Hugh Drummond

National Autonomous University of Mexico | UNAM · Department of Evolutionary Ecology

Parental overproduction is hypothesized to hedge against uncertainty over food availability and stochastic death of offspring and to improve brood fitness. Understanding the evolution of overproduction requires quantifying its benefits to parents across a wide range of ecological conditions, which has rarely been done. Using a multiple hypotheses a...

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average...

The sex of an animal’s siblings can potentially have long-term effects on its development if it competes or cooperates with them in a brood or litter. For the first test of lifelong developmental effects of infant siblings’ sex in a wild animal, we monitored broods of two blue-footed booby (Sula nebouxii) chicks that recruited intact into their nat...

Weather conditions can profoundly affect avian reproduction. It is known that weather conditions prior to and after the onset of reproduction can affect the breeding success of birds. However, little is known about how seasonal weather variability can affect birds' breeding performance, particularly for species with a slow pace of life. Long-term s...

Haemosporidian parasites are common in birds but are seldom reported in seabirds. The absence of vectors or genetic resistance to infection have been proposed to explain this pattern. However, screening of blood parasites in many seabirds has been done only by visual inspection of blood smears, which can miss low-intensity infections, and molecular...

Females and males often exhibit different survival in nature, and it has been hypothesized that sex chromosomes may play a role in driving differential survival rates. For instance, the Y chromosome in mammals and the W chromosome in birds are often degenerated, with reduced numbers of genes, and loss of the Y chromosome in old men is associated wi...

Weather conditions can profoundly affect avian reproduction. Thus far, most studies on weather effects have focused on how weather conditions prior to clutch initiation affect laying dates and, ultimately, breeding success. By contrast, little is known of how weather conditions after the onset of reproduction affect birds. Using a 32-year populatio...

The question of how to program the removal of two invasive mammals, typically cats and rats, from a marine island without increasing risk to native prey species has received two general answers based on ecological theory: removal of cats must be accompanied by control of their mesopredator prey, and risk is minimized by removing both invaders simul...

Haemosporidian parasites are common in birds, but often are not in seabirds. The absence of vectors/genetic resistance to infection have been proposed to explain this pattern. Examination of different host populations is required to confirm the absence of blood parasites in widespread host species, which could be differently exposed to blood parasi...

Assortative mating by telomere lengths has been observed in several bird species, and in some cases may increase fitness of individuals. Here we examined the relationship between telomere lengths of Blue-footed Booby ( Sula nebouxii ) mates, long-lived colonial seabirds with high annual divorce rates. We tested the hypothesis that interactions betw...

In this study, we explored chemosensory, ingestive and prey-catching responses of neonate Mexican Black-bellied Gartersnakes (Thamnophis melanogaster) to crayfish (Cambarellus montezumae). By comparing snakes from a recently discovered crayfish-eating population and a typical non-crayfish-eating population, we asked which behavioral components chan...

Although stressful natal conditions are expected to have developmental impacts that prejudice fitness, wild animals sometimes respond to early-life adversity with phenotypic resilience or make life-history adjustments that apparently mitigate fitness penalties. Whether these adjustments enable long-lived animals to completely evade impacts of na...

The probability of Blue‐footed Booby Sula nebouxii fledglings becoming reproductive adults is maximal when one parent is old and the other young, and minimal when both are old or young. No mechanism has been identified to explain this pattern, but here we showed that nestlings with different‐aged parents are the least infested with ticks. This resu...

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 w...

Reproductive timing in many taxa plays a key role in determining breeding productivity ¹, and is often sensitive to climatic conditions ² . Current climate change may alter the timing of breeding at different rates across trophic levels, potentially resulting in temporal mismatch between the resource requirements of predators and their prey ³ . Thi...

In wild long-lived animals, analysis of impacts of stressful natal conditions on adult performance has rarely embraced the entire age span, and the possibility that costs are expressed late in life has seldom been examined. Using 26 years of data from 8541 fledglings and 1310 adults of the blue-footed booby (Sula nebouxii), a marine bird that can l...

In long-lived species, behaviour is expected to vary across the lifespan, first improving with maturation and experience and then declining with senescence, but measurement is rare, particularly during old age. Measuring nest defence intensity in 255 known-age blue-footed boobies (Sula nebouxii) of 19 age classes confirmed the inverted-U pattern: i...

Morphological convergence is expected when organisms which differ in phenotype experience similar functional demands, which lead to similar associations between resource utilization and performance. To consume prey with hard exoskeletons, snakes require either specialized head morphology, or to deal with them when they are vulnerable , for example,...

In juvenile and adult animals, including mammals, birds, fishes and a crustacean, competition for food becomes increasingly aggressive as its spatial concentration increases. This ecological relationship has not been investigated in infant animals, although it is thought that broods of precocial chicks of some avian species compete aggressively for...

Parasites are a major risk for group-living animals and seabirds are notoriously susceptible to ectoparasite infestations because they commonly nest in dense colonies. Ticks parasitize seabirds across all biogeographical regions and they can be particularly harmful to nestlings, but the ecological factors that affect their transmission to chicks ar...

Variability in population numbers is a central issue in evolutionary ecology and also in biodiversity conservation. However, for most seabirds this information is lacking and tropical populations are virtually unstudied. Long-term studies are warranted because world's seabird populations exhibit an overall declining trend since 1950. Using data spa...

The function of female birds' extra-pair (EP) behavior has remained an unresolved question in ornithology and behavioral ecology for > 30 yr. The genetic compatibility hypothesis (GCH) proposes that females benefit by acquiring biological sires that yield more heterozygous, and therefore fitter, offspring than their social mates. We used ten polymo...

Explaining the remarkable variation in socially monogamous females' extrapair ( EP ) behaviour revealed by decades of molecular paternity testing remains an important challenge. One hypothesis proposes that restrictive environmental conditions (e.g. extreme weather, food scarcity) limit females' resources and increase EP behaviour costs, forcing fe...

The evolution of remating and prolonged pair bonds in animals has generally been explained in terms of improved coordination and cooperation between familiar individuals, but costs of mate familiarity have rarely been considered. A possible cost for males is increased risk of losing paternity if familiarity enables females to detect when alternativ...

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes toward...

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes toward...

When animals potentially occupy diverse microhabitats, how can camouflage be achieved? Here we combine descriptive and experimental methods to uncover a novel form of phenotypic plasticity in the camouflage of bird eggs that may be present in other avian taxa. Soil from the bare substrate adheres to the blue-footed booby’s (Sula nebouxii’s) pale eg...

It is widely expected that the quality of offspring will vary with the age of their parents and that this variation should influence animals' choice of mates. However, theoretical predictions for age effects are contradictory and, to our knowledge, we do not know for any wild animal how the quality of offspring is affected by both parents' ages acr...

Variation in the age at first reproduction may have important implications for growth and dynamics of populations, but these potential impacts remain virtually unexplored. By using 26 years of data from a marked colony of blue-footed boobies Sula nebouxii (Milne-Edwards), we tested whether survival of early recruits is lower in comparison to late r...

An extensive experimental literature documenting negative impacts of early stresses such as food deprivation, elevated corticosterone, and brood enlargement on numerous morphological, physiological, and behavioral traits of adult birds has left the impression of generalized developmental vulnerability to stress in birds. However, descriptive studie...

It is widely expected that the quality of offspring will vary with the age of their parents and that this variation should influence animals’ choice of mates. However, theoretical predictions for age effects are contradictory and, to our knowledge, we do not know for any wild animal how the quality of offspring is affected by both parents’ ages acr...

Females sometimes obtain older sires for their offspring through extra-pair interactions, but how female age influences paternity is largely unexplored and interactive effects across the age span of both sexes have not been analyzed. To test whether female choice of sire age varies with female age in the blue-footed booby (Sula nebouxii), we examin...

Individual variation in sexual fidelity and extrapair paternity (EPP) is widely attributed to environmental heterogeneity, but the only variables known to be influential are food abundance and density of conspecific breeders (potential extrapair partners). Habitat structure is thought to impact EPP but is rarely measured and, when considered, is us...

The good genes hypothesis has long been a major focus of research on the function of extrapair (EP) behaviour by socially monogamous females. It predicts that females should be less faithful when paired to low-quality males and, as EP males become increasingly superior to their social mates, that EP males should be of higher quality than the males...

Prolonged pair bonds have the potential to improve reproductive performance of socially monogamous animals by increasing pair familiarity and enhancing coordination and cooperation between pair members. However, this has proved very difficult to test robustly because of important confounds such as age and reproductive experience. Here, we address l...

Food shortage and other challenges associated with El Niño Southern Oscillation (ENSO) experienced early in life may have long-term impacts on life history traits, but these potential impacts remain virtually unexplored. By monitoring 2556 blue-footed boobies from 11 cohorts, we showed that birds facing warm water ENSO conditions (and probably low...

Experiments on birds, fish and mammals have shown that adverse conditions during infancy can produce diverse long‐term and delayed deficits during adulthood, prejudicing both the individual and its offspring. Natural selection should prepare animals to cope with adversity of the type, magnitude and timing that commonly occur in their natural habita...

Meraz, J., Ancona, S., Rodríguez, C., and Drummond, H. 2013. Reproduction of the blue-footed booby predicts commercial fish abundance in the eastern tropical Pacific. – ICES Journal of Marine Science, 70: 1263–1272. To establish whether reproduction in a colony of the blue-footed booby in the eastern tropical Pacific predicts local abundance of pre...

The behaviour that mediates divorce and partner change in socially monogamous species is largely unstudied and unknown, although roles and adaptive functions in some birds have been inferred from breeding outcomes, partial behavioural records and captive studies. Here, roles and func- tions of natural within-season mate switching of a colonial bird...

We describe the diet of Thamnophis melanogaster on the Mexican plateau, including geographic variation between populations in the Lerma and Tula drainages (represented by 39 localities), annual and seasonal variation in an isolated population in the Nazas drainage, and sexual and size-related variation in all three drainages. The Mexican Black-bell...

As stresses in early development may generate costs in adult life, sibling competition and conflict in infancy are expected to diminish the reproductive value of surviving low-status members of broods and litters. We analysed delayed costs to blue-footed booby fledglings, Sula nebouxii, of junior status in the brood, which involves aggressive subor...

Reductions in the availability of energetically valuable prey associated with the El Nino Southern Oscillation (ENSO) may force seabirds to switch to low-energy prey or smaller prey, with consequent effects on their fitness. Impacts of ENSO on seabird diet have been documented in several regions but remain unexplored in the warm eastern tropical Pa...

Recent studies of wild populations provide compelling evidence that survival and reproduction decrease with age because of senescence, a decline in functional capacities at old ages. However, in the wild, little is known about effects of parental senescence on offspring quality. We used data from a 21-year study to examine the role of parental age...

Despite frequent suggestions that dominance-subordination relationships in infancy can affect subsequent agonistic potential during adult life, to our knowledge no explicit test has been made. Experiments have shown that adverse conditions during early development can have long-term effects on a variety of traits ranging from growth to competitive...

Poor nutrition and other challenges during infancy can impose delayed costs, and it has been proposed that expression of costs during adulthood should involve increased mortality rather than reduced reproduction. Demonstrations of delayed costs come mostly from experimental manipulations of the diet and hormones of captive infants of short-lived sp...

A survey of the helminth fauna of the blue-footed booby, Sula nebouxii, on Isla Isabel, off the Pacific coast of México, is presented. Eight parasite species were found: 4 digeneans (Galactosomum puffini , Mesostephanus microbursa, Opisthometra planicollis, and Renicola thapari), 3 nematodes (Contracaecum sp., Porrocaecum sp., and Tetrameres sp.),...

As organisms age, DNA of somatic cells deteriorates, but it is believed that germ cells are protected from DNA-damaging agents. In recent years, this vision has been challenged by studies on humans indicating that genomic instability in germ cells increases with age. However, nothing is known about germ line senescence in wild animals. Here, we exa...

1. There is increasing interest in the impacts of El Niño Southern Oscillation (ENSO) on reproduction of apical predators such as seabirds and marine mammals. Long-term studies documenting ENSO effects on reproduction of seabirds in the warm tropics are scarce, and differential sensitivity of breeding parameters to ENSO has rarely been explored. 2....

Theories of ageing predict that early reproduction should be associated with accelerated reproductive senescence and reduced longevity. Here, the influence of age of first reproduction on reproductive senescence and lifespan, and consequences for lifetime reproductive success (LRS), were examined using longitudinal reproductive records of male and...

After training as a lawyer in England, Hugh Drummond switched to English language teaching so that he could travel the world. While training teachers in Mexico, he discovered the magic of Ethology, studied it privately for a while, and then did a doctorate in Experimental Psychology and Ethology at the University of Tennessee. Hugh studied the beha...

Studies of laboratory organisms have suggested that parental age affects the genetic variance of offspring traits. This effect can engender age-specific variance in genetic contributions to evolutionary change in heritable traits under directional selection, particularly in age-structured populations. Using long-term population data of the blue-foo...

Observations were made on the feeding behavior of 8 newborn Macroclemys temminckii, a species known to lure fish prey with a vermiform appendage situated on the floor of the oral cavity. Each turtle was observed on 3 occasions, including its first feeding experience, over a 7-week period. 4 phases of predation on live fish are described: waiting, l...

Many garter snakes, Thamnophis melanogaster, at a desert pond first started foraging for tadpoles when mean water surface temperature was about 20 °C (at 0945–1015 h), and the number of snakes tripled when water temperature reached about 24 °C (at 1100–1130 h). In two years, snakes foraged in April and May, but not in March when water never reached...

In marine ecosystems climatic fluctuation and other physical variables greatly influence population dynamics, but differential effects of physical variables on the demographic parameters of the two sexes and different age classes are largely unexplored. We analyzed the effects of climate on the survival and recruitment of both sexes and several age...

In multitudinous breeding colonies, kin interactions could go unnoticed because we are unaware of the kinship among adults we observe. Evidence of cooperation and competition between close adult kin in a blue-footed booby colony was sought by analyzing patterns of natal dispersal and proximity of nests. Male and female recruits nested closer to the...

Senescence could depress prenatal and postnatal capacities of mothers to invest in offspring. Longitudinal observations on the blue-footed booby (Sula nebouxii) revealed a quadratic effect of female age on fledgling production and cohort differences in rate of reproductive decline. By swapping clutches between females of different ages, we tested w...

Simultaneous effects of mate guarding on a male's energy intake and expenditure have not been measured. We tested whether guarding males of the western Mexican whiptail lizard, Aspidoscelis costata, reduce energy intake and increase expenditure of energy on male–male aggression. Also, we tested whether guarding males calibrate their aggressive beha...

In the blue-footed booby (Sula nebouxii), the first-hatched chick aggressively dominates its sibling and sometimes kills it when food is in short supply. To investigate the endocrine correlates of dominance-subordinance and hunger-induced agonism, we deprived 15-20-d-old single-chick and two-chick broods of food during 48 h by taping chicks' necks...

Somatic deterioration in ageing animals may arise from allocation of resources to reproduction at the expense of repair and maintenance. Thus, accumulated reproductive effort is likely to progressively limit the expression of sexual ornaments at older ages. We analysed the effect of age and reproductive effort on the sexual attractiveness (foot col...

Blue-footed boobies (Sula nebouxii) are socially monogamous, colonial seabirds exhibiting intra-specific nest parasitism and extra-pair copulations. Prior DNA fingerprinting assays failed to detect extra-pair offspring in the nests of congeners, and the rate of intra-specific nest parasitism has not been estimated using molecular techniques. We des...

The relationships between breeding site location in forest habitat and age, behaviour and reproductive performance of Blue-footed Boobies Sula nebouxii were examined in two different plots on the northeast corner of Isla Isabel, Mexico. Birds nesting closer to the forest edge, where nest density is highest, laid their clutches earlier and fledged m...

In some vertebrate species, parents create a large brood or litter then, in the event of unfavourable ecological conditions, apparently allow the number of offspring to be adaptively reduced through siblicide. But how is sibling aggression regulated so that deaths occur only in unfavourable conditions? One proposed mechanism is brood size-dependent...

When the costs of rearing males and females differ progeny sex ratios are expected to be biased toward the less expensive sex. Blue-footed booby (Sula nebouxii) females are larger and roughly 32% heavier than males, thus presumably more costly to rear. We recorded hatching and fledging sex ratios in 1989, and fledging sex ratios during the next 5 y...

Contradictory patterns of density-dependent animal dispersal can potentially be reconciled by integrating the conspecific attraction hypothesis with the traditional competition hypothesis. We propose a hypothesis that predicts a U-shaped relationship between density and both natal and breeding dispersal distance. Using 10 years of observations on a...

El patrón temporal de actividad sexual de machos y hembras es un aspecto crucial de los sistemas de apareamiento. Analizamos si la reproducción de la lagartija rayada, Aspidoscelis costata, de una isla tropical del Pacífico mexicano es estacional o continua y si está relacionada con algunos factores meteorológicos. Análisis macro y microscópicos de...

We examined androgens in clutches of two booby species that differ in their sibling conflict. Blue-footed booby Sula nebouxii chicks show an aggression-submission relationship, aggression is normally moderate and siblicide is facultative. Brown booby Sula leucogaster chicks show an aggression-aggression relationship, aggression of both chicks can b...

Theoreticians propose that trained winning and losing are important processes in creating linear animal dominance hierarchies, and experiments have shown that both processes can occur in animals, but their actual roles in creating natural hierarchies are unknown. We described agonism in 18 broods of three blue-footed boobies, Sula nebouxii, a speci...

Squabbles and squawks are a common feature of avian family life, so it is no wonder that birds are model species for the study of parent–offspring conflict. But how much do these behaviours really tell us about the evolutionary conflicts of interest between parents and their young? Here, we provide a brief review that is aimed primarily at ornithol...

Post-copulatory female accompaniment by males is often interpreted as mate guarding. However, several alternative hypotheses for the function of accompaniment have received little attention. We analysed potential functions of post-copulatory accompaniment in whiptail lizards, Aspidoscelis costata, by comparing 23 accompanied females and 54 unaccomp...

We tested the hypothesis that stability of a linear dominance hierarchy is due to each individual being trained to a different level of general aggressiveness. This mechanism, combined with assessment of aggressiveness, is particularly likely when individual recognition is absent, as may be the case in young broods of altricial chicks. Dominance re...

In many parentally fed species, siblings compete for food not only by begging and scrambling, but also by violently attacking each other. This aggressive competition has mostly been studied in birds, where it is often combined with dominance subordination, aggressive intimidation, and siblicide. Previous experimental and theoretical studies propose...

Philopatry over the lifetime and its relationship with reproductive success were examined using longitudinal records of nest location and reproduction of individual blue-footed boobies. Males showed shorter natal dispersal than females, and natal dispersal distance of both sexes were unrelated to either first reproductive success or lifetime reprod...

1. Understanding the effects of individual and population factors on variation in breeding dispersal (the movement of individuals between successive breeding sites) is key to identifying the strategies behind breeders' movements. Dispersal is often influenced by multiple factors and these can be confounded with each other. We used 13 years of data...