Comparing line transect and Indian White-eye mobbing call playback for detecting forest birds in subtropical Yunnan

Acoustic signal complexity varies widely in animals, from single notes to highly sophisticated vocal displays. In birds, vocal complexity can evolve as an honest signal of individual quality driven by sexual selection. However, this hypothesis is rarely explored in conjunction with alternative drivers, including competition for ecological resources (social selection) and intra-group communication, both of which may favour increased signal complexity. Using Bayesian phylogenetic models, we test whether these alternative mechanisms predict the complexity of innate songs in 1288 species of suboscine passerine birds, while accounting for ecological constraints on sound production, transmission and detection. We found that overall song complexity was reduced by sexual selection (estimated from mating systems) and declined with body size and vegetation density. Conversely, note count and song length increased in territorial species, particularly those using song to defend year-round territories during the non-breeding season. These findings challenge the common assumption that sexual selection is the main driver of increased signal complexity and highlight the role of social selection via territorial competition as a factor increasing the temporal complexity of songs. Our results suggest that signal complexity depends on social, cultural and ecological contexts, reflecting a combination of multiple inter-related drivers and constraints.

Seasonal estrus limits sheep farming efficiency, making enhanced reproductive capacity and year-round estrus crucial for efficient breeding. GRM1 could modulates neuronal signals and stimulates neuron excitability. Our preliminary transcriptomic analysis of hypothalamic tissues from Kazakh ewes during nonbreeding season anestrus and nonbreeding season nutritionally induced estrus strongly suggested that GRM1 is a candidate gene that regulates estrus. The role of GRM1 in sheep estrus remains to be investigated. GRM1 expression was measured in hypothalamic tissues of Kazakh sheep during nonbreeding anestrus and nutritionally induced estrus via qPCR and immunohistochemistry. GRM1’s regulatory role in GnRH secretion and gene expression was studied in hypothalamic neurons via overexpression and RNAi. GnRH secretion changes were quantified by ELISA. GRM1 mRNA expression was significantly increased in the hypothalamus of estrous Kazakh sheep, as confirmed by immunohistochemical staining. The results of hypothalamic neuron experiments revealed that the expression of GRM1 was significantly upregulated after overexpression, which affected the expression of GnAQ, ITPR1, PLCB1 and PRKCB and ultimately promoted the secretion of GnRH. The expression of GnRH decreased after the interference in GRM1 expression. GRM1 modulates the secretion of GnRH in the hypothalamic nerve cells of Kazakh sheep through the glutamatergic synapse–calcium signaling pathway.

The field evaluation of the diagnostic performance of a commercial pregnancy-associated glycoprotein-based lateral flow assay for early pregnancy detection in ewes.

Summer underwater vocalizations of male Atlantic walruses Odobenus rosmarus rosmarus near their terrestrial haul-out site.

Vocalizations and sexual behavior from sexually active male goats stimulate testosterone secretion in quiescent bucks during the non-breeding season.

ABSTRACT The replacement of native temperate forests by exotic tree plantations is widespread in southern South America, yet its functional consequences for forest birds remain insufficiently understood. Because population density alone may not reliably indicate habitat quality, we evaluated whether substitution by mature Pinus radiata plantations alters foraging niche attributes of forest birds in south-central Chile. We compared bird densities, microhabitat use, foraging manoeuvres, and multidimensional niche overlap between native forest fragments and adjacent pine plantations during breeding and non-breeding seasons. Bird densities were generally lower in pine plantations, and several forest specialists were absent from this habitat. Mean foraging height showed no consistent habitat effect once species identity and temporal variation were accounted for. However, plantations were characterised by reduced foliage volume in lower strata, and foraging observations were disproportionately associated with native understory vegetation within plantations. For focal species with sufficient observations, multidimensional niche analyses revealed habitat-specific shifts in microhabitat use and, for one species pair, greater convergence in niche space in plantations relative to native forests. These patterns were accompanied by changes in the frequency of certain foraging manoeuvres. Our results indicate that habitat substitution by pine plantations modifies microhabitat use and niche relationships among forest birds, consistent with reduced structural complexity relative to native forests. Although some species exhibited behavioural flexibility, plantations did not support the full assemblage of forest specialists. Integrating behavioural niche attributes with density measures provides an informative assessment of habitat substitution effects in temperate Neotropical forest landscapes.

Within-individual consistency and between-individual variation in migratory and foraging behaviour have been observed in many species, including seabirds. Migratory differences among individuals within species have been linked to factors such as age, sex and animal personality, and may have fitness consequences. Therefore, we aimed to investigate individual consistency in distribution (i.e. location, distance from colony), foraging dive depth and dietary metrics for razorbills Alca torda during non-breeding seasons across years and whether these behaviours were related to a personality trait. Between 2017 and 2023, we deployed light-level geolocator (global location sensor, GLS) and combination geolocator temperature-depth recorder (GLS/TDR) tags on personality-tested razorbills (docile-aggressive continuum) during chick-rearing in coastal Newfoundland, Canada, and collected feathers (head, belly, secondary) to quantify stable isotope ratios of nitrogen (δ 15 N) as a proxy of trophic level. Razorbills displayed high repeatability ( R ) in their non-breeding locations and the distances travelled north ( R = 0.592) and south ( R = 0.564) from the colony. Razorbills also displayed low but significant repeatability in dive depth ( R = 0.133) and δ 15 N values ( R = 0.128). However, these metrics were not related to docility. Overall, the small but consistent differences in non-breeding location and foraging behaviour among individuals suggest that environmental conditions causing negative fitness consequences may be experienced by certain subsets of the population, thereby minimising the impacts of localised threats at the population-level. Although relationships between our measured personality trait (docility) and non-breeding behaviours were not observed, we suggest future studies investigate personality to understand the between-individual variation shown in a growing number of studies.

Little is known about the Sierra Nevada red fox (Vulpes vulpes necator; SNRF), a montane subspecies of red fox. The SNRF is a habitat specialist putatively limited to sky islands of alpine and subalpine meadows and parklands in the Cascades of Oregon and California and the Sierra Nevada of California. Populations in California have experienced substantial range contractions for unknown reasons in recent decades, complicating research and management, whereas populations in Oregon are more widespread, thereby allowing for accumulation of basic knowledge with conservation and management benefits. We collected data on radiomarked SNRF in Oregon during 2016-2020. Using a biased random bridge approach, SNRF showed patterns of larger areas used during the breeding (e.g., 95% utilization distribution, x̄ = 138.3 km2; n = 10) versus nonbreeding (x̄ = 79.5 km2; n = 12) season. Based on selection ratios to assess second-order cover selection, SNRF most strongly selected for parkland and meadow (alpine and subalpine), woodland (alpine and subalpine), grassland (alpine and subalpine), forest (hemlock [Tsuga]-dominated), and rock (volcanic, other), regardless of season. For third-order selection, SNRF often strongly selected for developed land-cover types, potentially associated with anthropogenic food sources. The most common cause of mortality was potential predation (three of seven foxes), and mean annual survival probability was 0.69. Given that SNRF are generally limited to sensitive, linear-shaped alpine and subalpine areas primarily on federal lands, multi-agency coordination for management decisions is necessary to address or mitigate impacts from humans, including impacts from increasing levels of recreational use and development. Key Points Sierra Nevada red foxes monitored in the Oregon Cascades had relatively large home ranges. Sierra Nevada red foxes selected for alpine-subalpine cover (parkland, meadow, woodland, and grassland), hemlock forest, and rocky areas. At finer scales, Sierra Nevada red foxes selected for developed land-cover types, potentially associated with anthropogenic food sources.

Although the function of birdsong has been well studied in male songbirds, the function of female song is less well understood. This is partly due to a historical view of females occupying a passive role compared with males, which led to the neglect of female song. We examined the female song in Galápagos yellow warblers, Setophaga petechia aureola, and show for the first time that it is widespread in the form of solo songs as well as duets. We interrogated the seasonal patterns and functions of female song by carrying out simulated territory intrusions using playbacks of male, female or duet songs during breeding and nonbreeding seasons and conducted a territory retention survey for over a year. We measured the association between aggressive response and singing behaviour, sex-specific patterns of response and territory retention across years. Females sang mostly during the nonbreeding season and predominantly in male-led duets. Although females were strongly aggressive towards female song playback, they gave the weakest singing response to it. There was no association between female aggressive behaviour and song output in response to a simulated intruder. Moreover, the probability of territory retention across years was not explained by song output or aggression in response to intruders, though evidence for this was weak due to the small sample size. We suggest that female song in this year-round resident island system does not function for signalling aggression in territory defence or intrasexual competition but may have other functions.

Abstract Conserving migratory birds requires a detailed understanding of their full annual cycle, including nonbreeding distributions, migratory pathways, migratory phenology, and patterns of migratory connectivity. This information could be particularly important for managing Limnothlypis swainsonii (Swainson’s Warbler), a Nearctic–Neotropical migrant of conservation concern. We tracked L. swainsonii from across their breeding distribution in the southeastern U.S. to identify migration routes and nonbreeding locations. In addition to traditional light-level geolocators, we used barometric pressure data collected by multisensor geolocators (pressure tags), which we combined with a global weather reanalysis and a movement model (GeoPressureR) to estimate precise, continuous locations, and collect previously unavailable flight behavior data. We deployed 43 pressure tags and 43 light-level geolocators on breeding male L. swainsonii across 6 states in 2021. We recaptured 31 (36%) tagged individuals in 2022, with 26 tags used for analysis. Light-level geolocators (n = 12) experienced chronic shading, resulting in broad nonbreeding estimates and little information during migration. Pressure tags (n = 14), however, provided accurate nonbreeding estimates (∼10–40 km) and all stopover regions. We found a longitudinal divide in nonbreeding distributions: western breeders of the Mississippi Valley and Missouri Ozarks migrated across the Gulf of Mexico to spend the nonbreeding season in the Yucatan Peninsula; eastern breeders from the Appalachians and Atlantic Coastal Plains migrated to Cuba and the Bahamas, with en route stops in Florida and Georgia. Pressure tags also revealed precise details of migratory movements, including phenology, flight durations and altitudes. Most notably, individuals traveled significantly faster and spent less time at stopovers during fall migration than in spring, antithetical to current understanding. Migratory pathways and wintering grounds of L. swainsonii suggest eastern and western breeding populations experience different environmental conditions, ecological and anthropogenic barriers, and habitat quality during migration.

Interlinked population dynamic and evolutionary responses to spatial and seasonal environmental variation, stemming from interactions and feedbacks among phenotypic variation, genetic variation, selection and demography, could generate complex eco-evolutionary dynamics that span temporal and spatial scales. Partially migratory metapopulations (PMMPs), featuring sequential seasonal sympatry and allopatry of different sets of resident and seasonally migrant individuals, have clear potential for such eco-evolutionary outcomes. This is because ongoing evolution of reversible seasonal migration affects spatio-seasonal population dynamics and densities, which could in turn shape forms and magnitudes of selection on migration, causing feedbacks on evolution. However, key environmental and genetic conditions that maintain migratory polymorphisms, and resulting eco-evolutionary dynamics of PMMPs given stochastic environmental variation and strong spatially restricted seasonal perturbations, have not been characterized. We built a general individual-based model that tracks eco-evolutionary dynamics in PMMPs inhabiting spatially structured and seasonally varying landscapes, with seasonal migration formulated as a quantitative genetic threshold trait. Simulations showed that such genetic architectures and landscape structures, which are common in nature, readily produce stable partially migratory systems given diverse regimes of environmental variation. Partial migration is maintained whenever sites differ in non-breeding season suitability, defined as variation in density-dependence, causing 'ideal free' non-breeding distributions where residents and migrants occur with frequencies generating similar survival probabilities. Further, bet-hedging can cause stable partial migration without any fixed differences in non-breeding season density-dependence among sites and even without density-dependence at all, given sufficiently large stochastic environmental fluctuations among sites and years. Importantly, major local non-breeding season mortality events, as could result from extreme climatic events, generate eco-evolutionary dynamics that ripple out to affect breeding and non-breeding season space use of subpopulations throughout the PMMP, on both short and longer timeframes. These effects result from spatially divergent selection on the occurrence and destination of migration. Our model thus shows how changing partial seasonal migration acts as a key mediator of eco-evolutionary dynamics in (meta)populations occupying spatially and seasonally varying environments. It thereby initiates new steps towards predicting responses of natural partially migratory populations to ongoing changes in spatio-seasonal patterns of environmental variation.

This case report presents the therapeutic response to TAK‑683, a long-acting kisspeptin analog, in the treatment of a follicular cyst that developed following a conventional estrus synchronization protocol in a goat during the non-breeding season. A two-year-old lactating Aleppo goat showing persistent nymphomaniac behaviour after estrus synchronization was diagnosed with an ovarian follicular cyst by transrectal ultrasonography. The left ovary contained a 17.7 mm thin-walled anechoic cyst, while serum estradiol (14.5 pg/mL) was elevated and progesterone (1.6 ng/mL) was low. The goat was treated with a single subcutaneous dose of the kisspeptin analog TAK-683 (5 µg, Day 0). Therapeutic efficacy was assessed by monitoring ovarian ultrasonography and serum hormones on Days 3, 10, 13, and 17. Following treatment, the cyst underwent luteinization accompanied by a rise in progesterone (peak 6.4 ng/mL) and a decline in estradiol to basal levels, alongside normalization of behaviour. Color Doppler assessment confirmed progressive luteal development and vascularization, followed by natural luteolysis on Day 17 and resumption of follicular activity. In conclusion, this is the first clinical report demonstrating the successful use of TAK‑683 in resolving a follicular cyst in goats. These findings suggest that TAK‑683, beyond its ovulation-inducing role, may offer a promising therapeutic alternative to GnRH agonists for managing reproductive pathologies in veterinary gynaecology. First report of follicular cyst treatment in a goat with TAK-683. 5 µg of TAK-683 induced luteinization and normalized hormone levels. TAK-683 may offer an alternative to GnRH agonists in follicular cyst treatment.

Diet may be fundamental to the extensive paternal care and reduced maternal care seen in bat-eared foxes (Otocyon megalotis). This termite-specialist would struggle to increase its energy intake by hunting large prey or provisioning such items to mates or pups. Consequently, lactating, physiologically challenged females need to invest more time in foraging, while males spend time with pups. However, there is little empirical evidence of the impacts of parental care on foraging behavior and stress-related hormone levels in free-living bat-eared foxes. We studied foraging behavior in 20 wild bat-eared foxes for 2 years, investigating how foraging behavior and fecal glucocorticoid metabolite (fGCM) levels varied with austral season in the study population. Thereafter, we evaluated how parental status may affect foraging rates, food sizes consumed, and fGCM levels as a proxy for physiological stress. We examined these changes in parents (n = 3) and non-parents (n = 17) as seasonal “activity” changed—that is, breeding season (pregnant phase), denning season (pup-rearing and guarding phase), and non-breeding season (independent adult phase). Small item consumption patterns mirrored overall foraging rates, which were lowest for all foxes in winter. Males increased foraging rates in spring, while all individuals ate more large items in summer. Mean fGCM levels in the population (0.41 µg g−1 organic content) were not affected by sex or austral season, but changed with seasonal activities, for parents in particular: parents had significantly lower fGCM levels in the breeding season. This may reflect reduced stress in these foxes, who successfully paired and increased their within-family socialization during the breeding season. Our findings suggest that behavioral adaptations, including foraging adaptations, are sufficient for bat-eared foxes to meet the physiological challenges of parenting. This is the first study to start unravelling the relationship between foraging rates, parenting behavior, and stress-related hormone levels in the Bat-eared Fox.

Male-Specific Territoriality and Use of Specific Calls during the Non-Breeding Season in the Polygynous Eurasian Wren Troglodytes troglodytes

Spatial pattern and conservation challenges of migratory waterbirds in Asian flyways

Seasonal variation of prostatic steroid hormone synthesis capacity in wild ground squirrels (Spermophilus dauricus).

Intraepididymal platelet-rich plasma improves semen cryoresistance via antioxidant, lipid and molecular modulation during the non-breeding season in rams.

Cover photo: Common Loon Gavia immer with prey. Photo: Torborg Berge. Diet and aspects of feeding behaviour of Yellow-billed Loons Gavia adamsii and Common Loons G. immer were compared during the non-breeding season in coastal Norway. Stomach contents from 14 Common Loons and 13 Yellow-billed Loons showed that fishes constituted the main prey of both species. However, saithe Pollachius virens constituted a major component of the diet of the Yellow-billed Loon, whereas wrasses (Labridae), flatfish (Pleuronectidae), and sandeel Ammodytes tobianus were important prey for Common Loons. Common Loons also frequently included crustaceans and sometimes molluscs in their diet. We tested the hypothesis that the Yellow-billed Loon, with its more upturned bill, feed more on bottom-living prey than the Common Loon. Contrary to the hypothesis, stomach contents indicated that more bottom-living prey were taken by Common Loons, and Yellow-billed Loons seemed to prey more on pelagic fish. A difference in prey selection was consistent with field observations that Yellow-billed Loons often fed in water judged too deep for bottom-feeding, social groups were often synchronized when feeding, and their stomach contents contained only a few gastroliths compared to Common Loons. Species differences in number of gastroliths indicate that Yellow-billed Loons are feeding on softer food such as pelagic fish, whereas Common Loons are feeding on crustaceans and the more armoured and spiny fishes occurring in bottom habitats.

This study aimed to evaluate the efficacy of estrus synchronization protocols in goats and to identify the most cost-effective regimen for intensive farming. The protocols assessed used progesterone (P4) sponges or controlled internal drug release (CIDR) devices, with supplemented with pregnant mare serum gonadotropin (PMSG) and prostaglandin (PG), for inducing estrus and pregnancy in goats, and to identify the most cost-effective regimen for intensive farming. During both breeding and non-breeding seasons, does were assigned totreatments: Group I (P4 sponge + PMSG), Group II (P4 sponge + PMSG + PG), and Group III (CIDR + PMSG + PG). We measured estrus response after device removal and pregnancy rates after artificial insemination (AI) were evaluated and analyzed serum hormone dynamics. Additionally, medication costs were calculated for each protocol. For the most effective protocol, we also determined ovulation timing, performed laparoscopic-assisted AI. Estrus onset occurred earlier in Groups II and III than in Group I during both trial seasons. Nevertheless, overall estrus and pregnancy rates did not differ significantly among the groups (P > 0.05), with Group II exhibiting the lowest pregnancy rate. Medication cost per does and per pregnancy were lowest for Group I. Under the Group I protocol, ovulation occurred at 32 h after estrus onset, and laparoscopic-assisted AI yielded a significantly higher pregnancy rate with fresh semen than with chilled semen (P < 0.05). Serum estradiol (E2) concentration at estrus onset was significantly higher in Group I than in Group II (P < 0.05), and luteinizing hormone (LH) levels at estrus onset and ovulation were significantly higher in Groups I and III than in Group II (P < 0.05). Serum P4, LH, and E2 profiles during the estrous cycle followed similar patterns across all groups. In conclusion, there was no significant difference in pregnancy rates between the three estrus synchronization protocols. However, Protocol I demonstrated the lowest per doe and per pregnancy medication costs. Based on cost-effectiveness considerations, the P4 sponge + PMSG protocol is recommended for use in intensive goat production systems.