Microhabitats for Oviposition and Male Clutch Attendance in Hyalinobatrachium aureoguttatum (Anura: Centrolenidae)

We collected 354 blood samples from territorial and nonterritorial male Redwinged Blackbirds (Agelaius phoeniceus) to determine plasma levels of testosterone (T) and corticosterone (B) of a polygynously breeding bird, and to determine the potential influences of steroid hormone levels on obtaining breeding territories. In contrast to monogamous species, we found no peak in average T levels early in the breeding season and a five-weeklong high plateau in T levels during the period when most nests were initiated. These endocrinologic characteristics may result from the long breeding season and resource defense polygyny of Red-wings. Territory owners had higher T levels during the breeding season than adult floaters. Subadult floaters had the lowest levels. Also, territory owners generally had the highest circulating levels of corticosterone during most of the breeding season. This implies greater energetic demands and stress on owners than on floaters. During early April the T levels of males for which we had complete breeding and territorial history information correlated significantly with their annual fledging success, and males with more breeding experience tended to have higher peak T levels. There was also a positive correlation between B levels in early April and eventual fledging success. Circulating levels of steroid hormones may affect territory ownership and reproductive success in this species.

The relationship of hormones to the reproductive behaviour of birds, referring especially to parental behaviour: A review

Southern hairy-nosed wombats (SHNW; Lasiorhinus latifrons) rarely breed successfully in captivity, which has been primarily associated with a dearth of knowledge concerning their reproductive physiology and behaviour. One approach to better understanding those parameters that might influence captive wombat husbandry and management is the application of non-invasive techniques that facilitate evaluation of reproductive and adrenal hormones. Non-invasive urine samples are ideal for the assessment of both reproductive capacity and adrenal function in captive wildlife species but robust biological validation is initially required to confirm the reliability of this information. Once validated, animal behaviour can then be mapped in parallel with urinary hormone metabolites, and data from spermatorrhoea, to more precisely determine the success or otherwise of husbandry practices focused on reproductive success. This thesis examined the efficacy of using urinary testosterone and cortisol in the captive male SHNWs as means of understanding changes in hormone concentrations with respect to reproductive and adrenal function, breeding behaviour and social structure. Enzyme immunoassays (EIAs) were evaluated and validated for their potential to measure biologically relevant changes in plasma and urinary luteinizing hormone (LH), testosterone metabolites (UTM) and cortisol metabolites (UCM) in captive SHNWs. GnRH agonist and ACTH agonist challenges were conducted to validate urinary testosterone (male wombat only) and cortisol (male and female wombats) EIAs, respectively. Following intra-muscular injection of 8 - 12 g buserelin (n = 4 males) there was a significant increase in both plasma (P < 0.001) and urinary testosterone concentration (P < 0.001) 60 min and 21 h after administration, respectively. Plasma LH levels were elevated (P < 0.05) at 20 min but there was no significant increase found in urinary LH concentrations after injection. Intra-muscular injection of Synacthen® Depot (250 g) (n = 3 males, 3 females) resulted in a significant increase (P < 0.05) in plasma cortisol secretion after 15 min and in urinary cortisol concentrations 3 h post injection. Sex related differences in cortisol secretion were also reported in this study. These findings suggest that while urinary LH might not be an appropriate index for evaluating the reproductive status in captive male SHNW, UTM and UCM enzyme-immunoassays appear to be suitable for the assessment of captive southern hairy-nosed wombat testicular steroidogenic capacity and adrenocortical activity, respectively. Seasonal variation in physiology and social dynamics of a captive male population of SHNW (n = 6) were then evaluated using the validated assays. Seasonal changes in urinary testosterone metabolites (UTM), urinary cortisol metabolites (UCM), qualitative estimates of spermatorrhoea (QS), aggressive behaviour and reproductive behaviour were measured over an 11-month period. While there was no effect of month on QS (GLM ANOVA, P = 0.27), reproductive behaviour (GLM ANOVA, P = 0.19) or aggressive behaviour (Tukey pairwise comparisons), the secretion of UTM (GLM ANOVA, P = 0.051) was only marginally affected by season, compared to that reported for wild male southern hairy-nosed wombats. Mean UCM concentrations of July (0.927 ± 0.0729 ng/mg Cr) and August (0.941 ± 0.0876 ng/mg Cr) 2016 were significantly higher (Tukey pairwise comparisons) than those between October 2015 and January 2016 (October: 0.549 ± 0.0743 ng/mg Cr; November: 0.528 ± 0.0729 ng/mg Cr; December: 0.535 ± 0.0526 ng/mg Cr; January: 0.608 ± 0.0435 ng/mg Cr). To examine the physiology of a perturbation to social dynamics, two trials involving changes in animal location to different enclosure systems were implemented and behavioural data examined for each trial over a six week period; UTM, UCM and general behaviours (n = 27) were measured for each trial. Neither UTM nor UCM concentration varied significantly (P ≥ 0.45) before and after the relocation of wombats. “Scratching” decreased at the group level following the animal exchange in both trials, suggesting that this reduction in self-grooming may be a behavioural response to novel stimuli. UCM and UTM concentrations were both positively correlated with “standing still” and “body rub” behaviours which may reflect some form of hormonal control over what might be regarded as a “freezing response” to external stimuli in this species and marking behaviour, respectively. There was no evidence that changing the social dynamics affected reproductive or agonistic behaviour or hormone concentrations. It is concluded, therefore that captive male SHNWs show reduced seasonality compared to their wild conspecifics, and that while animal relocation created evidence of behavioural responses to novel stimuli, it was not sufficient to affect testosterone or cortisol secretion, within the context of my study.

Most birds incubate their eggs to allow embryo development. This behaviour limits the ability of adults to perform other activities. Hence, incubating adults trade off incubation and nest protection with foraging to meet their own needs. Parents can either cooperate to sustain this tradeoff or incubate alone. The main cause of reproductive failure at this reproductive stage is predation and adults reduce this risk by keeping the nest location secret. Arctic sandpipers are interesting biological models to investigate parental care evolution as they may use several parental care strategies. The three main incubation strategies include both parents sharing incubation duties (‘biparental’), one parent incubating alone (‘uniparental’), or a flexible strategy with both uniparental and biparental incubation within a population (‘mixed’). By monitoring the incubation behaviour in 714 nests of seven sandpiper species across 12 arctic sites, we studied the relationship between incubation strategy and nest predation. First, we described how the frequency of incubation recesses (NR), their mean duration (MDR), and the daily total duration of recesses (TDR) vary among strategies. Then, we examined how the relationship between the daily predation rate and these components of incubation behaviour varies across strategies using two complementary survival analysis. For uniparental and biparental species, the daily predation rate increased with the daily total duration of recesses and with the mean duration of recesses. In contrast, daily predation rate increased with the daily number of recesses for biparental species only. These patterns may be attributed to two independent mechanisms: cryptic incubating adults are more difficult to locate than unattended nests and adults departing the nest or feeding close to the nest can draw predators’ attention. Our results demonstrate that incubation behaviour as mediated by incubation strategy has important consequences for sandpipers’ reproductive success.

Free-living male song sparrows experience three annually repeating life history stages associated with differential expression of sex steroid-dependent reproductive and aggressive behavior. In the breeding stage, they display reproductive and aggressive behavior and have elevated circulating testosterone levels. During molt, males show little or no aggression and no reproductive behavior, and have basal levels of circulating testosterone. In the non-breeding stage, they display high levels of aggression and no reproductive behavior, and have basal levels of circulating testosterone. In order to understand more fully the neural regulation of seasonal aggressive and reproductive behavior, birds were collected during all three life history stages, and levels of neural aromatase, androgen receptor (AR), and estrogen receptor alpha (ERalpha) and beta (ERbeta) mRNA expression were measured. Breeding males had the highest levels of aromatase expression in both the preoptic area (POA) and medial preoptic area/medial bed nucleus of the stria terminalis (mPOA/BSTm), and the highest AR expression levels in the POA, consistent with the well-established role these regions play in the regulation of male reproductive behavior. Aromatase expression in the ventromedial nucleus of the hypothalamus (VMH) was higher during breeding and non-breeding compared with molt, suggesting that the VMH may play a role in the estrogen-dependent regulation of aggression in this species. AR expression also varied in medial HVC and pvMSt, a newly described periventricular region in the medial striatum. ERalpha and ERbeta mRNA expression did not vary seasonally in any brain region examined, suggesting that estrogen-dependent changes in behavior are mediated by differences in neural estrogen synthesis.

A decade of sexual selection studies reveals patterns and processes of fitness variation in male collared lizards

Castration affects reproductive but not aggressive behavior in a cichlid fish

Broodiness is a nuisance and sometimes a serious problem in some poultry. The behaviour is recognized as persistent nesting, usually associated with cessation of egg laying. Broodiness has two components: incubation and brooding behaviour; the former can only be induced in laying hens, while the latter can be induced in both laying and non-laying hens and in males, by forced fostering of chicks. The motivation to incubate wanes after 4-5 weeks sitting on infertile eggs, while brooding behaviour gradually declines as the chicks become independent and egg laying resumes. Incubation and brooding behaviour are associated with low concentrations of plasma luteinizing hormone (LH) and ovarian steroids, and with high and low concentrations of plasma prolactin, respectively. The preoptic area of the hypothalamus (POA) forms part of the neural circuitry controlling both incubation and brooding behaviours. High concentrations of prolactin and low concentrations of plasma LH in incubating hens are a consequence, respectively, of increased vasoactive intestinal polypeptide (VIP) and decreased gonadotrophin-releasing hormone (GnRH) release from the hypothalamus. Changes in the release of these two neuropeptides from the hypothalamus are, in part, a consequence of changes in their rates of synthesis. The release of VIP in incubating hens is stimulated by dopaminergic input from the POA, which in turn is stimulated by a serotonergic input. Incubation behaviour is a form of extended nesting behaviour induced by the synergistic action of oestrogen and progesterone. It is transformed into incubation behaviour by increased prolactin secretion stimulated by neural information transmitted through the brood patch from a clutch of eggs to hypothalamic VIP neurones. Broody control is best achieved by good husbandry directed to discouraging the behaviour. Pharmacological and immunological methods can be used to control or prevent broodiness but for most practical purposes are uneconomic and some may delay resumption of egg production. Broodiness is a polygenic trait, and quantitative trait loci analysis can be applied to identify regions of the genome controlling broodiness. Identification of markers in, or linked to, these genes and associated with broody behaviour is likely to be of value in breeding programmes incorporating DNA marker-assisted selection.

Discrimination between hetero- and conspecifics is the elementary choice an individual performs when searching for potential mates. The level of selectivity and strength of species discrimination is modified by variance in the quality of females, level of the male’s reproductive investment, mate search costs, and the competitive environment. The effect of the competitive environment on both species discrimination and conspecific mate choice has seldom been studied simultaneously. We experimentally manipulated territorial competition ofCalopteryx splendensdamselfly males in the wild, and asked two questions. First, does increased competition influence the territorial males’ responses towards introduced heterospecificC. virgofemales. The effect of the size of the territorial males’ sexual ornaments (wing spot) on their responses towards females was also investigated. Second, does increased competition influence the territorial males’ response towards conspecific females? The effect of the size of the territorial males ornament was again investigated. The mean level of response towards heterospecific females did not change between the control (i.e., no competitors presented) and the competition (i.e., two competitors presented) treatments, but the variance of responses towards heterospecifics was greater in the competition treatment. The territorial males’ responses towards conspecific females did not change between control and competition treatments. These results indicate individual differences in the behavior of males towards heterospecifics when territorial competition was experienced. The observed pattern of discrimination might be adaptive when overall reproductive success is considered.

Reproductive experience can impact how individuals allocate time and energy to reproduction and generate differences in reproductive behavior that leads to experience dependent variation in reproductive success. In order to understand if individual variation in parental behavior is related to environmental temperature and breeding experience, we observed the timing and duration of the first morning off bout in a wild, open cup nesting passerine bird during the incubation and early nestling period. We compared incubation behaviors and nest temperature of inexperienced (second year = first breeding season) and experienced (after second year) female hooded warblers Setophaga citrina . Females left the nest earlier on colder mornings suggesting an energetic constraint due to the long overnight on bout during colder temperatures. During incubation, females increased the duration of the first morning off bout with increasing temperature. Similarly, during the early nestling period, experienced females had shorter off bout duration on colder mornings and increased duration with warmer temperatures. In contrast, inexperienced females increased off bout duration with colder morning temperatures. Experienced females maintained higher nest temperatures and higher minimum nest temperatures compared to inexperienced females. We also found evidence that experienced females nested in microhabitats with higher minimum morning temperature which may buffer older females from colder daily extremes and enable older females to maintain higher nest temperatures. While we found no relationship between incubation and brooding behaviors and fledging success, the proportion of the clutch that hatched was positively related to minimum nest temperature. The ability of experienced females to maintain higher minimum nest temperatures and to adjust brooding behaviors during colder mornings is a potential mechanism that has consequences for nestling condition in a wild population. Our results highlight the need to examine experience‐related parental care behaviors in responding to environmental variation.

In many species, both males and females possess sexual signals, but most research focuses on understanding signal expression in males. Females are often assumed to possess signals as a non-functional by-product of selection on males, but increasing evidence demonstrates functional explanations for variation in female signals. Theory suggests that—for many bird species—differences in long-term fitness associated with female signaling are more likely to be driven by variation in offspring quality than quantity, but research paradigms developed for studying male signals have primarily focused on counting offspring produced. Here, we tested the hypothesis that female ornamentation reliably signals the ability to incubate effectively. We used temperature loggers placed in the nest of common yellowthroat warblers (Geothlypis trichas) to record incubation behavior across multiple breeding attempts. Incubation bout length and the onset of daily activity were highly variable between females, but repeatable within females across multiple nesting attempts. Females with longer bouts and later onset of activity had higher hatching success. Wing length and plumage coloration were not related to incubation length or onset of activity, but were correlated with the total percentage of time spent on the nest each day. However, there was only a trend for repeatability in percentage of time spent on the nest and this measure was not correlated with any metrics of offspring quality or hatching success that we recorded. Therefore, we did not find any single aspect of incubation behavior that was (i) consistent, (ii) related to nestling quality or success, and (iii) signaled by ornamentation. Our results demonstrate the importance of variation in incubation behavior, but also suggest that ornaments are of limited utility as a signal of incubation ability in this species. Nevertheless, our study highlights the need to explore alternative fitness proxies in order to understand variation in female ornamentation. Choosing a high-quality mate is an important determinant of reproductive success and animals often attend to elaborate ornaments as signals of quality during mate choice. In many species, both males and females have ornaments, but most research has focused on male signals and female mate choice. We found that female incubation behavior is associated with both plumage ornaments and hatching success, but there was no single signal that provided reliable information about the aspects of incubation behavior that were related to reproductive success. Our findings suggest that understanding female ornamentation may depend on considering the specific ways that females contribute to offspring survival.

Understanding the selective pressures shaping the number of offspring per breeding event is a key area in the study of life-history strategies. However, in species with parental care, costs incurred in offspring production, rather than rearing, have been largely ignored in both theoretical and empirical studies until relatively recently. Furthermore, the few experimental studies that have manipulated production costs have not yet teased apart effects that operate via the parental phenotype from effects on the quality of the resulting young. To examine whether increased egg production influences parental brood rearing capacity independently of effects operating via egg quality, we experimentally increased egg production in gulls and then examined their capacity to rear a control clutch. We found that the capacity of parents to rear the control brood was substantially reduced solely as a consequence of having themselves produced one extra egg. The paradox that, in many species, parents apparently aim for fewer young per breeding event than the experimentally and theoretically demonstrated optimum, has partly arisen from the failure to take into account the constraints imposed by production costs.

Abstract.The breeding biology of the cave‐dwelling Mediterranean triplefin blennyTripterygion melanurus(Pisces, Blennioidei) was studied in the field. Two types of reproductive male were observed, territorial males and non‐territorial males. Territorial males establish territories for mating, but not necessarily for feeding, in caves and crevices at depths between 0.5 and 33 m. Territories can be settled in clusters in a single cave. Non‐territorial males occur in the vicinity of territories and attempt to parasitise matings of territorial males. Gravid females wait near territories where another female is spawning, rather than spawn with currently unmated territorial males. Waiting females intrude in matings and sometimes displace a spawning female. The frequency of mating of the territorial male, of sneaking and of female intrusions are higher in territories that border others than in isolated territories. Females may minimise predation risks both on themselves and on their eggs by spawning in clustered territories and by spawning with males that have more than one clutch of eggs. Territorial males must find a compromise between the benefits of attracting a female and the costs of parasitic spawning by sneaker males. The possibility that territorial males tolerate the proximity of other territorial males and accept a risk of cuckoldry is discussed. Parasitic spawning inT. melanurusis relatively rare and the gonadosomatic index in both non‐territorial and territorial males is low, indicating that sperm competition is probably not intense.

Egg laying, clutch brooding, egg survival and mate choice were investigated in the mid-wife toad, Alytes obstetricans (Lataste) at a small reservoir in central Spain during 1986 and 1987. Females divided their total egg production into at least three separate clutches. The majority of males brooded between one and three clutches of eggs, though one may have brooded four. First clutches received by males were 24-34% larger than subsequent clutches. No significant differences were found in egg fertilisation, survival and hatching success between individual clutches. The results show that females prefer to spawn with non-brooding males rather than brooding males but that they will spawn with brooding males. When spawning with brooding males they lay smaller clutches than with non-brooding males.

Operational sex ratio (OSR) is the ratio of the number of sexually mature males to the estrous females, which is used to predict the intensity of sexual selection. During the mating season (August－December 2007), we studied reproductive and aggressive behaviors in sexually mature male Tibetan macaques (Macaca thibitana) in two troops (YA₁ and YA₂) at Huangshan, China. The behavioral data were collected by focal animal sampling, ad libitum sampling and continuous recording. The purpose is to discuss the impact of OSR on mating competition of male Tibetan macaques. The OSR of YA₁ was 0.4:1, and the OSR of YA₂ was 0.9:1. The male-biased in OSR of YA₂ was higher than YA₁. The sexually mature males of high rank in YA₁ troop showed higher rates of reproductive behaviors than the males in YA₂: genital-inspecting, grimace, sexual chase and mating, respectively (P＜0.01). The sexually mature males of middle rank in YA₁ troop showed higher rates of reproductive behaviors than the males in YA₂: genital-inspecting, grimace, sexual chase (P＜0.01). The sexually mature males of middle rank in YA₁ troop also showed higher rate of mating behavior than the males in YA₂ (P＜0.05). However, there was no significant difference in reproductive behaviors between sexually mature males of low rank in two troops. The sexually mature males of high rank in YA₂ troop showed higher rate of aggressive behavior than the males in YA₁(P＜0.01). The sexually mature males of middle rank in YA₂ troop showed higher rate of aggressive behavior than the males in YA₁(P＜0.05). The sexually mature males of low rank in YA₁ troop didn&rsquo;t show any aggressive behavior. These results suggested that the intensification of male-biased in OSR can lead to the decrease of reproductive behaviors and the increase of aggressive behavior of male Tibetan macaques. The intensity of mating competition of sexually mature males in YA₂ troop was stronger than the males in YA₁. Our results support the prediction of the impact of OSR on mating competition by sexual selection theory.