The effects of nesting stage, sex, and type of predator on parental defense by killdeer ( Charadrius vociferous ): testing models of avian parental defense

Two models predicting the temporal patterns of parental investment in offspring defense over the nesting cycle were tested. The first is based on offspring age, the other on the vulnerability of offspring to predation. Both models make very similar predictions for altricial species after eggs have hatched, i.e., increases in intensity of parental defense until fledging. For precocial species, however, the post-hatching predictions of each model are different: the offspring age model predicts a continued increase in defense intensity, while the vulnerability model predicts a decline. I examined the temporal patterns of parental defense of a precocial shorebird, the killdeer ( Charadrius vociferus ), and determined which model was supported. Killdeer responses to human and natural predators were observed. Killdeer were less willing to leave the nest, responded most intensely, and displayed closest to a potential predator around hatching. Defense intensity increased from early to late incubation as predicted by the offspring age model. However, after hatching killdeer parental defense declined for both males and females, thus supporting the vulnerability model for this stage. Males and females responded significantly differently to all types of predators. Males took greater risks, remained on the nest longer, defended offspring more intensely, and displayed closer to the predator than females at the approach of a potential predator. Responses to natural predators depended on the type of predator and the approach made by the predator; a greater range of defense behavior was used for predators approaching on the ground compared to aerial predators. In general, killdeer responses to humans were more intense and less variable than their responses to natural predators. This was most likely because the human intruder approached nests and chicks more directly and closer than natural predators.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46896/1/265_2004_Article_BF00172085.pd

Biological invasions as a selective filter driving behavioral divergence

Biological invasions are a multi-stage process (i.e., transport, introduction, establishment, spread), with each stage potentially acting as a selective filter on traits associated with invasion success. Behavior (e.g., exploration, activity, boldness) plays a key role in facilitating species introductions, but whether invasion acts as a selective filter on such traits is not well known. Here we capitalize on the well-characterized introduction of an invasive lizard (Lampropholis delicata) across three independent lineages throughout the Pacific, and show that invasion shifted behavioral trait means and reduced among-individual variation-two key predictions of the selective filter hypothesis. Moreover, lizards from all three invasive ranges were also more behaviorally plastic (i.e., greater within-individual variation) than their native range counterparts. We provide support for the importance of selective filtering of behavioral traits in a widespread invasion. Given that invasive species are a leading driver of global biodiversity loss, understanding how invasion selects for specific behaviors is critical for improving predictions of the effects of alien species on invaded communities.Invasive species are a leading driver of global biodiversity loss. Here, the authors show that the process of invasion itself can promote behavioral changes important to the success of widespread invaders, with implications for understanding the effects of alien species on invaded communities

Haemoproteus minutus is highly virulent for Australasian and South American parrots

Background: Haemoproteus and Plasmodium species are widespread avian blood parasites. Several Plasmodium species are known for their high virulence and have caused significant declines in naïve bird populations. The impact of closely related Haemoproteus parasites is largely unknown. Recently we reported a lethal disease in two parrot aviaries caused by Haemoproteus parasites. Results: Here we show that the causative pathogen Haemoproteus minutus is responsible for further 17 lethal outbreaks in parrot aviaries in Denmark, Germany and Great Britain. All affected parrots are endemic to Australasia and South America. We sequenced the cytochrome b gene from megalomeront-infected muscle tissue of 21 parrots and identified the two lineages TUPHI01 and TURDUS2 as causative agents, commonly naturally infecting the common blackbird (Turdus merula) and the song thrush (Turdus philomelos), respectively, in the Palaearctic. No intraerythrocytic parasite stages were found in any of the parrots. We failed to detect H. minutus in invasive Indian ring-necked parakeets (Psittacula krameri) in Germany. Together this suggests that abortive infections with two virulent lineages of H. minutus are lethal for naïve parrot species from Australasia and South America. We asked whether we could detect H. minutus in New Zealand, where its Turdus hosts were introduced in the 1800s. We therefore tested invasive blackbirds and song thrushes, and the co-existing endemic red-fronted parakeet (Cyanoramphus novaezelandiae) population on three New Zealand islands. No Haemoproteus spp. DNA was detected in all blood samples, indicating absence of transmission. Conclusions: The results of this study show that captive parrots in Europe are threatened by two lineages of an otherwise benign parasite of Turdus spp. Aviary collections of parrots should be protected from Culicoides spp. vectors in Europe. Animal trade and climate changes extending the current vector and parasite distribution have to be considered as potential risk factors for the introduction of the disease in naïve parrot populations

Anatomical Specializations for Nocturnality in a Critically Endangered Parrot, the Kakapo (Strigops habroptilus)

The shift from a diurnal to nocturnal lifestyle in vertebrates is generally associated with either enhanced visual sensitivity or a decreased reliance on vision. Within birds, most studies have focused on differences in the visual system across all birds with respect to nocturnality-diurnality. The critically endangered Kakapo (Strigops habroptilus), a parrot endemic to New Zealand, is an example of a species that has evolved a nocturnal lifestyle in an otherwise diurnal lineage, but nothing is known about its' visual system. Here, we provide a detailed morphological analysis of the orbits, brain, eye, and retina of the Kakapo and comparisons with other birds. Morphometric analyses revealed that the Kakapo's orbits are significantly more convergent than other parrots, suggesting an increased binocular overlap in the visual field. The Kakapo exhibits an eye shape that is consistent with other nocturnal birds, including owls and nightjars, but is also within the range of the diurnal parrots. With respect to the brain, the Kakapo has a significantly smaller optic nerve and tectofugal visual pathway. Specifically, the optic tectum, nucleus rotundus and entopallium were significantly reduced in relative size compared to other parrots. There was no apparent reduction to the thalamofugal visual pathway. Finally, the retinal morphology of the Kakapo is similar to that of both diurnal and nocturnal birds, suggesting a retina that is specialised for a crepuscular niche. Overall, this suggests that the Kakapo has enhanced light sensitivity, poor visual acuity and a larger binocular field than other parrots. We conclude that the Kakapo possesses a visual system unlike that of either strictly nocturnal or diurnal birds and therefore does not adhere to the traditional view of the evolution of nocturnality in birds

Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

Background: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. Results: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. Conclusions: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates

Reproductive Effort Of Male And Female Killdeer (charadrius Vociferus) (michigan).

The reproductive investment strategies of the sexes were analyzed for Killdeer (Charadrius vociferus), a monogamous plover. The investments of the sexes in reproductive (mating and parental) effort, were studied during 1983 near Ann Arbor and 1984-1985 at Houghton Lake, Michigan. Investments were measured in terms of time, energy, and risk-taking. Time-energy budgets were used to test the predictions that: (1) males invest more in mating effort (ME) than females; (2) females invest more in parental effort (PE) than males; (3) male and female cumulative energy expenditures in reproductive effort (RE) are equal; and (4) mate removal results in increased investment and lower reproductive success for the 'deserted' parent. Males' cumulative energy expenditures in RE were higher than females' over a successful nesting attempt. However, the early high PE by females, and the timing of nest failures, resulted in females investing more PE than males over the season. Similarly, male investment in ME was higher than female ME investment over the season. Over the breeding season males and females invested the same amount of energy in RE. Males approached predators closer, displayed more intensely, and remained on the nest longer during a predator approach than females. 'Risk-taking' by both sexes increased during incubation, peaked at hatching, and decreased as chicks developed. Responses varied with the predator species, the mode of predator approach, and the distance between the predators and the offspring. 'Deserted' parents were unable to raise offspring alone. However, males were able to hatch chicks, whereas females lost or abandoned their nests a few days after mate removal. Monogamy in killdeer may result from high nest failure rates, low reproductive success of uni-parental care, and the nature of parental care. The effect of nest failure on the relative investments of the sexes has been overlooked in the relationship between parental investment and mating systems.Ph.D.Biological SciencesEcologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127996/2/8712081.pd

Female song rate and structure predict reproductive success in a socially monogamous bird.

Bird song is commonly regarded as a male trait that has evolved through sexual selection. However, recent research has prompted a re-evaluation of this view by demonstrating that female song is an ancestral and phylogenetically widespread trait. Species with female song provide opportunities to study selective pressures and mechanisms specific to females within the wider context of social competition. We investigated the relationship between reproductive success and female song performance in the New Zealand bellbird (Anthornis melanura), a passerine resident year round in New Zealand temperate forests. We monitored breeding behavior and song over three years on Tiritiri Matangi Island. Female bellbirds contributed significantly more towards parental care than males (solely incubating young and provisioning chicks at more than twice the rate of males). Female song rate in the vicinity of the nest was higher than that of males during incubation and chick-rearing stages but similar during early-nesting and post-breeding stages. Using GLMs, we found that female song rates during both incubation and chick-rearing stages strongly predicted the number of fledged chicks. However, male song rate and male and female chick provisioning rates had no effect on fledging success. Two measures of female song complexity (number of syllable types and the number of transitions between different syllable types) were also good predictors of breeding success (GLM on PC scores). In contrast, song duration, the total number of syllables, and the number of ‘stutter’ syllables per song were not correlated with fledging success. It is unclear why male song rate was not associated with reproductive success and we speculate that extra-pair paternity might play a role. While we have previously demonstrated that female bellbird song is important in intrasexual interactions, we clearly demonstrate here that female song predicts reproductive success. These results, with others, highlight the need for a change in how we view the significance of female secondary sexual traits; traits long underestimated due to a focus on male song