Mean Clutch Size Research Articles

Breeding biology of the Little Egret Egretta garzetta on the southern coast of the Bay of Biscay

ABSTRACT Capsule: Annual reproductive parameters of Little Egrets Egretta garzetta in an Atlantic coastal colony showed strong variation in a 20-year study, mainly due to extreme events. Aims: To describe the breeding biology of Little Egrets in the Bay of Biscay and compare it with that of the Mediterranean basin. Also, to explore relationships between breeding parameters and colony size with some climatic indicators. Methods: Phenology, number of nests, clutch size, number of hatchlings, brood size, and hatching and breeding success were recorded over 20 years. Results: Median laying date of 214 nests was 1 May (range: 1 April–25 June) and 54% of the clutches were laid in the second half of April and the first half of May. Over the 20-year study period mean clutch size of 270 nests was 4.0, mean number of hatchlings was 3.1, and mean brood size was 2.3. Hatching success ranged from 46.1% to 100% and breeding success from zero to 100%. Number of nests was negatively associated with clutch and brood size. The highest clutch size and lowest brood size were recorded at the beginning of the season. Significant relationships were found between the number of hatchlings and the rainfall during the pre-breeding season, and between brood size and the summer rainfall. Conclusions: Reproductive parameters showed significant variation over the study period, which highlights the importance of using long-term data sets. Breeding occurred one month later than in natural colonies of the Mediterranean basin. Negative relationships between the number of nests and clutch and brood size suggest some degree of density-dependent effects. Ranges of clutch size, number of hatchlings, and brood size were within those reported in Mediterranean populations. The effect of rainfall on reproductive parameters was weak. Extreme weather and predation events caused low rates of hatching and breeding success that affected the growth of the colony.

Nesting ecology of White-faced Ibis (Plegadis chihi) in Great Salt Lake, Utah

We studied the nesting ecology of White-faced Ibis (Plegadis chihi) at 3 sites within the Bear River Migratory Bird Refuge, Great Salt Lake, Utah, USA. Ibises built nests in small mounds (mean height = 14.4 ± 4.3 cm) above shallow water (mean depth = 12.0 ± 6.6 cm) located within patchy vegetation (mean percent vegetative cover = 17.2 ± 17.8% vegetative cover) with mean vegetation height of 31.7 ± 9.8 cm. White-faced Ibis typically laid a clutch of 3 or 4 eggs (mean clutch size = 3.08 ± 0.76) and initiated nests over a 50 d period between 24 April 2012 and 12 June 2012. Mean nest success was 38% (95% CI: 31–45%) and hatching success of eggs from successful nests was 76 ± 26%. Although most of the breeding parameters estimated for White-faced Ibis nesting in Utah were comparable to other populations in Oregon and Idaho (USA), nest success may now be lower than has been historically documented.

Female reproductive cycle of the snaked-eyed Lizard <em>Ophisops elegans</em> Ménétriés, 1832 (Reptilia: Lacertidae) from Lebanon

We studied the female reproductive cycle of a population of Ophisops elegans lizard from the herpetology collection of the Natural History Museum of the Lebanese University. Females collected during spring and summer showed vitellogenesis in their ovaries with oviposition occurring from May to July followed by a subsequent quiescent period. They produced up to two clutches. Mean clutch size was 3.2 ± 1, range 2-5 eggs. Clutch size was independent of female body size. The smallest female attaining sexual maturity had a snout vent length of 45 mm. Sexual maturity can be attained within one year of age. We found no significant difference in body size between female and male adult lizards. Seasonal variations in the reproductive activity of females were well synchronized with those of males.

Resultat av 20 års holkstudier – främst rörande svartvit flugsnappare Ficedula hypoleuca

Breeding activities in 133 nest-boxes of varying sizes, erected in mainly deciduous woods in Linderås, southeastern Sweden (57°58'N; 14°15'E), were recorded from 1986 to 2005. In total, 1,841 pairs representing 15 species bred in the boxes; mean occupancy was 75%. The Pied Flycatcher Ficedula hypoleuca was the most frequent species. Its population numbers showed no significant trend while its fluctuation pattern largely paralleled those of two contemporary Swedish studies. Dates of spring arrival and start of egg-laying varied independently without any trend. Mean clutch size was 6.32, equalling those obtained in other Swedish studies, even though the proportion of 6-egg clutches and mean number of fledglings (4.26) were significantly lower. Only 40% of the breeding attempts were entirely without losses, such as failed hatching (8% of 6,370 eggs), predation, or usurpation by other species. A total of 550 incubating females and 3,653 nestlings were ringed of which 12% and 0.3%, respectively, returned to the study area in the subsequent season. Of females that returned, 41% reappeared in the first and 48% in the second ensuing season.

Nest characteristics and breeding success of Black Kites (Milvus migrans migrans) in the High Plateau (Algeria)

The breeding ecology of the Black Kite Milvus migrans migrans in Algeria was first studied in 2014 and 2015 on Tarf Mountain in the semi-arid High Plateaus region. The nearest-neighbour nest distance was found to range from 130 to 550 m for colonial pairs and from 1,730 to 2,390 m for the solitary ones. All 12 monitored nests were placed on cliffs at different heights ranging from 149 to 155 m. The mean egg laying period was 15 days, and the mean clutch size was 2.83 ± 0.31 and 3 ± 00 eggs per nest in 2014 and 2015, respectively. The mean hatching success was 83% and that of fledging 75%. Only 2 nests were predated. Our results disagree with those of the previous studies that were carried out mainly in the Mediterranean basin and Asia, differing in such nest characteristics as the nearest - neighbour nest distance, cliff and nesting heights, egg laying period and hatching success. Otherwise, no consistent differences in clutch size and fledging success were revealed. Finally, we determined that Black Kites tend to build their nest on the eastern side of cliffs. However, our analysis showed no effect of nest placement on breeding parameters and success.

Nesting ecology and parental care of the Sabota Lark (Calendulauda sabota) in a savanna landscape in South Africa

We report on the breeding biology of the Sabota Lark (Calendulauda sabota), a widespread and common but poorly known species. We present the results of data collected at 57 nests over 2 breeding seasons (2011–2013). Breeding coincided with the peak of the wet season in the study area and the breeding season appeared to be shorter in the study area compared to the rest of the species' range. Only females were observed constructing nests and laying and incubating started before the nest was completed, a strategy to reduce the overall nesting time. Nest quality varied considerably, including in the presence or absence of a dome and an apron. The mean clutch size was 2.5 ± 0.5 with incubation commencing upon clutch completion, performed by the female only and lasting 12.3 ± 0.5 d. Mean nest attendance during incubation was 74% and there was a steady increase in the duration of incubation on-bouts with progression of the incubation period. The mean nestling period lasted 11.7 d with both parents delivering food and both sexes performing brooding duties, a seemingly unique feature in the mirafrid clade of larks. There was evidence of subtle sex-specific roles during the nestling period with females primarily being responsible for brooding and males mainly provisioning. Breeding success using Mayfield's estimator was 33% with predation being the main cause of nest failure. Given the relatively poor breeding success, replacement broods were common but repeat-brooding attempts in a single season were rare with only 2 records during the course of this study. Although many of the reproductive features of Sabota Lark were similar to those of other larks, there were some differences and some apparently unique features that contribute to our knowledge of the Alaudidae.

Multiple nesting attempts and long breeding seasons of Mimus gilvus (Aves: Mimidae) in southeastern Brazil

This study describes aspects of the life history of the Tropical MockingbirdMimusgilvus(Vieillot, 1808), including the breeding period, clutch size, nestlings and a list of plants used for nesting. Nests were monitored in an area of Restinga (sand-coastal plain) habitat in a protected area in southeastern Brazil. The data from 181 nests during five breeding seasons (2010-2014) showed that the Tropical Mockingbird has a long breeding season (26.1 ± 2.6 weeks) with up to two peaks of active nests from August to March. The breeding pairs made up to four nesting attempts in the same breeding season. The mean (± SD) clutch size was 2.4 ± 0.6 eggs (n = 169). The mean (± SD) incubation period was 14 ± 0.6 days, and the nestling remained in the nest for 14.5 ± 2.2 days. The nests were built on thirty plant species, andProtiumicicariba(DC.) Marchand. was the plant species most commonly used for nesting. The breeding parameters of the Tropical Mockingbird are similar to those of other Mimidae species. The knowledge gained from this study makes the Tropical Mockingbird a good choice for future studies, particularly for testing ecological and evolutionary hypotheses regarding life history attributes, habitat selection and parental investment.

The Breeding Biology of the Endemic Azores Woodpigeon Columba palumbus azorica

The Azores Woodpigeon Columba palumbus azorica is considered an endemic subspecies and is currently listed in the Annex I of the EU Birds Directive. However, despite its status, the bird has rarely been studied and is classified as ‘Data Deficient’ in the Portuguese Red Data Book. Herewith, we present the first results on the breeding biology of this subspecies, based on data collected from November 2012 to October 2014 on Terceira Island. Data were obtained by monitoring nests, and additional information on breeding phenology was provided during regular counts from 100 points distributed over the island. Fifty-four nests were found mainly in exotic trees, suggesting that the species does not depend on the highly degraded native laurel forest for nesting. Egg-laying occurred from late-February to late-September, reaching its peak in May; the main laying period lasted 140 days from 1 April to 19 August. Mean clutch size (±SE) was 1.77 ± 0.06 eggs (range 1–2 eggs) and did not vary with time. Overall breeding success, calculated using the Mayfield method, was amongst the lowest ever detected for this species across its breeding range: 0.091 ± 0.048 (SE). Extreme weather events and predation by introduced mammals are likely to explain high nest failure. The population is likely to have undergone a period of growth since 1992, following a period in the 1960's when the bird was very scarce in the Archipelago due to hunting pressure. In recent years, farmers have increasingly complained to the Regional Government about damage to crops, including vineyards, caused by the Azores Woodpigeon on some of the Azorean islands.

Disequilibrium in Trait-Climate Relationships of Trees and Birds

Climate change is expected to drive changes in the structure of ecological assemblages, but these responses might show considerable time lags. If these lags are large, then the observed composition of assemblages will fall out of equilibrium with current climatic conditions. This disequilibrium has several expected signatures, including trends in the magnitude of climate relationships through time and stronger climate relationships across space than through time. Here, I describe spatial and temporal patterns of functional assemblage composition of birds and trees and ask whether there is evidence of disequilibrium between climate and functional assemblage structure. I used bird assemblage data from the Breeding Bird Survey (BBS) and tree data from the Forest Inventory and Analysis program (FIA), in both cases spanning the continental United States and covering the time period 1970-2016. To describe functional assemblage composition, I used the community weighted means of five functional traits for trees and six traits for birds, and fit linear models to explain the variation in composition through time and across space. For most traits, spatial relationships were much stronger than temporal relationships, consistent with lagged responses of assemblages to climate change. Several of the traits showed trends over the study period, in some cases associated with trends in mean annual temperature. Others showed dynamics in the spatial relationships between climate and trait values. For example, the mean clutch size of birds depended only weakly on temperature in the early study period, but the relationship became strongly negative by 2016. While precipitation was often an important predictor of spatial patterns of functional composition, it was typically weakly correlated with the temporal patterns. This likely reflects the fact that temperature experienced more consistent long-term trends over the study period, whereas large year-to-year fluctuations in precipitation prevent composition from ever coming into equilibrium with precipitation in a particular year. Overall, there was substantial evidence of disequilibrium between functional assemblage composition and climate.

Variations in fecundity over catchment scales: Implications for caddisfly populations spanning a thermal gradient

Abstract Population sizes of stream insects depend on the number of eggs that enter the benthos. Densities of oviposited eggs have been linked to densities of oviposition habitat, but variability in fecundity has not been explored. Fecundity may differ between sites where females experience different thermal environments during development, because insects generally grow larger and produce more eggs in cold places (e.g. high elevation and latitude). We predicted that because the fecundity of emerging females should increase with elevation then the numbers of eggs in oviposited egg masses (clutch sizes) should also increase with elevation. Alternatively, individuals may routinely disperse along channels or between rivers, mixing individuals that have grown and developed in different thermal environments, in which case clutch sizes may not vary with elevation but could vary greatly within sites. We tested these hypotheses across an elevation gradient of 250–1,080 m above sea level, in seven streams in southeast Australia. We surveyed the fecundity of three species of caddisflies (Trichoptera: Hydrobiosidae) in 2009 (eight sites) and 2010 (17 sites). Female hydrobiosids attach their entire clutch of eggs to an emergent stream boulder, in a single egg mass. At each site we censused the number of egg masses in two random 50 m stretches and photographed a sample of egg masses. Clutch sizes were quantified by counting eggs from the photographs. From numbers of egg masses and mean clutch size per site, we estimated the number of individual eggs per site, to determine whether spatial differences in clutch size affect patterns of egg supply. Potential trade‐offs between egg number and size were also examined. Strong thermal gradients were observed in both years. Sites at lowest elevations were 4.8°C (2009) and 3.6°C (2010) warmer than sites at highest elevations, and accumulated 392 (2009) and 361 (2010) more degree‐days (>0°C) over a period of 88 days. Clutch sizes of each species varied markedly within and between species but did not differ along the thermal gradient. Within species, 83.7–93.7% of variation in clutch size was expressed within sites. Relatively little variation occurred between sites or rivers. Within species, counts of egg masses adequately described relative egg supply to each site, because clutch sizes were similar between sites and rivers. Comparing egg supply between species, however, required including clutch sizes to estimate supply. Egg size differed within but not between species. Significant but small variations in egg size were trivial compared to much larger variations in clutch size. Our results suggest that any spatial differences in fecundity caused by temperature may be erased by dispersal, such that females from multiple locations mix between sites prior to oviposition. A warming global climate may reduce the fecundity of ectotherms such as aquatic insects but consequences for populations are difficult to predict. Moreover, climate‐related effects on fecundity may not be apparent when dispersal by individuals between elevations mixes any effects of climate change on fecundity.

Breeding Biology of Montagu's Harrier Circus pygargus in South-Eastern Spain

Recent changes in farming throughout Europe are threatening steppe birds, such as Montagu's Harrier Circus pygargus, a steppe raptor that nests in cereal crops, and is therefore threatened by the destruction of its nests by harvesters. Here we analyse the reproductive biology of Montagu's Harrier in Granada province of (south-eastern Spain), based on 184 nests monitored from 2003 to 2014. The mean laying date in our study area is one of the earliest recorded for the species, and mean clutch size one of the lowest, as expected considering the latitude at which the population is located. We also found that laying date was progressively earlier over the study period, whereas both clutch size and productivity have increased. The results show high reproductive success (82%), with a productivity of 2.67 fledglings per nest. However, this high productivity was achieved thanks to the nest rescue campaigns. Had the nests saved been lost, productivity would be only 1.47 fledglings per nest. Therefore, nest-rescue campaigns are fundamental for the conservation of the Montagu's Harrier population of south-eastern Spain.—Moreno-Rueda, G., Lopezosa, P. & Rivas, J.M. (2019). Breeding biology of Montagu's Harrier Circus pygargus in south-eastern Spain. Ardeola, 66.1: 3–11.

Effect of food quality on life history traits of <i>Daphnia galeata</i> and <i>Bosmina fatalis</i>

枝角类体内氮磷比与生活史策略的选择密切相关，大型枝角类通常体内含磷量高、个体生长快、生殖率高，而小型枝角类体内含磷量低，个体生长相对较慢、生殖率低.由于大型枝角类对磷的需求比较高，我们假设大型枝角类生活史各参数对食物磷缺乏比小型枝角类更为敏感.本研究比较分析了食物碳磷比对流溪河水库两种枝角类（盔型溞（Daphnia galeata）和脆弱象鼻溞（Bosmina fatalis））生活史各参数的影响.实验设计了3个食物质量处理组：高磷（碳：磷=105）、中磷（400）和低磷（1450），食物浓度均为2 mg C/L的蛋白核小球藻（Chlorella pyrenoidosa）.脆弱象鼻溞内禀增长率、幼溞生长速率、平均每窝产仔量和首次生殖时体长均随着食物碳磷比的升高而显著下降；首次生殖时间则随着食物碳磷比的升高而显著延长；新生幼溞体长在各食物处理中无显著差异.盔型溞幼溞生长速率、平均每窝产仔量和首次生殖时体长均随着食物碳磷比的升高而显著下降；内禀增长率和新生幼溞体长在高磷处理组显著高于中磷和低磷处理组，但在中磷和低磷处理组无显著差异；首次生殖时间在高磷处理组显著短于中磷和低磷处理组，但在中磷和低磷处理组无显著差异.结果表明，食物的磷缺乏降低了两种枝角类的内禀增长率和幼溞生长速率，并延长了性成熟时间；盔型溞的内禀增长率、首次生殖时间和平均每窝产仔量等生活史参数受食物磷限制的程度小于脆弱象鼻溞，导致盔型溞对脆弱象鼻溞有竞争优势.;Primary life history parameters of cladocerans are linked to body N:P stoichiometry. Large cladocerans tend to have higher phosphorus content, grow more rapidly, and produce more neonates than small cladocerans. The entire difference in specific phosphorus content of these two cladoceran groups can be related to differences in RNA content. Large cladocerans' high growth rate requires a high ribosomal complement for extensive protein synthesis coupled to high growth rate. Therefore, large cladocerans' life history straits are supposed to be more sensitive to food phosphorus deficiency than those of small cladocerans. We examined the effects of food stoichiometry quality (different carbon:phosphorus[C:P] ratios)on life history straits of two common cladocerans species in South China, Daphnia galeata and Bosmina fatalis. D. galeata and B. fatalis were fed saturating concentrations of food (Chlorella pyrenoidosa, 2 mg C/L)of high P (C:P=105), medium P (400), and low P (1450). Population intrinsic growth rates varied from 0.36 to 0.46 d^-1 and 0.18 to 0.39 d^-1, neonate body growth rates varied from 0.31 to 0.52 d^-1 and 0.10 to 0.38 d^-1, age at first reproduction varied from 4.6 to 7.2 d and 3.4 to 7.2 d, mean clutch size varied from 11.5 to 15.1 ind. and 1.6 to 2.3 ind., and newborn neonate body size varied from 0.65 to 0.71 mm and 0.22 to 0.23 mm for D. galeata and B. fatalis, respectively. Neonate body growth rate, population intrinsic growth rate, body size at first reproduction and mean clutch size tend to decrease, while age at first reproduction tend to increase with the increasing of food C:P ratio in both species. Newborn neonate body size was much higher under high P condition than those under medium and low P conditions in D. galeata, but showed no significant difference among treatments in B. fatalis. Our results suggest that population intrinsic growth rate, neonate growth rate and age at first reproduction of D. galeata tend to be less sensitive to food phosphorus deficiency than those of B. fatalis, and D. galeata is competitively superior to B. fatalis.

Breeding biology of the White-throated Kingbird (Tyrannus albogularis) in Brazil and Bolivia

ABSTRACT The White-throated Kingbird (Tyrannus albogularis) is a widespread species in north-central South America, where it inhabits a variety of open to semi-open habitats. The breeding biology of the species is almost unknown. We describe the reproduction of the species based on 34 nests found in southeastern Brazil and eastern Bolivia since 2004, and eggs and nests found in museum collections. The breeding season lasts from mid-September to mid-February throughout its breeding range. The nest is cup shaped and supported from below. Nests were built with woody stems, grass stems, rootlets, and palm fibers. Mean clutch size was 2.3 eggs, which were ovoid with a pink ground coloration, covered by dark spots and blotches of variable size and color concentrated at the rounded end. The mean incubation period was 16.3 d and the nestling period was 18 d.

Improved protocol for rapid zebrafish growth without reducing reproductive performance

Despite widespread use of zebrafish Danio rerio (Hamilton) as a model organism for finfish aquaculture, genetics and molecular biology, husbandry methods and nutrition have not been standardised. We characterise a protocol for rearing zebrafish using a recently developed combination of environmental parameters that yield rapid growth rates: high densities of live food organisms (marine rotifers and brine shrimp nauplii), low salinity, continuous light and algal turbidity during larval and early juvenile stages (5–21 days post fertilisation, dpf) followed by a transition to conventional rearing methods (dark/light photoperiod, freshwater). We assessed a range of larval fish densities in a stagnant water system with continuous ad libitum feeding until 21 dpf and periodic water changes. Fish stocking densities of 12–22 fish/L gave maximum growth rate and growth rate declined as stocking density increased past this threshold. Survival rates during 5–21 and 21–42 dpf were 87 ± 9 and 98 ± 3% respectively. Mean ± SD weight and length were 64 ± 9 mg and 19.4 ± 1.0 mm at 21 dpf and 245 ± 28 mg and 30.4 ± 1.5 mm at 42 dpf. Fertility was assessed at 66 ± 3 dpf. Mean clutch size was 232 ± 124 oocytes/female and fertilisation rate was 72 ± 16%. This protocol will significantly increase productivity in zebrafish facilities.

Life history of the Rio Grande leopard frog (Lithobates berlandieri) in Texas

ABSTRACTWe ascertained various life-history traits from an examination of 310 museum specimens of the Rio Grande leopard frog (Lithobates berlandieri) collected during 1907–2016 from Texas, USA. Lithobates berlandieri was captured during every month of the year except November, and adults were most frequently encountered during January–September, with a distinct peak in May. Mean body size of adult males (69.5 mm) was smaller than that of adult females (77.5 mm), and adult body sizes tended to be smaller at higher latitudes, a trend that was more pronounced in males. Females were gravid during January–September, and most gravid females were captured from late winter to early summer. Gonadal enlargement in males was generally high throughout January–September with no detectable seasonal increase. Feeding became widespread in both sexes during May–June shortly after a spring breeding bout. Spent females (ovarian stage 1) were common in July and lipid deposition increased in June/July, signalling oogenesis for breeding in the fall. From 15 gravid females, we estimated a mean clutch size of 3107 eggs which was correlated with female body size, yet egg diameter was not related to clutch or body size. Age to metamorphosis was likely 2–4 months depending upon whether eggs were laid in the winter/spring or late fall. If metamorphosis occurred in May/June, the minimum size at sexual maturity could have been reached in 7–8 months for adult males (50.1 mm) and in 9–10 months for adult females (57.2 mm). Mean adult body sizes, however, may have taken 14 to 17 months to reach. A synthesis across Texas populations suggests that the breeding season extends almost continuously from the fall through the winter and spring until mid-summer and is interrupted by extreme temperatures in the winter and summer.

Reproductive Ecology of the Brazilian Merganser (Mergus octosetaceus) in Serra da Canastra National Park and Adjacent Areas, Minas Gerais, Brazil

The Brazilian Merganser (Mergus octosetaceus) is globally classified as a Critically Endangered species and is one of the world's rarest waterbirds. The breeding ecology of this species was studied between 2005 and 2016 in the region of the Serra da Canastra National Park, Minas Gerais, Brazil. Between two and six nests were followed each year, with mean of 4.1 (n = 18 nests). Mean clutch size was 6.7 ± 0.9 (n = 31 clutches) with a range of five to eight eggs per nest. Average incubation constancy was 88.3% (n = 3 nests) and ranged from 86.7% to 90.7%. Mean incubation temperature and humidity were obtained from three nests and ranged from 33.6 °C to 33.8 °C and 65.9% to 70.2% respectively. The nest success was 77.1%, and the duckling survival (up to 8 weeks) was 53.8%. Nest predation was relatively low at 7.9%, and the annual reproductive output was 4.7 ducklings/female. Data on breeding ecology is fundamental in guiding conservation strategies, both in the field and in captivity.

Breeding biology of the Pale-bellied Tyrant-manakin Neopelma pallescens (Aves: Pipridae) in south-eastern Brazil

ABSTRACTThe Pale-bellied Tyrant-manakin (Neopelma pallescens) inhabits semi-deciduous and riparian forests in central-north South America. Contrary to most manakins, there is no evident sexual dichromatism in the species and little is known about its breeding biology. We studied the breeding biology of a colour-banded population of the species from August to December 2016 and from August to October 2017 in the Campus Florestal of the Universidade Federal de Viçosa, south-eastern Brazil. The breeding season extended from early September to late November. The species is promiscuous, with males exhibiting simple courtship displays (exploded leks) in individual arenas. The nest (n = 13) is a cup attached by its top lip between forked branches and is very simple, with a structural layer made with dry grass stems and heads, attached to the branch with spider silk. The outer and lining layers are absent. The mean clutch size was 1.8 eggs (n = 11), which are oval and pale coloured, covered with spots of different shades of brown, often concentrated in the larger pole. Mean egg length and width (± SD) were 21.0 ± 0.9 × 15.8 ± 0.7 mm (n = 14) and the mean weight was 2.8 ± 0.4 g (n = 10). The incubation period could not be estimated, but the nestling period was 15 days (n = 2). The simple percentage of successful nests was 15.4%, with 76.9% of the nests depredated and 7.7% abandoned. This is the first detailed study about the breeding biology of any Neopelma species, providing relevant data for the study of the evolution of life history strategies not only for the genus, but for the whole family Pipridae.

A Nearctic-Neotropical Migratory Songbird\u2019s Nesting Phenology and Clutch Size are Predictors of Accumulated Cyclone Energy

The breeding season phenology of Nearctic-Neotropical migratory songbirds is constrained by subsequent seasons resulting in single-brooded behavior (one successful clutch per year) in some species. Early cessation of the nesting season prior to an active hurricane season will allow for behavioral plasticity during a physiologically challenging migration. Hurricane activity shows a high degree of inter-annual variability. I show that a single-brooded Nearctic-breeding species’ (Catharus fuscescens) nesting phenology and clutch size are significant predictors of Accumulated Cyclone Energy. The most skilled predictive model includes both mean clutch initiation date and mean clutch size (R2 = 0.84). Spearman rank correlation coefficients for both predictors with subsequent major hurricanes (1998–2016) are −0.55 and 0.52, respectively. Therefore, May and June clutch initiation and clutch size showed stronger correlations with subsequent hurricanes than early season (prior to August) meteorological predictions widely publicized by CSU, NOAA, and TSR (≤0.45, 2003–2014). Rainfall anomalies in the southern Amazon basin associated with ENSO cycles are a possible proximate cue affecting phenology and clutch size. This discovery potentially has far-reaching ornithological, meteorological, and social implications and shows that tropical storms significantly constrain breeding season behavior providing renewed evidence that hurricane activity is a primary factor regulating Nearctic-Neotropical migratory songbird populations.

Advanced Breeding Time in Line with Climate Did Not Affect Productivity of Great Reed WarblersAcrocephalus arundinaceusDespite the Shortening of the Nestling Period

Recent climate warming has resulted in advancement in laying dates and changes in various bird breeding parameters. The study of the breeding biology of Great Reed Warblers Acrocephalus arundinaceus was carried out at Milicz fishponds (SW Poland) during 18 discontinuous breeding seasons between 1970 and 2017. Over the study period, Great Reed Warblers started breeding progressively earlier; both the earliest and median first egg laying dates advanced, whereas the latest laying dates remained unchanged. Egg volume and clutch size did not change between 1972 and 2017. Mean clutch size of all nesting attempts was 4.8 (SD = 0.69, n = 1135). Nestling growth rates were similar in 1971 and 2016. Nestling period shortened during the study period. The decrease amounted to 0.7 days between 1970–1984 and 2004–2017. No temporal trends in fledgling production were observed. The proportion of successful broods varied considerably between years (range: 37%−76%) but did not show any consistent trend throughout the study period. More cases of Cuckoo Cuculus canorus parasitism were observed in 1997−2017 than in 1970−1984 (7% of nest losses versus 0 respectively), whereas starvation of nestlings was more frequent in 1970−1984 (10% versus 2% of nest losses). Breeding densities varied between seasons with no significant trend across the study years. This study concludes that the advanced start of breeding has not significantly influenced basic parameters of breeding ecology of the Great Reed Warbler.

Reproductive ecology of the endangered Beal's-eyed turtle, Sacalia bealei.

The Beal’s-eyed turtle (Sacalia bealei) is endemic to southeastern China and endangered due to poaching and habitat loss. Knowledge of S. bealei ecology is lacking and this study provides baseline information of its reproduction in a natural environment. We studied the reproductive ecology of S. bealei using X-ray, spool-and-line tracking, and direct observation. Six nesting females were successfully tracked and their nesting behaviors are documented in detail. Females produced a mean clutch size of 2.2 eggs (range 1–3). The hard-shelled eggs were ellipsoidal with a mean length of 45.50 mm, a mean width of 23.20 mm, and mean weight of 14.8 g. The relative clutch mass was 9.47%, while the relative egg mass was 4.60%. The mean incubation period was 94.7 days with a mean nest temperature of 25.08 °C. Hatchlings had a mean weight of 9.7 g, carapace length of 40.1 mm, carapace width of 33.3 mm, carapace height of 17.4 mm, plastron length of 31.6 mm, and plastron width of 25.4 mm. The results of this study provide important information to inform conservation plans and ex-situ breeding for this endangered species.