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PubMed1984

Environmental and endocrine control of reproduction in the song sparrow, Melospiza melodia. I. Temporal organization of the breeding cycle.

Endocrinologic investigations of free-living populations of song sparrows, Melospiza melodia, have revealed temporal patterns of secretion of reproductive hormones that differ from those of other monogamous avian species. Males arrive in the breeding area in March whereas females arrive 1-2 weeks later. In males the periods of territory establishment and attraction of a mate are characterized by high circulating levels of luteinizing hormone (LH) and testosterone (T), whereas testis mass is low, and growth of the cloacal protuberance (CPL) is just beginning. In April, testes and CPL develop rapidly reaching a peak in early May when females are laying eggs, and when most copulations occur. Plasma LH and T decline in early April, but increase for a second time in late April and early May coincident with the egg-laying period. Thereafter, circulating LH and T decline during the parental phase, but not to basal levels. Although there is an increase in LH during the egg-laying period for the second clutch, there is no change in T levels. Testis mass, CPL, plasma LH, and T all decline to basal levels simultaneously in late July and August. The high levels of LH and T in March, followed by a temporary decline and resurgence in April and May, indicate that environmental factors in addition to the well known effects of increasing day length can regulate secretion of these hormones. In females, plasma levels of T and dihydrotestosterone (DHT) are also elevated in March and early April, and decline to low levels as the nesting phase progresses. A further decline, to basal levels, occurs in August during the molt. LH and estradiol (E2) titers in females show two peaks coincident with the egg-laying periods for each clutch. Plasma levels of corticosterone (B) increase during the breeding season in males, but not females. In both sexes B levels are basal during the moult and increase in October after moult is completed. Body mass and fat depot decline in males as the nesting phase progresses, and then increase dramatically after breeding is terminated. As expected, females show two peaks of body mass and fat depot coincident with the two periods of egg laying. The postbreeding increases in body mass and fat depot are much less pronounced in females than in males.

Adipose Tissue↗

PubMed1988

Effects of ovariectomy on long-day-induced premigratory fat deposition, plasma levels of luteinizing hormone and prolactin, and molt in white-crowned sparrows, Zonotrichia leucophrys gambelii.

Long days initiate the hyperphagia, fat deposition, and nocturnal restlessness, characteristic of the vernal migratory state in white-crowned sparrows. Ovariectomy, when performed in November, but not when performed in January, prevented induction by long days (20L:4D) of vernal fat deposition, whereas autumnal fat deposition was not affected. This is consistent with results obtained previously with males. Very high plasma levels of luteinizing hormone (LH) after photostimulation of ovariectomized females did not interfere with fat deposition. During fat deposition, levels of prolactin were not different from short-day levels and similar in ovariectomized and control females. However, ovariectomy performed in November suppressed the maximum levels of prolactin produced by long-day stimulation and inhibited or disturbed postnuptial molt. These effects were absent when ovariectomy was performed in January. Long-day-induced prolactin levels were higher when birds were photostimulated during a later phase of the annual cycle. It is suggested that castration does not interfere with long-day-induced vernal fat deposition via reduced secretion of prolactin in the absence of ovarian hormones or via supernormal secretion of LH, but that vernal fat deposition, prolactin secretion, and postnuptial molt require the presence of ovarian hormones prior to photostimulation. Autumnal migratory fat deposition, which is part of the cluster of events associated with photorefractoriness, has no requirement for gonadal hormones.

Adipose Tissue↗

PubMed1990

Extraocular control of seasonal reproduction in female tree sparrows (Spizella arborea).

The work reported here explored extraocular control of seasonal reproduction in a photoperiodic species. Photosensitive female tree sparrows (Spizella arborea) were subjected to bilateral or unilateral ocular enucleation or to sham operation and exposed to a photoregimen designed to stimulate luteinizing hormone (LH) secretion, to induce photorefractoriness, and to restore photosensitivity. As revealed by plasma LH profiles constructed from measurements taken over 181 days, neither bilateral nor unilateral ocular enucleation had a substantive effect on photoinduced LH release, on the development of photorefractoriness, or on the recovery of photosensitivity. In a related experiment, photorefractory sighted females were implanted epicranially with miniature self-powered lights (SPLs) or with non-emitting helium blanks (HBs) and transferred to short days. After 8 weeks, SPLs and HBs were removed, and birds were challenged with long days. As indicated by plasma LH and ovarian responses to the challenge, previously HB-implanted birds had regained photosensitivity, but previously SPL-implanted birds remained photorefractory. When interpreted within the context of the effects of blinding, these findings suggest that an extraocular encephalic mechanism maintains photorefractoriness. Collectively, the data support the hypothesis that photoinduced LH release and the biannual transitions between photosensitivity and photorefractoriness are controlled by an extraocular mechanism(s).

Animals↗

PubMed1987

Plasma androgens and aggressiveness in captive winter white-throated sparrows (Zonotrichia albicollis).

Captive white-throated sparrows (Zonotrichia albicollis), held under a natural photoperiod, were pair tested to evaluate dominance and aggressiveness in relation to plasma androgen levels and plumage morphology. Androgen levels were determined in November, 1 week before behavioral testing began; in January, at the conclusion of behavioral testing; and again in March. November plasma androgen levels of captive birds did not differ from those of a group of feral birds and were greater than androgen levels in January and March. Androgen levels of male and female white-striped and tan-striped birds did not differ for any collection date. November plasma A levels were significantly positively correlated with the display of aggressive behaviors by test birds and were inversely correlated, though not significantly, with hierarchy position. Plasma androgen levels determined in January and March were not related to aggressiveness or dominance. These data suggest that circulating androgens and morphological characters may act synergistically, at the onset of flock formation, to influence avian winter dominance hierarchies.

Aggression↗

PubMed1984

Energy enzymes of the flight muscle of the house sparrow, Passer domesticus--III. Comparative physical properties of heart and flight muscle lactate dehydrogenase.

Purification of heart (LDH-4) and flight muscle (LDH-2 and LDH-3) lactate dehydrogenase isoenzymes from the house sparrow, Passer domesticus, has been accomplished. Although these isoenzymes electrophoretically migrate reversed to most other vertebrate LDH isoenzymes, comparison of the amino acid compositions of LDH-4 and LDH-2-LDH-3 fails to reveal the basis for their reversed electrophoretic migration. Amino acid compositions did reveal mol. wts between 141,000-142,000 as well as vp of 0.744 ml/g (LDH-4) and 0.745 ml/g (LDH-2-LDH-3). SDS-gel electrophoresis yielded single bands for each preparation with mol. wts of 35,000 suggesting that LDH in this species exists as a tetramer. LDH-4 has a lower Km for both pyruvate (0.005 mM) and NADH (0.002 mM) than does LDH-2-LDH-3 (0.062 mM for pyruvate, 0.013 mM for NADH).

Amino Acids↗

PubMed1989

Sparrows discriminate between diets differing in valine or lysine concentrations.

White-crowned Sparrows (WCS) were given free access to pairs of semisynthetic diets that were either adequate or subadequate (25% of requirement) in valine or lysine. Within 2 to 4 days WCS chose a ratio of the paired diets that allowed them to maintain body mass or restore any losses quickly. On the initial choice days the birds transiently reduced total daily food intake (TDFI) roughly in proportion to their intake of the subadequate diet. The initial decrease of TDFI was greater and the latency in choosing an effective ratio of the paired diets was 2-3 days longer with valine than with lysine diets in well-nourished test birds. In malnourished birds fed only the subadequate test diet for 3 days, valine-deficient birds increased TDFI and body mass more promptly than did lysine-deficient birds when offered a choice of adequate and subadequate diets. The form of the test amino acid (CAA = crystalline, PB = protein-bound) had little effect on choice behavior, but sudden transfer of WCS from a PB acclimation diet to test diets with a large total CAA concentration increased the latency of effective choice by 2-3 days. A brief acclimation (2-3 days) to a CAA diet precludes any bias between nutritionally equivalent CAA and PB diets. The small differences in choice dynamics between valine and lysine and between dietary forms may help to identify mechanisms involved in food choice but are probably ecologically insignificant to free-living WCS. These birds are very adept at selecting diets that satisfy their amino acid requirements.

Animals↗

PubMed1991

Endogenous circadian rhythm in the photoperiodic ovarian response of the subtropical sparrow, Passer domesticus.

Groups of photosensitive female house sparrows have been kept under night-interruption and intermittent light cycles for a period of 6 weeks. The night-interruption cycle consisted of a basic photophase of 6 h and 1 h photointerruption of the dark phase in the 24 h cycle at different points. Ovarian growth was stimulated under cycles in which photointerruption of the dark phase was made 10 h after the onset of basic photophase. The intermittent light cycles consisted of 2 L:2 D, 3 L:3 D, 4 L:4 D, 8 L:8 D and 12 L:12 D besides two control groups held on 7 L:17 D and 17 L:7 D. Ovarian response was observed only in 2 L:2 D, 3 L:3 D, 4 L:4 D, 12 L:12 D and 17 L:7 D cycles. The results of both the experiments are consistent with an avian external coincidence model and indicate that circadian rhythmicity is involved during the initiation of the female avian reproductive system.

Animals↗

PubMed1980

Midbrain regions involved in call production in Java sparrows.

Calling has been evoked from the midbrain of Java sparrows by currents of less than 200 micro A. Minimum thresholds were found in the medial nucleus intercollicularis, higher threshold sites surrounded these. Additionally, more ventral sites were found. Calling evoked did not resemble natural calls, but was similar to that produced after bilateral denervation of the syrinx. These results indicate that the nucleus intercollicularis acts as a controller rather than an organizer of calling.

Animals↗

PubMed1985

Changes in the blood and plasma volume of Harris' sparrows during postnuptial molt.

In captive Harris' sparrows (Zonotrichia querula), plasma and blood volume increased significantly during stages 2 and 3 of postnuptial molt, when extensive feather replacement was taking place in the wings, tail and body tracts. Erythrocyte number did not increase significantly until molt was essentially complete. Consequently the 6% mean maximum reduction in hematocrit that was observed during molt appeared to be largely the result of plasma volume expansion. This plasma volume expansion was not due to changes in the osmolality or concentration of proteins within the blood plasma since both decreased significantly during intense molt.

Animals↗

PubMed1983

Energy enzymes from the flight muscle of the house sparrow, Passer domesticus-II. Physical and chemical properties related to purification of the glycolytic enzymes.

The isoelectric points (pI0), molecular weights and ammonium sulfate precipitation ranges for most of the glycolytic enzymes from house sparrow (Passer domesticus) flight muscle were determined. The pI0 for each enzyme is as follows: HK (6.8), PGI (6.7), PFK (5.4), Ald (7.2), TPI (7.5), PGK (7.1), PGM (6.1), Enol (6.2), PyK (6.6), and LDH (8.3). The molecular weight for each enzyme is as follows: PGI (145,000), Ald (160,000), TPI (60,000), PGK (35,000), PGM (60,000), Enol (100,000), PyK (200,000), and LDH (145,000). The ammonium sulfate precipitation range for each enzyme is as follows: PGI (0-80%), PFK (40-50%), Ald (40-65%), TPI (30-90%), PGK (70-90%), PGM (30-80%), Enol (45-80%), PyK (55-85%), and LDH (40-65%).

Ammonium Sulfate↗

PubMed2026

Coronavirus surveillance in passerines reveals novel deltacoronaviruses in Eurasian tree sparrows with implications for One Health and livestock biosecurity.

Coronaviruses (CoVs) are widespread RNA viruses infecting a broad range of avian and mammalian hosts. Although gammacoronaviruses and deltacoronaviruses (DCoVs) are common in wild birds, their presence in Eurasian passerines remains poorly understood. We screened 243 birds (35 species) at migratory stopover sites in Slovenia (2020-2021) using pan-coronavirus RT-PCR. Coronavirus RNA was detected only in four Eurasian Tree Sparrows (Passer montanus). Whole-genome sequencing yielded genomes of 26,017-26,018 bp with high internal conservation (99.95-99.98% identity). Phylogenetic analysis revealed notable evolutionary incongruence: isolates were highly related to porcine DCoVs in the ORF1ab region (95.6-96.1% amino acid identity) but clustered with divergent avian DCoVs in the spike gene (75.7-76.8% identity). RDP5 analysis provided strong evidence for a large-scale recombination event (p = 1.17 × 10-43), consistent with a mosaic genomic architecture combining an ORF1ab region closely related to porcine DCoVs with an avian-associated spike gene. This genomic pattern highlights evolutionary connectivity among DCoVs associated with different host groups and the potential role of recombination in changes in host association. The synanthropic behaviour and mobility of P. montanus facilitate contact with diverse hosts, making this species relevant for investigating DCoV ecology at wildlife-livestock interfaces. These findings represent the first genomic characterisation of DCoVs in P. montanus in Europe and support the inclusion of passerines in broader coronavirus surveillance. Genomic surveillance of underrepresented wild-bird hosts can improve our understanding of DCoV diversity, recombination, and evolution across wildlife-livestock interfaces.

Cross-species transmission↗

PubMed2004

Absorption and paracellular visualization of fluorescein, a hydrosoluble probe, in intact house sparrows (Passer domesticus).

We describe a method to visualize the cellular location of compounds during absorption by the small intestine in intact animals. First, we employed pharmacokinetic methodology to measure the fractional absorption of sodium fluorescein, a small (MW = 376) water-soluble molecule that is widely used as hydrophilic marker molecule for paracellular permeability studies. Based on the hypothesis that the paracellular pathway acts as a sieve, we predicted that fluorescein absorption would be considerable, but less than that of passively absorbed L-glucose which is a smaller molecule (MW = 180). When the two compounds were gavaged into house sparrows simultaneously, the birds absorbed significantly less fluorescein (42 +/- 8%) than L-glucose (82 +/- 7%), as predicted, and absorptions of the two were correlated as one would predict if they shared the same pathway. We removed intestinal tissue 10 min after gavage with sodium fluorescein and determined the cellular location of the compound's fluorescence using confocal laser microscopy. The fluorescent signal was found primarily in the paracellular space. In contrast, in the same type of experiment using instead the similar-sized fluorescent lipophilic compound rhodamine 123 (MW = 381), most fluorescence appeared inside enterocytes, as expected for a compound that diffuses across the apical membrane. Thus, results from all the experiments are consistent with the hypothesis that hydrophilic fluorescein is absorbed primarily via a paracellular pathway. These methods could be applied to visualize absorption pathways of other compounds in other intact animals.

Journal Article↗

PubMed2003

Effects of temperature on photoperiodically induced reproductive development, circulating plasma luteinizing hormone and thyroid hormones, body mass, fat deposition and molt in mountain white-crowned sparrows, Zonotrichia leucophrys oriantha.

The mountain white-crowned sparrow, Zonotrichia leucophrys oriantha, breeds in subalpine meadows throughout many mountainous regions of western North America. Mathematical analysis of 20 years of egg-laying dates at Tioga Pass, California (3030m elevation) indicated a highly predictable breeding season suggesting that precise environmental cues such as the annual change in day length were important for regulating reproductive function. Additionally, it appeared that there was sufficient yearly variation in the timing of breeding to suggest that other environmental cues may also be important for regulating adjustments in reproductive development and regression. Captive populations of Z. l. oriantha showed strong responses in gonadal development following transfer to longs days (15L 9D) and low temperature (5 degrees C) slowed down photoperiodically induced gonadal growth and subsequent regression, in both males and females. High temperature of 30 degrees C tended to accelerate gonadal development and regression whereas gonadal development was intermediate in a group exposed to 20 degrees C. Prior exposure to these temperature regimes while on short days (9L 15D) had no effect on body mass, fat, or plasma levels of luteinizing hormone (LH) and thyroid hormones. Curiously there was no effect of temperature on photoperiodically induced rises in LH in either sex despite marked effects on gonadal growth. Brood patch development was also enhanced in females exposed to 30 degrees C. Corticosterone levels measured in a subset of plasma samples from this experiment indicated no effect of temperature suggesting that the retarded gonadal development at 5 degrees C was not a result of thermal stress. Although there was a robust effect of photostimulation on thyroid hormone levels in blood of both sexes, temperature treatment had no effect on tri-iodothyronine (T3) concentrations. However, plasma levels of thyroxine (T4) were lower initially at 5 degrees C versus 20 and 30 degrees C treatments. This may be related to the protracted gonadal cycle at 5 degrees C versus the truncated gonadal cycle at 30 degrees C. Molt score, an indication of post-reproductive state and onset of photorefractoriness, was delayed in birds exposed to 5 degrees C. Body mass, and to a lesser extent fat score, tended to be lowest in birds exposed to 5 degrees C compared with those at 20 and 30 degrees C. These results demonstrate that ambient temperature significantly affected photoperiodically induced gonadal development and regression in these birds. The endocrine mechanisms underlying these effects require further study.

Adipose Tissue↗

PubMed2002

Cytological steps during spermiogenesis in the house sparrow (Passer domesticus, Linnaeus).

Spermiogenesis of the domestic sparrow was investigated with the light and electron microscopes and a step by step classification is proposed. Three cell populations corresponding to early, mid and late spermatids were easily divided according to their positions in the seminiferous epithelium. In addition to this initial separation, six steps were recognized, based on nuclear morphology and the degree of chromatin condensation, in association to their acrosomal and flagellar development. Early spermiogenesis is the period previous to chromatin condensation. The first step can be recognized by the extending flagellum and the second by the pro-acrosome development in contact with the nucleus. During the third or intermediate step, chromatin condenses and the cell becomes polarized with the pro-acrosomic vesicle and the tail occupying opposite sides of the nucleus. Late spermiogenesis, including steps IV-VI, is marked by complete chromatin condensation. The final cellular modifications lead to the formation of a spiraled spermatozoon. This shape is due to the twisting of the acrosome and nucleus, as well as the helical arrangement of mitochondria around the axoneme along most of the flagellum, making an exceptionally long middle piece.

Acrosome↗

PubMed1997

Season and migration alters the corticosterone response to capture and handling in an Arctic migrant, the white-crowned sparrow (Zonotrichia leucophrys gambelii).

The Gambel's race of white-crowned sparrow (Zonotrichia leucophrys gambelii) migrates each year from their wintering grounds in the Southwestern United States to the Arctic to breed. Associated with this migration is a change in both the nonstressed and the stress-induced levels of circulating plasma corticosterone. Birds were captured at two sites on their wintering grounds (New Mexico and Arizona). Although stress-induced corticosterone levels were elevated at each site compared to nonstressed levels, there were no differences between wintering sites. These were also similar to levels in birds caught in Washington state during fall migration. In contrast, nonstressed corticosterone values were greatly elevated in birds on their breeding grounds in Alaska and similar to stress-induced levels in wintering birds. Corticosterone levels rose even further in response to the stress of capture and handling in breeding birds. These augmented corticosterone levels during breeding were not associated with weather. Both nonstressed and stress-induced corticosterone levels were similar in birds caught on their breeding grounds on two different years, one with temperatures during mid-May of approximately 0 degree C during a snow storm and the other with temperatures in the mid-20s. These results suggest that seasonal physiological changes, and not local conditions, underlie seasonal changes in corticosterone levels. Furthermore, birds caught in Washington state during spring migration had intermediate levels of both nonstressed and stress-induced corticosterone. Corticosterone release may function differently during spring and fall migrations.

Adipose Tissue↗

PubMed1994

Selection against inbred song sparrows during a natural population bottleneck.

The genetic and demographic consequences of population subdivision have received considerable attention from conservation biologists. In particular, losses of genetic variability and reduced viability and fecundity due to inbreeding (inbreeding depression) are of concern. Studies of domestic, laboratory and zoo populations have shown inbreeding depression in a variety of traits related to fitness. Consequently, inbreeding depression is widely accepted as a fact. Recently, however, the relative impact of inbreeding on the viability of natural populations has been questioned. Work on the cheetah (Acinonyx jubatus), for example, has emphasized the overwhelming importance of environmental factors on mortality in the wild. Here we report that song sparrows (Melospiza melodia) that survived a severe population bottleneck were a non-random subset of the pre-crash population with respect to inbreeding, and that natural selection favoured outbred individuals. Thus, inbreeding depression was expressed in the face of an environmental challenge. Such challenges are also likely to be faced by inbred populations of endangered species. We suggest that environmental and genetic effects on survival may interact and, as a consequence, that their effects on individuals and populations should not be considered independently.

Animals↗

PubMed2003

Ancestral polymorphisms in genetic markers obscure detection of evolutionarily distinct populations in the endangered Florida grasshopper sparrow (Ammodramus savannarum floridanus).

Genetic analyses of bird subspecies designated as conservation units can address whether they represent units with independent evolutionary histories and provide insights into the evolutionary processes that determine the degree to which they are genetically distinct. Here we use mitochondrial DNA control region sequence and six microsatellite DNA loci to examine phylogeographical structure and genetic differentiation among five North American grasshopper sparrow (Ammodramus savannarum) populations representing three subspecies, including a population of the endangered Florida subspecies (A. s. floridanus). This federally listed taxon is of particular interest because it differs phenotypically from other subspecies in plumage and behaviour and has also undergone a drastic decline in population size over the past century. Despite this designation, we observed no phylogeographical structure among populations in either marker: mtDNA haplotypes and microsatellite genotypes from floridanus samples did not form clades that were phylogenetically distinct from variants found in other subspecies. However, there was low but significant differentiation between Florida and all other populations combined in both mtDNA (FST = 0.069) and in one measure of microsatellite differentiation (theta = 0.016), while the non-Florida populations were not different from each other. Based on analyses of mtDNA variation using a coalescent-based model, the effective sizes of these populations are large (approximately 80,000 females) and they have only recently diverged from each other (< 26,000 ybp). These populations are probably far from genetic equilibrium and therefore the lack of phylogenetic distinctiveness of the floridanus subspecies and minimal genetic differentiation is due most probably to retained ancestral polymorphism. Finally, levels of variation in Florida were similar to other populations supporting the idea that the drastic reduction in population size which has occurred within the last 100 years has not yet had an impact on levels of variation in floridanus. We argue that despite the lack of phylogenetic distinctiveness of floridanus genotypes the observed genetic differentiation and previously documented phenotypic differences justify continued designation of this subspecies as a protected population segment.

Animals↗

PubMed1984

[Initial division of Isospora sporozoites from a sparrow in cell culture].

The study of the sparrow Isospora in cell culture has demonstrated that during the extra-intestine life cycle, sporozoites undergo a primary division, resulting into two similar elements, whereas, in plain intra-intestinal cycle, the sporozoite is straightforwardly transformed into the first generation schizont.

Animals↗