Search Results (61)

Information on the breeding of the Pinto’s Spinetail (Synallaxis infuscata), an endangered Brazilian Furnariid, is scarce. This study aims to complement it, by looking at nest and clutch parameters, breeding period, and nest success. Once nests were found, they were closely monitored from a hide. Between 1986 and 2018, 33 nests were found in the Pedra Talhada Forest near Quebrangulo. Nests were found year-round, except in middle of the dry season. Nests were of the closed/retort type, weighing 552.1 g, and measuring 37.6 × 28.8 cm, with a side arm of 30.6 × 4.9 cm, on average. The clutch size averaged 2.10 eggs, which measured 22.3 × 17.2 mm and weighed 3.2 g. They were white and had an oval to pointed-oval shape. Mean incubation period was 21.5 days and mean nestling period 14.71 days. The apparent nest success was 27.3%, while Mayfield’s was 21.8%. Predation was the main cause of nest failure, accounting for 81% of cases. The breeding data we collected on S. infuscata falls within the range of observations of a comprehensive analysis on other Synallaxis species. This breeding information is important for conservation, as rates of nest loss are a key factor in evaluating population viability. Full article

Nest architecture and surrounding habitat features can strongly influence the reproductive success of cavity-nesting birds; however, quantitative data from natural environments remain limited. We examined how nest structure and surrounding habitat features correlate with reproduction in the small bee-eater (Merops orientalis). A total of 38 natural nests were monitored during the breeding season. The Conway–Maxwell–Poisson model showed that cavity depth was a significant positive predictor of clutch size (β = 0.46 ± 0.22 SE, p = 0.036), whereas entrance diameter and nest height were not significantly related. Principal component analysis (PCA) of standardized cavity dimensions (cavity depth, entrance diameter, and nest height) showed that nest height (captured by PC2) was strongly associated with higher breeding success (OR = 0.002, p = 0.021), whereas overall cavity size (PC1) had a weaker, marginally positive correlation (OR = 3.87, p = 0.09). Habitat distance variables showed only weak, non-significant trends after accounting for multicollinearity. Nest structural traits explained more variation in reproductive performance than landscape variables (pseudo-R² = 0.80 for clutch size; 0.59 for breeding success). Field monitoring of 38 nests showed a mean clutch size of 3.9 eggs, an overall hatching success of 77.5%, and a fledging success of 51.2%, yielding a 37.1% breeding success. Our results highlight the importance of conserving sandy streambanks and mitigating human disturbance in proximity to active nests to conserve breeding success in small bee-eaters. As these findings were based on one site and a single breeding season, broader generalizations will require replication across additional years and locations. Full article

The distribution of individual body sizes within a population can have substantial impacts on recovery estimates for endangered species. Recent studies have observed a reduction in the size of nesting sea turtles with potential implications for fecundity. To investigate the size of reproductive individuals and subsequent impacts on hatchling production for loggerhead turtles in northwest Florida, we evaluated a seven-year dataset from St. George Island, Florida, USA—the dominant nesting site in this region. Morphometric measurements and GPS locations were collected during nighttime surveys, whereas nest disturbances and hatchling production were reported from morning surveys. Mean minimum curved carapace length (CCL_min) was 94.3 cm ± 5.7 cm SD (range: 80.2–109.1 cm). Out of 232 individuals, 9.1% fell below the 87 cm CCL_min threshold currently adopted by U.S. agencies as the minimum size at maturity. For each 1 cm increase in CCL_min, an increase by 1 egg was observed in clutch size, and wash-out rates increased by 0.52%. Though the largest turtles laid the largest clutches, these nests also had a greater probability of wave wash-out, potentially moderating overall hatchling production from these individuals. These results highlight size-mediated factors related to fecundity—important elements for demographic modeling and management decisions. Full article

Intraspecific brood parasitism (IBP), where one female lays eggs in another’s nest, is considered rare in raptors, including typically monogamous and solitary or semi-colonial falcons. The Lesser Kestrel (Falco naumanni) is a colonial falcon with a usual clutch size of one to five eggs, yet two independent cases of anomalously large clutches consistent with suspected IBP are described from long-term studies in Greece and Israel. In central Greece (Armenio; 39°29′ N, 22°41′ E), a nest box colony monitored since 1998 produced a clutch of eight unhatched eggs in 2017; egg volumes formed two statistically distinct groups (V₁ = 850.74 ± 27.72 vs. V₂ = 926.78 ± 18.87 mm³; t = 4.146, p = 0.006), suggestive of contributions from two females. In Israel (Alona District; 32°35′ N, 35°05′ E), a nest under an asbestos roof contained a mixed clutch of eight eggs laid over two seasons (2003–2004), with four new eggs added to four unhatched eggs from the previous year; only one egg hatched and the chick was subsequently predated by a Little Owl (Athene noctua). Given the species’ typical clutch size and the occurrence of double clutches, these cases are interpreted as rare instances of parasitic egg-laying. Their extreme rarity—only one event over more than 20 years of monitoring ~120 pairs annually in Greece—underscores how uncommon IBP appears to be in Lesser Kestrels and how easily such events may be overlooked without intensive, long-term monitoring. The results emphasize the need to combine detailed field observations with molecular parentage analyses, quantify IBP frequency, and clarify the ecological and evolutionary relevance of alternative reproductive strategies in this and other colonial raptors. Full article

The tomato hind grouper (Cephalopholis sonnerati) is an emerging aquaculture species, with significant commercial value and promising farming potential. To advance the theoretical framework for artificial breeding, this study systematically investigated the embryogenesis, early larval morphology, growth patterns, and heritable traits of the species. The results indicated fertilization and hatching rates of 88.67 ± 3.93% and 79.67 ± 7.55%, respectively, with an average egg diameter of 0.87 ± 0.02 mm. Hatching occurred 22:55 h after fertilization at 24.80 ± 0.70 °C, corresponding to 568.42 degree-hours, and the newly hatched larvae measured 2.09 ± 0.12 mm in total length. Interestingly, as the fish grows, the color of its head patches shifts from yellow to red, providing a visible trait that can be used for early growth screening. After 15 months of graded rearing, marked growth disparities were observed among individuals originating from the same clutch, with the fast-growing group weighing 457.12 ± 58.68 g, which was 2.9 times greater than that of the slow-growing group. These findings underscore the potential of C. sonnerati as a valuable aquaculture species. Future efforts should prioritize enhanced broodstock selection and the development of fast-growing germplasm to increase its cultivation potential. Full article

The Yellow-spotted Bell Frog, Ranoidea castanea is a critically endangered species, native to the tablelands of New South Wales, Australia. It was rediscovered in 2009, after it had seemingly disappeared thirty years earlier. Upon rediscovery, a conservation breeding program was established at Taronga Zoo in Sydney, Australia, to secure an insurance population of the species. This paper describes the ex situ management and first successful captive breeding of this species, documents its life history data, and provides valuable learning that may benefit other conservation breeding programs. Although initial breeding attempts were unsuccessful whilst founding animals were housed indoors or in small outdoor enclosures, success was achieved between 2017 and 2019, once frogs were moved into a large outdoor enclosure (five clutches in three seasons). The attempted breeding of F1 individuals in an indoor dedicated facility in 2024 had greater success, with 60% of paired females laying eggs (six clutches in one season). Breeding behaviour occurred primarily between October and December, with clutches of unpigmented eggs laid amongst submergent vegetation from late October to mid-November. Overall, the program has resulted in the production of 2162 juvenile frogs for release, in addition to the retention of over 100 frogs for the insurance population. Herein, we provide important life history data for our study species and a framework for conservationists to propagate this species in an ex situ environment. We also highlight other key considerations, such as i) the importance of quickly establishing conservation breeding programs for threatened species and not assuming a targeted species will breed as readily as an analogue species, and ii) underscore the importance of undertaking baseline disease screening in the in situ environment. Full article

Gynogenesis is a reproductive mode where offspring inherit exclusively maternal chromosomes. Gynogenetic development in fish may be induced intentionally by activating eggs with the UV-irradiated, inactive spermatozoa. In the meiotic variant of gynogenesis, the resultant haploid gynogenetic zygote is then exposed to a physical shock to inhibit the release of the 2nd polar body and to reconstitute the diploid state of the embryo. Here, meiotic gynogenesis was induced in the rainbow trout eggs from different clutches to find any differences in terms of gene expression and antioxidant enzyme activity between eggs with high and low ability for gynogenetic development. The survival rates of the gynogenotes after hatching from the eggs originating from five females varied from 16.6 ± 4.3% to 53.8 ± 9.8%. Biochemical and molecular examination revealed that eggs with higher developmental potential for meiotic gynogenesis exhibited significantly greater glutathione peroxidase (GPx) activity than eggs with lower efficiency of gynogenesis. Moreover, eggs exhibiting the highest ability for gynogenetic development showed increased transcription of the keratin 8 gene and decreased abundance of keratin 18 and tubulin β mRNA transcripts. Since keratins protect oocytes from physical stress after ovulation, the high abundance of keratin 8 in the rainbow trout eggs may increase their resilience to the physical shock applied for the zygote diploidization during gynogenesis. On the other hand, a low level of tubulin-building microtubules may increase the efficiency of high hydrostatic pressure (HHP) shock used for diploidization of the gynogenetic zygotes. Full article

To accelerate breeding progress for egg production traits in Lindian chickens, the genetic parameters for egg production and clutch-related traits in Lindian chickens were evaluated in the present study. Data regarding the age at first egg (AFE), egg number (EN), average clutch length (ACL), and average pause length (APL) were collected from two generations of Lindian chickens based on individual egg production records at 32 weeks of age (32–wk), 43–wk, and 52–wk. The results showed that the AFE of Lindian chickens was 179.3 d of age, with a heritability of 0.35. The heritability was 0.26 for EN32, 0.28 for EN43, and 0.34 for EN52. ACL showed moderate-to-high heritability (h² = 0.3–0.54), but APL traits showed low heritability (h² = 0.09–0.14). There were high positive genetic and phenotypic correlations for EN in the three periods from the start of laying up to 32–wk, 43–wk, and 52–wk. EN had high negative genetic correlations with AFE (r_G = −0.47–−0.80) and high positive genetic correlations with ACL (r_G = 0.45–0.81). The correlation between EN and APL was positive for 32–wk and 43–wk, but negative for 52–wk. These results indicated that the egg production of Lindian chickens could be improved by the selection of AFE, early EN, and ACL. Full article

Laying additional clutches of eggs, or renesting, can provide birds with more opportunities to breed each season, ultimately increasing reproductive potential. This is important for long-lived species like cranes, that produce relatively few offspring annually. The reintroduced Eastern Migratory Population (EMP) of endangered Whooping Cranes relies on releases of captive-reared juveniles for population growth. Using long-term nest monitoring data, we assessed the renesting propensity of 105 unique pairs of Whooping Cranes during 2005–2024 (n = 359). We used a two-tiered analysis of binomial generalized linear mixed-effects models to evaluate the effects of 15 individual covariates, related to parental age or experience, nest management geography, or chronology. Overall, 37.3% of pairs renested following failed first nesting attempts. We documented higher renesting rates from breeding females that were older or had more years of nesting experience (37.1% increase for each unit increase in female age), pairs outside of the regions in which captive-reared cranes were released (264.0% increase in “other” region compared to Necedah), or that had nests fail earlier in the season (10.1% decline for each day later in the season a first nest failed). Additionally, when eggs were collected from first nests as a part of nest management, pairs were more likely to renest (69.4% renested) than if their nest failed naturally (27.3% renested). Low rates of natural reproduction limit growth rates in the EMP, so understanding effects of management actions and limitations on breeding are important conservation tools which can be applied to other endangered species. Full article

Secondary cavity-nesting birds can utilize artificial nest boxes provided by humans for breeding, making nest boxes important approaches for attracting birds. Artificial nest boxes are therefore widely used in fields such as ornithological research and avian diversity conservation. Under natural conditions, the location of nests often affects the reproductive success of birds. Therefore, understanding the impact of nest box hanging positions on the breeding success of secondary cavity-nesting birds is of great significance for guiding the placement of artificial nest boxes. In this study, we explored the potential factors, including nest-box location, that affect the reproductive success of the russet sparrow (Passer cinnamomeus) by monitoring the nest-site characteristics and reproductive parameters such as clutch size and brood size of those breeding in artificial nest boxes near Dongzhai National Nature Reserve, Henan, China, from April to July 2024. Russet sparrow nesting in boxes on coniferous trees and utility poles showed no significant differences in clutch size, hatching rate, brood size, pre-laying nest-abandonment rate, and whether the breeding was ultimately successful. Nests with earlier egg-laying dates had larger clutch sizes, higher hatching rates, and greater brood sizes. However, the number of fledglings and fledging success were not affected by laying date, and fledging success was not affected by either the distance from the nest site to the nearest road, or the brood size. Both larger brood size and greater distance from the nearest road were associated with increased numbers of fledglings. Furthermore, russet sparrows nesting in boxes on coniferous trees produced significantly more fledglings and exhibited higher fledging success compared to those nesting on utility poles, suggesting that nest boxes’ hanging position may influence russet sparrow reproductive success. These findings not only supplement existing ecological data on russet sparrow reproduction in artificial nest boxes but also provide important insights for avian conservation practices, highlighting the necessity of fully considering hanging position when deploying artificial nest boxes for birds. Full article

Limited research exists on the breeding ecology of the black francolin (Francolinus francolinus) in northern Pakistan. This study assessed egg dimensions, clutch size, hatching, fledging, and overall breeding success across different habitats and nests (n = 25) at Totali Game Reserve, Buner. Generalized linear models (GLMs) were used to analyze the effects of nest site characteristics and nest traits on breeding parameters. Egg dimensions were consistent across sites whereas bush nests had slightly wider eggs. The average clutch size was 5.9 ± 1.7 eggs, with an average of 4.8 ± 1.0 hatchlings per nest. A total of 111 chicks fledged, averaging 4.4 ± 1.0 per nest, yielding an overall breeding success rate of 75.5%. Nests containing six eggs had higher hatching success (76.6%). GLMs results showed a significant positive relationship between clutch size and hatchling, while nest site and traits had no significant effects. However, fledgling success was positively influenced by hatchling numbers, with nests in wetland habitats yielding significantly more fledglings (4.6 ± 0.9) than those from dryland habitats (4.0 ± 1.2). These findings suggest Black Francolins prefer nesting in wetland areas in bushes, likely due to better protection and favorable conditions. Full article

The Sardinian grass snake, Natrix helvetica cetti, is an island-endemic subspecies with a restricted and highly fragmented distribution confined to Sardinia, Italy. Information on its reproductive biology and wild offspring remain scarce in the scientific literature. This present study reports the first recorded data on a clutch of eggs laid by a wild melanistic female N. h. cetti that exhibited lethargy when observed basking, prompting a brief period of health monitoring and screening for the presence of the pathogenic fungus Ophidiomyces ophidiicola (Oo). The clutch yielded nine hatchlings, for which phenotypic data are provided and compared with existing information on the Natrix natrix complex. Both the adult female and its offspring tested negative in the Oo screening. The body size of the adult grass snake, specifically its snout-to-vent length of 48.3 cm, is the smallest ever recorded for a gravid female N. helvetica. This may indicate that maturity is reached at particularly small sizes, a distinctive trait of this intriguing island subspecies, suggesting the need for further investigation. Full article

Diapause, a survival strategy utilized by many insects under severe environmental conditions, can generate costs that potentially affect post-diapause development and reproduction. The willow leaf beetle, Plagiodera versicolora, overwinters as an adult. This study investigated the cold hardiness-hardiness and energy utilization of female P. versicolora, and their impact on post-diapause reproductive fitness. The supercooling point exhibited seasonal temperature variation, with the lowest points occurring in January and February, coinciding with the relatively lower ambient temperatures. Lipid content demonstrated a pronounced decline at the onset of diapause (from November to December) and stabilized from December to March. Glycogen content also showed a sharp decrease from November to January, subsequently stabilizing at relatively constant levels. In addition, trehalose content increased significantly when temperatures dropped (from November to January) and then decreased as temperatures rose (from January to March). There were no significant differences in the time from pairing to successful mating for post-diapause females compared with non-diapause females. However, mating duration and the pre-oviposition period for post-diapause individuals relative to non-diapause individuals increased, coupled with a reduction in the oviposition period, total number of eggs, number of egg clutches, and number of eggs per clutch; however, most importantly, there was no notable change in egg-hatching success. These results suggest that the cold-hardiness strategy of P. versicolora falls within the freeze-avoidance category, with energy usage predominantly reliant on lipids and carbohydrates during diapause initiation. Our findings also highlight that, although post-diapause females are capable of nutrient replenishment, the energetic demands of diapause result in considerable negative impacts on post-diapause female reproductive fitness. Full article

Due to the limited number of field studies investigating associations between environmentally relevant per- and polyfluoroalkyl substances (PFAS) mixtures and reproductive impairment, there is uncertainty as to whether birds are affected by PFAS pollution, whether species differ in sensitivity to PFAS, and whether the observed reproductive impairment is caused by PFAS or rather due to other potential confounding variables. Therefore, we investigated PFAS concentrations in eggs and blood plasma of great tit (Parus major) and blue tit (Cyanistes caeruleus) nestlings near a PFAS hotspot in Belgium, reproductive impairment, and associations between the accumulated levels and nestling body condition. In total, 29 eggs and 22 blood plasma samples of great tit clutches, and 10 egg and 10 blood plasma samples of blue tit clutches, were collected. Despite more types of PFAS being detected in eggs compared to plasma, only minor differences in profiles were observed between species. On the other hand, tissue-specific differences were more pronounced and likely reflect a combination of maternal transfer and dietary exposure post-hatching. Despite the high concentrations detected in both species, limited reproductive impairment was observed. Our results support previous findings that great tits and blue tits may not be very susceptible to PFAS pollution and provide evidence that other factors, including ecological stoichiometry, may be more important in explaining inter-species variation in PFAS accumulation and reproductive impairment. Full article

The Rio Pescado stubfoot toad (Atelopus balios) is a critically endangered member of the struggling Atelopus genus which has been ravaged by the fungal pathogen Batrachochytridium dendrobatidis. Captive management of this species is crucial to improve survival outcomes in their native range in Ecuador. Here, we talk about reproductive successes with A. balios at The Dallas World Aquarium, which represents the first successful reproduction of this species outside of Ecuador. We document five clutches of eggs that were deposited in the adult breeding tank and the developmental rates of the offspring. We also provide observations on husbandry regimes that support the recovery of the females’ postdeposition along with observed time between reproductive events for females. We also document the habitat requirements of the adults of the species and the offspring with notes on feeding practices once toadlets emerge from the water. Documentation on the reproduction of Atelopus species is critical to understanding habitat preferences and cues needed to influence reproduction in the wild and thus give insights into the path of captive propagation in the conservation of the focal species. Full article