Reproduction In Zebra Finches Research Articles

An experimental test of chronic traffic noise exposure on parental behaviour and reproduction in zebra finches.

ABSTRACTChronic traffic noise is increasingly recognised as a potential hazard to wildlife. Several songbird species have been shown to breed poorly in traffic noise exposed habitats. However, identifying whether noise is causal in this requires experimental approaches. We tested whether experimental exposure to chronic traffic noise affected parental behaviour and reproductive success in zebra finches (Taeniopygia guttata). In a counterbalanced repeated-measures design, breeding pairs were exposed to continuous playback of one of two types of highway noise previously shown to be either neutral (control) or aversive. Parental nest attendance positively correlated with feeding effort and was higher for the aversive than the control sound and this effect was more pronounced for parents attending larger broods. However, neither noise condition affected offspring number, growth or body mass. The absence of an effect held when we combined our data with data from two other comparable studies into a meta-analysis. We discuss whether the increased nest attendance could be a compensatory strategy that alleviated detrimental noise effects on the chicks, and whether it could be caused by impaired parent-offspring or within-pair communication. Future work should test these hypotheses and investigate potential long-term costs of increased parental engagement.

In ovo tris(2-butoxyethyl) phosphate concentrations significantly decrease in late incubation after a single exposure via injection, with no evidence of effects on hatching success or latent effects on growth or reproduction in zebra finches.

Zebra finch (Taeniopygia guttata) eggs were injected with the organophosphate triester flame retardant tris(2-butoxyethyl) phosphate (TBOEP) at 0 μg/g, 0.01 μg/g, 1 μg/g, 10 μg/g, or 50 μg/g egg. Subsets of high-dose eggs were collected throughout incubation to measure TBOEP, which started declining in late incubation and then decreased rapidly to 28% of injected concentration by hatching. The authors found no effects of TBOEP on survival, growth, or reproduction even at very high doses. Environ Toxicol Chem 2017;36:83-88. © 2016 SETAC.

Active immunization against vasoactive intestinal polypeptide decreases neuronal recruitment and inhibits reproduction in zebra finches.

Neurogenesis and neuronal recruitment occur in adult brains of many vertebrates, and the hypothesis is that these phenomena contribute to the brain plasticity that enables organisms to adjust to environmental changes. In mammals, vasoactive intestinal polypeptide (VIP) is known to have many neuroprotective properties, but in the avian brain, although widely distributed, its role in neuronal recruitment is not yet understood. In the present study we actively immunized adult zebra finches against VIP conjugated to KLH and compared neuronal recruitment in their brains, with brains of control birds, which were immunized against KLH. We looked at two forebrain regions: the nidopallium caudale (NC), which plays a role in vocal communication, and the hippocampus (HC), which is involved in the processing of spatial information. Our data demonstrate that active immunization against VIP reduces neuronal recruitment, inhibits reproduction, and induces molting, with no change in plasma prolactin levels. Thus, our observations suggest that VIP has a direct positive role in neuronal recruitment and reproduction in birds. J. Comp. Neurol. 524:2516-2528, 2016. © 2016 Wiley Periodicals, Inc.

Impact of kin odour on reproduction in zebra finches

Although it has long been disregarded, the accumulating evidence suggests that birds use chemical cues for communication. However, the impact of olfaction on avian mate choice and its potential function in inbreeding avoidance remain unknown. We compared the mate choice and reproductive behaviour between females experimentally deprived of their sense of smell and intact control females. Each female was allowed to mate with two unfamiliar males, an unrelated male and a full brother. If olfactory cues are involved in kin recognition and/or mate choice, we expect the smelling females to reproduce with the unrelated males and the anosmic females to mate randomly with respect to relatedness. The paternity analysis revealed that the anosmic females reproduced randomly with respect to relatedness. Contrary to our expectations, the females with an intact olfactory mucosa demonstrated a decrease in reproduction; they produced significantly fewer eggs than the anosmic females, and the chicks in only one of the cages reached independence. Thus, the female’s ability to smell in the presence of the unfamiliar brother had the unexpected effect of impairing the reproductive behaviour of the females. This is the first study to report directly the critical role of olfactory signals in reproduction and its potential function in preventing maladaptive breeding attempts with kin in female songbirds.

Context-dependent effects of carotenoid supplementation on reproduction in zebra finches

Carotenoid-dependent sexual coloration is one of the best-studied sexual signals, but how the honesty of such signals is maintained remains uncertain. The main hypotheses focus on acquisition limits and physiological use of carotenoids in immune function and regulating oxidative stress. A hypothesis that has received less attention states that carotenoids can also be detrimental, depending on an animal's state. Hence, carotenoid-dependent signals may be a handicap, signaling the ability to evade or tolerate detrimental effects of carotenoids. To investigate this hypothesis, we examined the effects of carotenoid supplementation on subsequent reproduction in zebra finches in 2 different foraging environments (easy and hard), thereby generating variation in physiological state. We find support for context-dependent negative effects of carotenoid supplementation on subsequent laying latency and on total number of eggs laid: carotenoids had a detrimental effect in the easy conditions and a beneficial effect in the hard conditions. Thus, our results support the hypothesis that carotenoids can have context-dependent detrimental effects. Dissecting the relative contribution of the different mutually nonexclusive honesty mechanisms-acquisition, physiological benefits, and context-dependent detrimental effects of carotenoids-maintaining carotenoid-dependent signal honesty will be an exciting challenge.

Familial differences in the effects of mercury on reproduction in zebra finches

Ecotoxicologists often implicitly assume that populations are homogenous entities in which all individuals have similar responses to a contaminant. However, genetically variable responses occur within populations. This variation can be visualized using dose–response curves of genetically related groups, similar to the way that evolutionary biologists construct reaction norms. We assessed the variation in reproductive success of full-sibling families of captive zebra finches (Taeniopygia guttata) experimentally exposed to methylmercury. We found significant variation among families in the effects of methylmercury on several reproductive parameters. This variation suggests that there may be strong responses to selection for resistant genotypes in contaminated areas. This has important implications for the evolution of tolerance as well as risk assessment and wildlife conservation efforts on sites with legacy contamination.

Parental and First Generation Effects of Exogenous 17β-Estradiol on Reproductive Performance of Female Zebra Finches (Taeniopygia guttata)

Steroids hormones have numerous “activational” effects in adult birds, regulating sexual behavior, and more recently maternal androgens have been shown to have potentially important “organizational” effectsin ovo,influencing offspring growth, development, and behavior. In this study I investigated parental and first-generation effects of exogenous estrogens on female reproduction in zebra finches (Taeniopygia guttata). 17β-Estradiol (E2; 1.2 μg/g, 4 daily injections i.m.) elevated plasma levels of the yolk precursors, vitellogenin (VTG) and very low-density lipoprotein (VLDL), in nonbreeding females to levels similar to those of breeding females. However, E2-treatment of breeding females caused no significant change in plasma VTG or VLDL levels compared to control birds (measured at the 1-egg stage), and there was no difference in reproductive performance between groups (egg size, clutch size, timing of laying). E2-treated females produced significantly more daughters than sons (21F:8M) at fledging, compared to control females (18F:19M). Nestling mortality was significantly higher in broods of E2-treated females, suggesting that the skewed sex ratio may have resulted from differential mortality of male chicks. The pattern of chick mortality in E2-broods was not consistent with this being caused by estrogen-mediated changes in parental behavior (e.g., provisoning). Mean egg mass of daughters of E2-treated females was typical of experienced, adult breeders, and larger than normal, first-time breeders or control offspring (0.947 vs 0.850 g). There was no treatment effect on offspring clutch size or laying interval. These results suggest that early exposure to maternal estrogensin ovomight be involved in establishing intraindividual variation in female-specific phenotypic traits, as has previously been demonstrated for androgens and male behavioral traits (e.g., aggression).

Effects of the organophosphorus pesticide fenitrothion on behavior and reproduction in zebra finches

Activity was significantly altered in zebra finch pairs orally dosed with fenitrothion insecticide at rates of 1.04 and 3.80 mg/kg. Both the level and the dirunal pattern of activity were affected. Recovery of normal activity required 1-2 days, depending on the dosage administered. Fenitrothion had only a slight effect on reproduction when parents were dosed at the egg-laying stage of the breeding cycle. The implications of these results for the interpretation of field monitoring studies are discussed.

Reproduction in Zebra Finches: Hormone Levels and Effect of Dehydration

-Zebra Finches (Poephila guttata) of arid Australia can breed continuously under favorable conditions. During droughts, however, breeding ceases but is said to begin again immediately after rain. We found that testis size in breeding birds did not change during, or between, reproductive cycles. Luteinizing hormone (irLH) levels in plasma, however, were significantly higher in males during early incubation (1.25 ng/ml), and in females during courtship (0.89 ng/ ml), than during other parts of the reproductive cycle. Plasma levels of the sex steroids were highest (1.06 ng/ml for androgen in males, 0.32 ng/ml for estrogens in females) at the same time that irLH levels were highest. Wild-caught Zebra Finches had, at capture, testes similar in size to those of aviary-breeding Zebra Finches, but after three weeks of dehydration (1 ml water/bird/week), testis size was significantly smaller and hematocrit was significantly higher: 54% vs. 50% for birds given unlimited access to water. When dehydrated birds were given unlimited access to water, testes grew significantly. Access to green grass or exposure to high relative humidity (85%) augmented the effects of the water on testis size. Spermatogenic activity in some dehydrated birds was high despite small gonad size; however, interstitial tissue was poorly developed, and plasma levels of sex steroids and irLH were low. We suggest that Zebra Finches normally maintain gonadal tissue in a functioning state unless severely dehydrated. Relief from dehydration is a necessary, but not sufficient, condition for the full expression of reproduction. For species that do not live in temporally uniform environments, the timing of reproduction can be a critical element in reproductive success. In many temperate zone birds, reproductive activity begins during the spring, when increasing daylength provides a dependable cue that indicates the approach of conditions favorable for reproduction (see reviews in Lofts and Murton 1968, Farner 1970, Farner and Lewis 1971, Wingfield and Farner 1980). Compared to daylength, other environmental cues that may play a role in controlling the timing of reproduction have received little attention (Moreau 1950, Marshall and Disney 1957, Marshall 1970, Immelmann 1971, Wingfield 1980, Earle 1981, Storey and Nicholls 1982). In some habitats, daylength may not be a reliable cue for reproduction because the onset of other favorable conditions is independent of the changes in daylength. Desert birds, for example, may encounter suitable conditions for reproduction only for brief periods after rainfall, and in such species rapid initiation of reproduction in response to rainfall, regardless of daylength or season, may maximize reproductive success. Such breeding in response to rain apparently occurs in the Zebra Finch (Poephila guttata, syn: Taeniopygia guttata castanotis) native to the arid interior of Australia. The reproductive state of Zebra Finches is not influenced by daylength (Marshall and Serventy 1958, Oksche et al. 1963, Sossinka 1975). In the mesic parts of their range, or in areas receiving agricultural irrigation, Zebra Finches breed year-round, except in the coldest winter months, with peaks in nesting attempts occurring in spring and in autumn (Frith and Tilt 1959, Kikkawa 1980). In arid central Australia, however, the species breeds following the irregular rains, regardless of the time of year (Immelmann 1965). Davies (1977), in a two-year study of Zebra Finches in Western Australia, found birds breeding in every month except March, April, and August, and suggested that both rainfall and temperature were important in the initiation of breeding. Immelmann (1963, 1965) reported that Zebra Finches copulated within a few hours of the beginning of the first rain following several months of drought, and began nesting and egglaying within one week. Zebra Finches are capable of producing many offspring under favorable conditions because (1) both members of the pair participate in nest building (Immelmann 1963), (2) a pair will nest repeatedly as long as conditions remain favorable (Ser-

Effects of dehydration on reproduction in zebra finches

Effects of dehydration on reproduction in zebra finches

Gaseous Metabolism and Water Relations of the Zebra Finch, Taeniopygia castanotis

Gaseous Metabolism and Water Relations of the Zebra Finch, Taeniopygia castanotis