of parasitism by Shining Bronze-Cuckoos

Abstract Variation in the temporal patterns of nest availability through the breeding season or across the geographical range of a host is expected to be an important selection pressure shaping the breeding biology of avian brood parasites. The archipelago-wide distribution of the endemic Grey Warbler (Gerygone igata) in New Zealand, and its parasitism by the specialist Shining Bronze-Cuckoo (Chalcites lucidus), makes this a valuable system in which to study small-scale latitudinal gradients in host breeding phenology and the effects of these on the prevalence of brood parasitism. Nest records from throughout New Zealand and our study sites on both the North and South Islands indicated that, as expected, clutch-sizes were larger at higher, more southern, latitudes. Contrary to predictions, breeding began later and finished earlier, and usually involved only one brood on the North Island, compared with a longer breeding season with two broods on the South Island. Prevalence of brood parasitism covaried positively with latitude, suggesting that geographical patterns in breeding phenology of hosts may influence the prevalence of parasitism.

Innovative pandanus-tool folding by New Caledonian crows

The ratcheting of evolutionary innovations over time has enabled humans to produce complex technology. This process requires (1) technological innovations, (2) the accurate transmission of innovations by social learning, and (3) the faithful maintenance of new technology by its standardised reproduction. Although nonhuman primates are good behavioural innovators, there is no evidence that they have evolved cumulative technology. It has been previously suggested that New Caledonian crows have made cumulative changes to their pandanus tool manufacture. However, technological innovation by individual New Caledonian crows in the wild had not been observed. Here, we report that two distantly related male crows at the same location have a novel way of using pandanus tools by first folding them into a boomerang-like shape. The fine manipulation to fold tools was highly routinised and its two main manipulatory components (direction of head movement and holding technique) were exclusively lateralised. As a consequence the fold arrangement was invariable irrespective of a tool’s position before folding. The males’ tool-folding confirms that New Caledonian crows have a disposition to routinise and lateralise complex sequences of manipulatory actions. Such a disposition may facilitate the evolution of cumulative technology because it can act to standardise the reproduction of a technological innovation.

Social and habitat correlates of immigrant recruitment of yearling female Mallards to breeding locations

Conspecific avoidance and attraction hypotheses have been proposed to explain patterns of animal spacing behavior and have been frequently used to explain habitat selection by dispersers. In birds, tests of these hypotheses have been limited to fine spatial scales and have not considered dispersal distance. We used discriminant function analysis (DF) of feather δ34S, δD, δ15N and δ13C values to identify yearling female Mallards (Anas platyrhynchos) that dispersed long distances (>400xa0km relative latitude) from natal areas to settle at 22 breeding locations in the Canadian parklands, 1993–2000; these sites varied in social (breeding pair density) and breeding habitat (wetland density and percent nest cover) conditions. DF indicated that the proportion of yearling female recruits estimated to be long-distance immigrants in these breeding populations averaged 12% across sites (range 0–38%). Yearling immigration rates were positively correlated with conspecific breeding pair density and negatively correlated with percent wetland habitat. Settling patterns by yearling immigrants were most consistent with the prediction of social attraction, but effects were statistically weak possibly because inter-regional movements were less variable annually due to relatively stable wetland conditions in the southern prairies during the period of study. Our results suggest immigrants arriving from distant natal sites used conspecific abundance as a positive cue of habitat quality when choosing the new breeding sites. Fitness consequences of these choices should be evaluated.ZusammenfassungDie Vermeidung und die Anziehungskraft von Artgenossen werden oft zur Erklärung von räumlichem Verteilungsverhalten von Tieren herangezogen. Genauso wurden diese häufig verwandt, um die Habitatwahl von zugewanderten Individuen zu erklären. Untersuchungen, die diese Hypothesen testen, sind bei Vögeln allerdings auf relative kleine räumliche Skalen beschränkt, ebenso wird die zurückgelegte Distanz der Zuwanderung häufig nicht berücksichtigt. Wir bedienen uns einer Diskriminanzanalyse (DF) von δ34S, δD, δ15N und δ13C von Federn, um einjährige Stockentenweibchen (Anas platyrhynchos), die 1992–2000 weit entfernt von ihrem Geburtsort brüteten, zu identifizieren. Unsere 22 Untersuchungsgebiete in kanadischem Parkland variierten in der sozialen Brutpaardichte und in Bruthabitatparametern (Feuchtgebietdichte und Prozentsatz Nestabdeckung). Die DF zeigte, dass der Anteil weiblicher, einjähriger Ferneinwanderer bei 12% lag (Durchschnitt über alle Untersuchungsgebiete, Streubreite: 0–38%). Die Immigrationsrate dieser Einwanderer war positiv mit der Brutpaardichte und negativ mit dem Prozentsatz Feuchtgebiete assoziiert. Die Ansiedlungsmuster einjähriger Zuwanderer waren konsistent mit der Vorhersage der Hypothese der Anziehungskraft von Artgenossen, aber die Effekte waren statistisch nur schwach. Die Ursache hierfür liegt möglicherweise in der geringen Variation in den inter-regionale Bewegungen zwischen Jahren, welche daher stammt, dass einige Feuchtgebiete im Untersuchungszeitraum sehr stabil waren. Unsere Ergebnisse legen nahe, dass Zuwanderer von entfernten Gebieten die Abundanz von Artgenossen als positives Signal für Lebensraumqualität zukünftiger Brutstätten verwenden. In Zukunft sollten die Fitnesskonsequenzen hiervon evaluiert werden.

Phylogenetic relationships of the genus Mohoua , endemic hosts of New Zealand’s obligate brood parasitic Long-tailed Cuckoo ( Eudynamys taitensis )

AbstractThe three species of New Zealand’s endemic Mohoua genus are sole hosts of the obligate brood parasitic Long-tailed Cuckoo (Eudynamys taitensis), making their intrageneric phylogenetic relationships particularly important for coevolutionary studies. Also, recent molecular phylogenetic analyses have not identified the family-level placement of this genus. To resolve both intrageneric and family relationships, we generated new nuclear and mitochondrial sequence data and conducted phylogenetic analyses using Bayesian inference among representatives of endemic New Zealand passerines and Australasian ‘core Corvoidea’ lineages. The results establish strong intrageneric relationships of all three Mohoua species, confirm the monophyly of the genus, and suggest its placement in a re-erected monotypic family: Mohouidae.ZusammenfassungPhylogenetische Beziehungen der GattungMohuoa, endemische Wirte des neuseeländischen obligat brutparasitischen Langschwanzkoels (Eudynamys taitensis)n Die drei Arten der für Neuseeland endemischen Gattung Mohoua sind die alleinigen Wirte des obligat brutparasitischen Langschwanzkoels (Eudynamys taitensis), was die phylogenetischen Beziehungen innerhalb der Gattung besonders wichtig für co-evolutionäre Studien macht. Neuere molekulare phylogenetische Analysen erlaubten keine Einordnung dieser Gattung auf Familienebene. Um sowohl die Beziehungen innerhalb der Gattung als auch die Familienzugehörigkeit zu klären, haben wir neue Kern- und Mitochondrien-DNA-Sequenzdaten gewonnen und phylogenetische Analysen von Vertretern endemischer neuseeländischer Sperlingsvögel und australasiatischer „Core- Corvoidea“ mittels Bayesscher Statistik durchgeführt. Die Ergebnisse etablieren solide intragenerische Beziehungen aller drei Mohoua Arten, bestätigen die Monophylie der Gattung und schlagen ihre Einordnung in die wieder eingerichtete monotypische Familie Mohouidae vor.