Publications

hormonal correlates of siblicide in galápagos nazca boobies.	nazca boobies (sula granti) show unconditional obligate siblicide immediately after hatching, reducing the typical two-egg clutch size to one. we studied body mass changes and levels of testosterone (t), corticosterone (cort), and progesterone (p) for a-chicks (dominant, first hatched), b-chicks (subordinate, second hatched), and singletons, during the first 7 days after hatching, when siblicide normally occurs. mass increase with age was higher for a-chicks than for singletons and b-chicks. thi ...	2001	11467880
correlation between plasma steroids and chick visits by nonbreeding adult nazca boobies.	nonbreeding adult nazca boobies (sula granti) often approach unattended chicks and perform parental and/or aggressive behaviors toward the chicks. earlier descriptions of these encounters included sexual behaviors as well. we studied hormonal correlates of chick visits by such nonbreeding boobies during the breeding season. we compared the hormonal status of chick-visiting adults with that of nonvisiting adults in the colony. we determined levels of corticosterone (cort), testosterone (t), andro ...	2003	12695114
actuarial and reproductive senescence in a long-lived seabird: preliminary evidence.	the evolutionary theory of aging predicts that pelagic seabirds, which have low extrinsic mortality, should show exceptional longevity. these taxa appear to show the lowest rates of actuarial senescence among birds yet display declining reproductive performance at advanced ages. we have studied survival and reproduction of nazca boobies (sula granti) in the remote galápagos islands since 1984. we found a slight but detectable increase in mortality rate in the oldest (> or =19 yrs) cohort, indica ...	2003	12855283
foot-mediated incubation: nazca booby (sula granti) feet as surrogate brood patches.	incubation in most avian species involves transferring heat from parent to egg through a highly vascularized brood patch. some birds, however, do not develop a brood patch. unusual among birds, these species hold their eggs under the webs of their feet, but the role of the feet in heat transfer is uncertain. often the webs are positioned between the feathered abdomen and the egg during incubation, suggesting that either the abdomen, the feet, or both could transfer heat to the egg. we studied he ...	2008	12905122
diel changes in plasma melatonin and corticosterone concentrations in tropical nazca boobies (sula granti) in relation to moon phase and age.	we investigated the effects of moon phases and age on diel rhythms of plasma melatonin and corticosterone in free-living nazca boobies (sula granti) on the galápagos islands, ecuador. melatonin and corticosterone secretion are regulated by the circadian system and the two hormones play a role in the control of locomotor activity and foraging, which can be influenced by moon phases. these seabirds have a long life span and in many vertebrates circadian function deteriorates with age. the function ...	2003	12957473
contributions of marginal offspring to reproductive success of nazca booby (sula granti) parents: tests of multiple hypotheses.	while obligate siblicide is a phylogenetically widespread behavior, known from plants, insects, birds, and other taxa, with important implications for life history evolution, comprehensive evaluations of its costs and benefits to parents are rare. we used 12 years of breeding and band resight data to evaluate the importance of several potential benefits that marginal offspring (the usual victims of obligate siblicide) could provide to parent nazca boobies (sula granti), a seabird. we found no ev ...	2006	16208491
serial monogamy and sex ratio bias in nazca boobies.	biased operational sex ratios (osrs) can drive sexual selection on members of the over-represented sex via competition for mates, causing higher variance and skew in reproductive success (rs) among them if an individual's quality is a persistent characteristic. alternatively, costs of reproduction may degrade breeding performance, creating the opportunity for members of the limiting sex to switch mates adaptively, effectively homogenizing variance and skew in rs among the sex in excess. we teste ...	2007	17567557
the genetic basis of the plumage polymorphism in red-footed boobies (sula sula): a melanocortin-1 receptor (mc1r) analysis.	the red-footed booby (sula sula) is considered one of the most polymorphic seabirds, with 3 recognized major adult plumage types: 1) white, 2) white-tailed brown, and 3) brown and several degrees of intermediates. here we show that the white/melanic polymorphism observed in this species is perfectly associated with 2 point substitutions, val85met and his207arg, at the melanocortin-1 receptor (mc1r) gene. among the melanic plumage variants, we also found a strong association between the degree of ...	2007	17602182
assessment of costs of reproduction in a pelagic seabird using multistate mark-recapture models.	we used a long-term population band-resight survey database, a parallel reproduction database, and multistate mark-recapture analysis to assess the costs of reproduction, a keystone concept of life-history evolution, in nazca boobies (sula granti) from punta cevallos, isla española, galápagos, ecuador. we used eight years of resight and breeding data to compare models that included sex- and state-specific survival probabilities and probabilities of transition between reproductive states using mu ...	2007	17683437
perinatal androgens and adult behavior vary with nestling social system in siblicidal boobies.	exposure to androgens early in development, while activating adaptive aggressive behavior, may also exert long-lasting effects on non-target components of phenotype. here we compare these organizational effects of perinatal androgens in closely related nazca (sula granti) and blue-footed (s. nebouxii) boobies that differ in neonatal social system. the older of two nazca booby hatchlings unconditionally attacks and ejects the younger from the nest within days of hatching, while blue-footed booby ...	2008	18560542
hormonal effects of maltreatment in nazca booby nestlings: implications for the "cycle of violence".	non-breeding nazca booby adults exhibit an unusual and intense social attraction to non-familial conspecific nestlings. non-parental adult visitors (navs) seek out and approach unguarded nestlings during daylight hours and display parental, aggressive, and/or sexual behavior. in a striking parallel to the "cycle of violence" of human biology, degree of victimization as a nestling is strongly correlated with frequency of future maltreatment behavior exhibited as an adult. here, we investigate can ...	2011	21439288
philopatry drives genetic differentiation in an island archipelago: comparative population genetics of galapagos nazca boobies (sula granti) and great frigatebirds (fregata minor).	seabirds are considered highly mobile, able to fly great distances with few apparent barriers to dispersal. however, it is often the case that seabird populations exhibit strong population genetic structure despite their potential vagility. here we show that galapagos nazca booby (sula granti) populations are substantially differentiated, even within the small geographic scale of this archipelago. on the other hand, galapagos great frigatebird (fregata minor) populations do not show any genetic ...	2012	23170212
comparative host-parasite population genetic structures: obligate fly ectoparasites on galapagos seabirds.	parasites often have shorter generation times and, in some cases, faster mutation rates than their hosts, which can lead to greater population differentiation in the parasite relative to the host. here we present a population genetic study of two ectoparasitic flies, olfersia spinifera and olfersia aenescens compared with their respective bird hosts, great frigatebirds (fregata minor) and nazca boobies (sula granti). olfersia spinifera is the vector of a haemosporidian parasite, haemoproteus iwa ...	2013	23659306
comparative ectoparasite loads of five seabird species in the galapagos islands.	in this paper we describe the ectoparasitic lice (insecta: phthiraptera) found on 5 species of seabirds (magnificent frigatebird fregata magnificens; great frigatebird fregata minor ; nazca booby sula granti ; blue-footed booby sula nebouxii ; and red-footed booby sula sula ) on the galapagos archipelago. we found 9 species of ectoparasitic lice: 5 species of pectinopygus ischnocerans, 1 infesting each host; 2 species of colpocephalum amblyceran lice, 1 on each frigatebird species; and 2 shared ...	2014	24911632
corticosterone stress response shows long-term repeatability and links to personality in free-living nazca boobies.	the concept of "coping styles", or consistently different responses to stressors, is of broad interest in behavioral ecology and biomedicine. two critical predictions of this concept are individual consistency of neurophysiological and behavioral responses (relative to population variability) and a negative relationship between aggression/proactivity and hypothalamic-pituitary-adrenal axis reactivity. recent studies failed to provide strong support for these predictions, especially outside of st ...	2014	25220912
yawning, acute stressors, and arousal reduction in nazca booby adults and nestlings.	yawning is a familiar and phylogenetically widespread phenomenon, but no consensus exists regarding its functional significance. we tested the hypothesis that yawning communicates to others a transition from a state of physiological and/or psychological arousal (for example, due to action of a stressor) to a more relaxed state. this arousal reduction hypothesis predicts little yawning during arousal and more yawning (above baseline) during and after down-regulation of arousal. experimental captu ...	2015	25498600
lineage sorting in multihost parasites: eidmanniella albescens and fregatiella aurifasciata on seabirds from the galapagos islands.	parasites comprise a significant percentage of the biodiversity of the planet and are useful systems to test evolutionary and ecological hypotheses. in this study, we analyze the effect of host species identity and the immediate local species assemblage within mixed species colonies of nesting seabirds on patterns of genetic clustering within two species of multihost ectoparasitic lice. we use three genetic markers (one mitochondrial, coi, and two nuclear, ef1-α and wingless) and maximum likelih ...	2015	26380662
commentary: yawning, acute stressors, and arousal reduction in nazca booby adults and nestlings.		2015	26579037
nesting distributions of galápagos boobies (aves: sulidae): an apparent case of amensalism.	blue-footed boobies (sula nebouxii) in the galápagos islands nest at coastal sites such as cliff edges if nazca boobies (s. granti) are absent. however, if sympatric with nesting nazca boobies, they nest nearby, but farther inland, in areas with little topographical relief. nazca boobies nest at the coastal sites whether blue-footed boobies are present or not. the segregated nesting pattern of these two species offers a model system to investigate factors influencing community structure. we test ...	2002	28547420
serum chemistry of free-ranging nazca boobies ( sula granti).	this study reports body mass and serum chemistry reference values of 121 male and 57 female nazca boobies (sulidae: sula granti) from a colony on isla española, galápagos islands, ecuador. circulating aspartate aminotransferase, creatine kinase, lactate dehydrogenase, total protein, immunoglobulin y, uric acid, blood urea nitrogen, triglycerides, cholesterol, and creatinine were quantified and analyzed by sex. sex explained little variance in all examined variables except mass; females were heav ...	2017	29297819
early-life maltreatment predicts adult stress response in a long-lived wild bird.	persistent phenotypic changes due to early-life stressors are widely acknowledged, but their relevance for wild, free-living animals is poorly understood. we evaluated effects of two natural stressors experienced when young (maltreatment by adults and nutritional stress) on stress physiology in wild nazca boobies (sula granti) 6-8 years later, an exceptionally long interval for such studies. maltreatment as a nestling, but not nutritional stress, was associated years later with depressed baselin ...	2018	29321248
pacific decadal and el niño oscillations shape survival of a seabird.	understanding and modeling population change is urgently needed to predict effects of climate change on biodiversity. high trophic-level organisms are influenced by fluctuations of prey quality and abundance, which themselves may depend on climate oscillations. modeling effects of such fluctuations is challenging because prey populations may vary with multiple climate oscillations occurring at different time scales. the analysis of a 28-yr time series of capture-recapture data of a tropical seab ...	2018	29714830
sex-specific patterns of senescence in nazca boobies linked to mating system.	under life-history theories of ageing, increased senescence should follow relatively high reproductive effort. this expectation has rarely been tested against senescence varying between and within the two sexes, although such an approach may clarify the origins of sex-specific ageing in the context of a given mating system. nazca boobies (sula granti; a seabird) practise serial monogamy and biparental care. a male-biased population sex ratio results in earlier and more frequent breeding by femal ...	2019	30746683
senescence in nature: new insights from a long-term seabird study.	in focus: tompkins, e. m., & anderson, d. j. (2019). sex-specific patterns of senescencein nazca boobies linked to mating system. journal of animal ecology, 88, 986-1000. https://doi.org/10.1111/1365-2656.12944. sex-specific differences in senescence and environmental impacts on senescence in both sexes remain poorly understood. tompkins and anderson (2019) studied senescence in survival (hereafter called actuarial senescence) and in reproduction (hereafter called reproductive senescence) in naz ...	2019	31274204