Captive White-crowned Sparrows Research Articles

Experimental Exposure to Noise Alters Gut Microbiota in a Captive Songbird.

Noise pollution is an unprecedented evolutionary pressure on wild animals that can lead to alteration of stress hormone levels and changes in foraging behavior. Both corticosterone and feeding behavior can have direct effects on gut bacteria, as well as indirect effects through changes in gut physiology. Therefore, we hypothesized that exposure to noise will alter gut microbial communities via indirect effects on glucocorticoids and foraging behaviors. We exposed captive white-crowned sparrows to city-like noise and measured each individuals' corticosterone level, food intake, and gut microbial diversity at the end of four treatments (acclimation, noise, recovery, and control) using a balanced repeated measures design. We found evidence that noise acts to increase corticosterone and decrease food intake, adding to a growing body of research indicating noise exposure affects stress hormone levels and foraging behaviors. We also found evidence to support our prediction for a causal, positive relationship between noise exposure and gut microbial diversity, such that birds had higher measures of alpha diversity during noise exposure. These results help to explain previous findings that urban, free-living white-crowned sparrows have higher bacterial richness than rural sparrows. However, noise appeared to act directly on the gut microbiome or, more likely, through an unmeasured variable, rather than through indirect effects via corticosterone and food intake. Altogether, our study indicates that noise affects plasma corticosterone, feeding behavior, and the gut microbiome in a songbird and raises new questions as to the mechanism linking noise exposure to gut microbial diversity.

Preparing for Migration? The Effects of Photoperiod and Exercise on Muscle Oxidative Enzymes, Lipid Transporters, and Phospholipids in White‐Crowned Sparrows

The extreme energetic demands of avian migration result in various physiological changes that can be observed during the migratory period. However, the degree to which birds alter muscle physiology in advance of migration has been poorly studied. We studied the effects of "migratory" photoperiod and exercise on metabolic enzymes, fatty acid transporter mRNA expression, and muscle phospholipid fatty acid composition in captive white-crowned sparrows (Zonotrichia leucophrys). Ten sparrows were held on short photoperiod (8L:16D) for 58 d then switched to long days (16L:8D) for 3 wk before sampling. Increased nightly activity indicated that the birds were indeed in migratory condition. Another 13 birds were held on short days during the entire experiment, and a subset (5) were exercised for 1 h every other day for the last 2 wk. "Migratory" photoperiod did not change the activities of citrate synthase, carnitine palmitoyl transferase, and 3-hydroxyacyl-CoA dehydrogenase or the expression of FAT/CD36, FABPpm, and H-FABP mRNA in pectoralis muscle, suggesting that these cannot be increased in advance of migratory flight. Docosahexaenoic acid increased in pectoralis muscle phospholipids with exercise but was negatively correlated with catabolic enzyme activity, indicating that the presence of this fatty acid may not aid migratory performance as suggested by other studies.

Effects of repeated, short-term, corticosterone administration on the hypothalamo–pituitary–adrenal axis of the white-crowned sparrow ( Zonotrichia leucophrys gambelii)

Our knowledge of glucocorticoid actions in vertebrates comes primarily from laboratory studies, which are often conducted with little consideration of how animals experience changes in glucocorticoid secretion in natural contexts. Typically, free-living animals are exposed to acute perturbations of the environment, ranging from a few minutes to a few hours duration, with varying frequency. The cumulative effects of these perturbations and their resultant glucocorticoid surges are not well known. To investigate the possible cumulative effects of repeated, acute surges in glucocorticoid secretion, we developed an ecologically relevant methodology for treating captive white-crowned sparrows ( Zonotrichia leucophrys gambelii) with corticosterone (CORT). We dissolved CORT in dimethylsulfoxide (DMSO) and administered this cocktail directly on the skin. Treatments resulted in small elevations of CORT within the physiological range. In our first experiment at the end of the breeding life stage, birds were treated three times a day (3×). Two control groups were used: one treated with DMSO 3× and one not handled nor treated. In a second study at the beginning of the breeding life stage, one group was treated once a day and a second group 3×. A DMSO-control group was used for each dosage regime. Repeated, acute administration of CORT resulted in higher baseline CORT levels and a down-regulation of the endogenous adrenocortical response to a standardized stress. Maximum CORT and plasma corticosterone binding globulin levels increased in response to the CORT treatments only at the end of the breeding season. CORT treatment did not alter adrenal size, adrenal response to ACTH, or hepatic CORT metabolism.

Changes in brain gene expression during migration in the white-crowned sparrow

Long-term recordings of seasonal sleep patterns in captive white-crowned sparrows ( Zonotrichia leucophrys gambelii) have shown that these birds markedly reduce sleep time during the migratory period relative to the non-migratory period. It was also found that, despite this sleep reduction, sparrows showed no evidence of neurobehavioral deficits in a standard operant task used to assess the effects of sleep loss. In this study, we performed an extensive microarray analysis of gene expression in the sparrow telencephalon during the migratory season (M), relative to a 78-h period of enforced sleep restriction during the non-migratory season (SR), and a 6-h period of normal wakefulness during the non-migratory season (W). Of the estimated 17,100 transcripts that were reliably detected, only 0.17% changed expression as a function of M (relative to both SR and W), and 0.11% as a function of SR (relative to both M and W). Brain transcripts whose expression increased during M include the facilitated glucose transporter GLUT1, the presenilin associated rhomboid-like protein PARL, and several members of the heat shock protein family, such as HSP70, HSP90, GRP78 and BiP. These data suggest that migration is associated with brain cellular stress and enhanced energetic demands.

Migratory behaviour of captive white-crowned sparrows, Zonotrichia leucophrys gambelii, differs during autumn and spring migration

AbstractGambel's white-crown sparrow (Zonotorichia leucophrys gambelii) is a long-distance, over-land migrant. In captivity birds display many characteristics of the autumn and spring migratory life history stages that include hyperphagia, fattening and high intensity nocturnal activity termed migratory restlessness or Zugunruhe. We recorded the behaviour of captive birds while simultaneously collecting 24 h locomotor activity. These data were used to define the behaviour displayed by captive birds during autumn and spring in order to compare the two migratory stages and to draw inferences for free-living birds. The predominant behaviour during day and nighttime was rest. Feeding occurred only during daylight hours but at a greater frequency in autumn than spring. Birds generally used their feet as the primary source of locomotion during the day termed 'jump'. During the night, two distinct behaviours, 'beak-up flight' and 'beak-up' involving high intensity wing motions were observed and considered components of migratory restlessness. The frequency of the 'beak-up flight' was greatest during spring and associated with the enhanced tempo of vernal migration. In both stages, migratory restlessness was preceded by a quiescent phase, the occurrence of which differed and related to time available for foraging and length of the night. Given these findings, we hypothesize that diel behaviours displayed by autumn and spring migrants in captivity highlight distinctions between the two life history stages.

Plasma corticosterone increases during migratory restlessness in the captive white-crowned sparrow Zonotrichia leucophrys gambelli

Plasma corticosterone increases during the period of spring migration in a variety of bird species. Long-distance migrants show elevations in corticosterone specifically in association with the stage of flight, suggesting that corticosterone may support flight-related processes, for example, locomotor activity and/or energy mobilization. The pattern of corticosterone secretion as it relates to migratory flight has hitherto not been clearly described in migrants that frequently interrupt flight to refuel, for example, the Gambel's white-crowned sparrow ( Zonotrichia leucophrys gambelii). The Gambel's white-crowned sparrow fuels by day and expresses peak migratory activity during the first few hours of night. To determine if plasma corticosterone increases in association with the stage of migratory flight also in this short-bout migrant, we induced captive white-crowned sparrows to enter into the migratory condition by placing photosensitive birds on long days (16L:8D) and then evaluated birds for plasma corticosterone and locomotor activity during four time points of the day. Patterns found in long-day birds were compared to those observed in short-day controls (8L:16D). Differences in energy metabolism as determined from plasma metabolites were also evaluated. We found that locomotor activity and corticosterone were significantly elevated at the onset of the dark period, but only in long-day birds. Plasma β-hydroxybutyrate (a ketone body) was also elevated. Thus, findings suggest that plasma corticosterone and ketogenesis increase in association with migratory restlessness in a short-bout migrant. In fact, corticosterone may play a regulatory role, because it shows a trend to increase already before night-time activity.

Migratory sleeplessness in the white-crowned sparrow (Zonotrichia leucophrys gambelii).

Twice a year, normally diurnal songbirds engage in long-distance nocturnal migrations between their wintering and breeding grounds. If and how songbirds sleep during these periods of increased activity has remained a mystery. We used a combination of electrophysiological recording and neurobehavioral testing to characterize seasonal changes in sleep and cognition in captive white-crowned sparrows (Zonotrichia leucophrys gambelii) across nonmigratory and migratory seasons. Compared to sparrows in a nonmigratory state, migratory sparrows spent approximately two-thirds less time sleeping. Despite reducing sleep during migration, accuracy and responding on a repeated-acquisition task remained at a high level in sparrows in a migratory state. This resistance to sleep loss during the prolonged migratory season is in direct contrast to the decline in accuracy and responding observed following as little as one night of experimenter-induced sleep restriction in the same birds during the nonmigratory season. Our results suggest that despite being adversely affected by sleep loss during the nonmigratory season, songbirds exhibit an unprecedented capacity to reduce sleep during migration for long periods of time without associated deficits in cognitive function. Understanding the mechanisms that mediate migratory sleeplessness may provide insights into the etiology of changes in sleep and behavior in seasonal mood disorders, as well as into the functions of sleep itself.

Ptilochronology: A Critical Evaluation of Assumptions and Utility

ABsTRAcr.-Ptilochronology has been proposed as a method that will open up many new lines of investigation in nutritional ecology, in foraging behavior, and of life-history variables that are affected by (or affect) a bird's nutritional status. The method depends on measurements of a series of daily growth bars to estimate a feather's growth rate, and thereby to quantitate a bird's nutritional status while the feather was growing. The reliability of the method as proposed depends on the fulfillment of several previously unstated assumptions. We identified seven key assumptions and, in experiments with captive White-crowned Sparrows (Zonotrichia leucophrys gambelii), examined the likelihood that six of the assumptions could be fulfilled. The seventh assumption, no less crucial than the others, could not be tested empirically. None of the six tested assumptions were consistently fulfilled. Only lethal kinds or levels of nutritional privation consistently slowed feather growth. Moderate or even severe sublethal privation did not produce consistent effects on feather growth. In short, ptilochronology as originally conceived is fraught with uncertainty. It may yield reliable results in very limited, carefully controlled conditions, but this remains to be proved. Received 23 August 1990, accepted 20 December 1990.

Malnutrition during the postnuptial molt of White-crowned Sparrows: feather growth and quality

It has often been alleged that avian molt can be interrupted or delayed by food deprivation or malnutrition. We examined this experimentally in captive White-crowned Sparrows (Zonotrichia leucophrys gambelii). Beginning either at the natural onset of postnuptial molt or 1 month before its onset, groups of birds were fed either inadequate amounts of a balanced diet (60 or 80% of the ad libitum intake of a control group) or unlimited amounts of a diet deficient only in cyst(e)ine and methionine. Except in the 60% premolt group, the malnourished birds did not postpone or interrupt molt in spite of losses ranging from 20 to 38% of initial body mass. Molt was significantly protracted in all except the 60% premolt group as a result of both increased shedding interval and decreased feather growth rates. Their new plumage weighed less than that of control birds, and their remiges were slightly shorter and often deformed or achromatic. The occurrence of fault bars corresponded to the times when the birds were handled, but was not correlated with other plumage defects. Surviving birds of the 60% premolt group did not molt until allowed to feed ad libitum, but then produced a normal plumage in about two-thirds of the time required by the controls. To summarize, molt is a very conservative aspect of self maintenance that is distorted only by planes of malnutrition that free-living sparrows either do not encounter during the summer or do not survive.

Signals of status in wintering white-crowned sparrows, Zonotrichia leucophrys gambelii

The possibility of plumage status signalling within the social systems of wintering birds has been a controversial issue. Our results are the first to demonstrate conclusively the reality of such signalling. Data from eight groups of captive white-crowned sparrows ( Zonotrichia leucophrys gambelii), each with 8 to 11 different individuals, show that immature and adult females with crowns painted to resemble more brightly coloured, dominant adult males consistently win encounters with control birds of their own age and sex. These experiments demonstrate that signals that correlate with age (adult versus immature) and sex (adult male versus adult female) are used by the birds as reliable indicators of relative dominance position. Our demonstration of status signalling draws attention to the need to explain how such a system can be evolutionarily stable and we discuss some suitable models.

Effects of Photoperiod and Temperature on Postnuptial Molt in Captive White-Crowned Sparrows

Journal Article Effects of Photoperiod and Temperature on Postnuptial Molt in Captive White-Crowned Sparrows Get access John D. Chilgren John D. Chilgren Corvallis Environmental Research Laboratory, U.S. Environmental Protection Agency, 200 SW 35th St., and Department of Zoology, Oregon State University, Corvallis, Oregon 97331 Search for other works by this author on: Oxford Academic Google Scholar The Condor, Volume 80, Issue 2, 1 April 1978, Pages 222–229, https://doi.org/10.2307/1367922 Published: 01 April 1978 Article history Accepted: 18 April 1977 Published: 01 April 1978

Body Composition of Captive White-Crowned Sparrows during Postnuptial Molt

-A five-compartment analysis of body composition was performed on indoor and outdoor captive White-crowned Sparrows before, during, and after their postnuptial molt. Body weight was monitored simultaneously in four experimental groups. The duration of postnuptial molt in indoor and outdoor birds averaged 60 days. The body weight of outdoor captives in Pullman changed similarly to that seen during the early stages of molt in Fairbanks captives, although late molt autumnal fattening is less intense and more irregular in Pullman captives. Birds on a constant photoperiod at 50 and 15?C exhibited early weight gains, but these gains were either unsustained or converted to weight losses as molt progressed. Total body water in lean birds averaged 70% during molt and 68% after molt. The absolute weight of body water as well as body weight increased during molt. Thus the fractional TBW was essentially unchanged. The stability of the plumage-free lean body mass during molt reflected the negligible extent to which body protein is catabolized, although nocturnal protein degradation was not examined. The lean body weight during molt averaged 23.8% of the lean wet weight, plumage free, or about 5.6 g, but both these figures were only slightly higher after the molt. Plumage weight during the molt increased about 30%. Body feathers constituted the largest fraction (ca. 75%) of the plumage mass, even during molt. Plumage weight after molt was about 24% of the lean dry weight. Body lipid reached its nadir at the onset of molt in Fairbanks captives (LI = 3.5), but increased 6to 7-fold at the end of molt (LI = 20). In Pullman outdoor captives, the increment was about 5-fold. Indoor captives vary in postmolt fattening, depending perhaps upon prior photoperiodic history before transfer to a constant photoperiodic environment. Thus some individual birds transferred later in the spring showed some degree of postmolt fattening, whereas those transferred earlier showed none. This is but a tentative conclusion. Although lipid reserves in the White-crowned Sparrow are small at the onset and perhaps most critical period of molt, the long feeding period and the mutual exclusion of the breeding and molting schedules preclude any apparent calorific drain on the avian body. It is suggested that the rapid molt period may be a selective force operating to separate temporally two events of the annual cycle that are potentially costly energetically.-Department of Zoology, Washington State University, Pullman, Washington 99164. Present address: Department of Zoology, Oregon State University, Corvallis, Oregon 97331. Accepted 26 January 1976. THE YEARLY cycle of all passerines includes an annual molt, which usually begins after breeding or during its later stages. The Gambel Sparrow, Zonotrichia leucophrys gambelii, a member of the west coast complex of North American Whitecrowned Sparrows, molts after the cessation of all breeding activities while on its Alaskan and Canadian breeding grounds (see Cortopassi and Mewaldt 1965, for the distribution of this species), and has been reported to complete its postnuptial molt in 7 weeks (Morton et al. 1969), although this may be subject to some year-to-year variation (Chilgren 1975). In several passerines studied, the molt is usually characterized at some point early in the sequence by an increase in body weight (King et al. 1965, Newton 1968, Myrcha and Pinowski 1970, Morton and Welton 1973), suggesting that the molt does not exact a physiological hardship upon the animal, as might be expected in these birds that molt within 2 months. But body weight is not an appropriate index of the physiological impact of molt, and may mask the potential nutritional stress of a molt. Thus increases in body water, for example, may appear concurrently with decreases in body lipid or protein with little or no change in the bird's live weight or energy reserves. Only a few studies of molt have examined the 677 The Auk 94: 677-688. October 1977 This content downloaded from 157.55.39.136 on Thu, 01 Dec 2016 05:45:11 UTC All use subject to http://about.jstor.org/terms 678 JOHN D. CHILGREN [Auk, Vol. 94

Effect of Temperature and Exercise on Energy Intake and Body Weight of the White-Throated Sparrow Zonotrichia albicollis

Effect of Temperature and Exercise on Energy Intake and Body Weight of the White-Throated Sparrow Zonotrichia albicollis