Memory Performance Influences Male Reproductive Success in a Wild Bird

© 2019 Elsevier Ltd Despite decades of comparative research, how selection shapes the evolution of cognitive traits remains poorly understood [1–3]. Several lines of evidence suggest that natural selection acts on spatial memory in food-caching species [3–6]. However, a link between reproductive fitness and spatial memory ability has yet to be demonstrated in any caching species [1, 3, 6]. Here, we show that memory performance influences reproductive success differentially for males and females in a caching songbird, the New Zealand robin (Petroica longipes). Males’ memory performance in a spatial task during winter influenced their subsequent breeding success; individuals with more accurate performance produced more fledglings and independent offspring per nesting attempt. Males with superior memory performance also provided an increased proportion of large prey items to chicks in the nest and spent less time flying while foraging and provisioning. No such effects were found for females. Previous research reveals that trade-offs may constrain selection and act to maintain variation in cognitive traits [7]. The gender dimorphism in the reproductive benefits of robin memory performance suggests an additional role for divergent selection between the sexes in constraining runaway selection on male memory ability [8], ultimately maintaining variation in this cognitive trait. Shaw et al. investigate whether spatial memory performance influences reproductive success in a food-caching bird, the New Zealand robin. The sexes differ in the reproductive and behavioral consequences of memory performance, suggesting that divergent selection between the sexes may constrain selection and maintain cognitive variation in the wild.

Memory Performance Influences Male Reproductive Success in a Wild Bird

© 2019 Elsevier Ltd Despite decades of comparative research, how selection shapes the evolution of cognitive traits remains poorly understood [1–3]. Several lines of evidence suggest that natural selection acts on spatial memory in food-caching species [3–6]. However, a link between reproductive fitness and spatial memory ability has yet to be demonstrated in any caching species [1, 3, 6]. Here, we show that memory performance influences reproductive success differentially for males and females in a caching songbird, the New Zealand robin (Petroica longipes). Males’ memory performance in a spatial task during winter influenced their subsequent breeding success; individuals with more accurate performance produced more fledglings and independent offspring per nesting attempt. Males with superior memory performance also provided an increased proportion of large prey items to chicks in the nest and spent less time flying while foraging and provisioning. No such effects were found for females. Previous research reveals that trade-offs may constrain selection and act to maintain variation in cognitive traits [7]. The gender dimorphism in the reproductive benefits of robin memory performance suggests an additional role for divergent selection between the sexes in constraining runaway selection on male memory ability [8], ultimately maintaining variation in this cognitive trait. Shaw et al. investigate whether spatial memory performance influences reproductive success in a food-caching bird, the New Zealand robin. The sexes differ in the reproductive and behavioral consequences of memory performance, suggesting that divergent selection between the sexes may constrain selection and maintain cognitive variation in the wild.

New Zealand Modernism

The moniker "New Zealand Modernism" is most frequently used today to describe art and architecture produced in New Zealand from the 1930s through the 1960s and beyond: for example, the paintings of Colin McCahon, Rita Angus, Gordon Walters, and Frances Hodgkins and the architecture of Ernst Plischke, Bill Toomath, Miles Warren, Maurice Mahoney, Humphrey Hall, and the Group architects. In literary studies, by contrast, the only New Zealand authors consistently labelled "modernists" are those who left home to anchor themselves in intellectual currents abroad: Katherine Mansfield, who wrote most of her New Zealand-themed stories from self-imposed exile in England and France; Lola Ridge, who represented herself in later life as an Australian-American poet despite, having spent 23 formative years in New Zealand; Robin Hyde, whose longing to see a wider world took her to war-torn China in the late 1930s. Yet, New Zealand literature from the 1920s onward was deeply influenced by Anglo-European modernism, often in ways that belie its seemingly provincial character and realist bias.

Avian translocations and disease; implications for New Zealand conservation

There is little published information on the pathogens present in New Zealand passerines. We report here on a preliminary survey of selected pathogens and haematology profiles for seven species in the Auckland region. Avian translocations are commonly used for the recovery of threatened species. Translocations may increase the risk of spreading disease to immunologically na�ve populations. It is therefore important to take every opportuntty to gather baseline disease data and test hypotheses associated with disease. Blood, cloacal and faecal samples were collected from Fernbird Bowdleria punctata, Tui Prosthemadera novaeseelandiae, Bellbird Anthornis melanura, Tomtit Petroica macrocephala, New Zealand Robin Petroica australis, Whitehead Mohua albicilla and Starling Sturnus vulgaris during four translocations to and from Tiritiri Matangi Island. Birds (n = 137) were also examined for external lesions typical of avian pox. Blood samples (n = 40) were screened by microscopy for Plasmodium spp., Atoxoplasma spp. and other blood parasites and a differential white blood cell count was made. Cloacal swabs (n = 38) were cultured for Yersinia spp., Salmonella spp. and Campyobaeter spp. Faecal samples were screened for coccidia spp. (n = 28). An unidentified coccidian sp. and a Haemoproteus sp. were detected in one Fembird and one robin respectively. No other organisms with the potential to cause disease were detected. Despite the effort required to complete disease screening, we argue that disease samples and baseline haematology normal values should be collected at an opportunities. We make recommendations for future disease screening, and discuss the importance and potential significance of disease to the conservation of New Zealand's biodiversity.

Frequency of Egg Rejection by Potential Hosts of the New Zealand Cuckoos

Host-specific brood parasites use a limited diversity of host species to raise their young. The two species of parasitic cuckoo that occur in New Zealand, Shining Cuckoo (Chrysococcyx lucidus) and Long-tailed Cuckoo (Eudynamys taitensis), are both host specific despite the availability of other apparently suitable species to act as hosts. To determine if host specificity has been shaped by the widespread occurrence of egg rejection among potential hosts, I tested the response of nine native passerine species to brood parasitism by the experimental addition of artificial cuckoo eggs to their nests. Artificial Shining Cuckoo eggs were rejected at least some of the time in eight of nine species tested, but levels of rejection were generally low. The majority of hosts accepted artificial Long-tailed Cuckoo eggs, and only the Brown Creeper (Mohoua novaeseelandiae) rejected eggs of both cuckoos. The occurrence of egg rejection in species currently not used as hosts (e.g., New Zealand Robin [Petroica australis]) suggests that they may have been parasitized by cuckoos in the past. Although egg rejection appears to limit the number of species currently suitable as hosts, it is not clear why acceptor species such as Fantails (Rhipidura fuliginosa) and Bellbirds (Anthornis melanura) are rarely parasitized, nor why egg mimicry as a counteradaptation to rejector species such as Brown Creepers and the New Zealand Pipit (Anthus novaeseelandiae) is poorly developed. On islands with depauperate avifaunas such as New Zealand, it is possible that the evolution of antiparasite adaptations in a small number of potential hosts may restrict the ability of brood parasites to evolve generalist strategies of host use. Frecuencia de Rechazo de Huevos por Hospederos Potenciales de los Cucos de Nueva Zelanda Resumen. Los parásitos de cría hospedero-específico utilizan una diversidad limitada de especies hospederas para criar a sus pichones. Las dos especies de cucos parásitos que se encuentran en Nueva Zelanda, Chrysococcyx lucidus y Eudynamys taitensis, son hospedero-específicas a pesar de la disponibilidad de otras especies aparentemente apropiadas para servir como hospederas. Para determinar si la especificidad de hospedero ha sido moldeada por una alta frecuencia de rechazo de huevos por parte de los hospederos potenciales, puse a prueba la respuesta de nueve especies de paserinos nativos ante el parasitismo de cría añadiendo huevos de cucos en sus nidos experimentalmente. Los huevos artificiales de C. lucidus fueron rechazados al menos algunas veces en ocho de las nueve especies estudiadas, pero los niveles de rechazo fueron generalmente bajos. La mayoría de los hospederos aceptaron los huevos artificiales de E. taitensis, y sólo Mohoua novaeseelandiae rechazó los huevos de ambos cucos. La ocurrencia de rechazo de huevos en especies no utilizadas actualmente como hospederos (e.g., Petroica australis) sugiere que éstas podrían haber sido parasitadas por cucos en el pasado. Aunque el rechazo de huevos parece limitar el número de especies actualmente apropiadas para servir como hospederas, no es claro por qué especies que aceptan los huevos (como Rhipidura fuliginosa y Anthornis melanura) son raramente parasitadas, ni por qué está poco desarrollado el mimetismo de huevos como una contra-adaptación ante especies que rechazan los huevos (como M. novaeseelandiae y Anthus novaeseelandiae). En islas con avifaunas empobrecidas como Nueva Zelanda, es posible que la evolución de adaptaciones antiparásitos en un pequeño número de hospederos potenciales restrinja la habilidad de los parásitos de cría para evolucionar hacia estrategias generalistas de uso de hospederos.