Complete Clutch Research Articles

Clutch fullness index as an early indicator of overexploitation of the Southern King Crab: Implications for fisheries management

Southern king crab is a high-value fishing resource commercially exploited in the Argentine Patagonia (south 44° S) since 2004. The ovigerous mass size of females, estimated as the clutch fullness index (CFI), has been used as a proxy for qualitative fecundity and an indicator of population health. In 2015, the use of CFI allowed the early detection of signs of overexploitation of the Southern king crab. This study aimed to assess temporal variations in the CFI in relation to fishing effort and management measures. Data were collected from commercial vessels between January and May from 2012 to 2020 in the Central Patagonian Sector (comprising the San Jorge gulf and adjacent shelf waters, 43°30′- 48°S). The Correspondence Analysis and hierarchical cluster analysis showed that the CFI varied among years. The variation of the CFI was opposite to the fishing effort. The CFI decreased between 2015 and 2017 (from 80% of females with 100% CFI in 2014 to 43% in 2017), and increased since 2018 (from 57% in 2018 to 78% in 2020). This is probably due to the implementation of two new management measures (extended closed season and the regulation of an annual catch quota). Two indicators of L. santolla reproductive status are proposed based on empirical data. The first one is the proportion of non-ovigerous mature females during the incubation period, which could reflect a male shortage during the mating period must not exceed 10% and the second one is the proportion of females with a complete clutch must be greater than 40%. The CFI variations and the proposed indicators can constitute an alternative to the crabs traditional management.

Первый опыт использования фотоловушки при изучении гнездовой биологии и экологии змееяда в Национальном парке Алтын Эмель в 2023 году

A Short-Toed Eagle (STE, Circaetus gallicus) nest was observed over the reproductive period of 2023 in Altyn-Emel National Park located in the south-east of Kazakhstan (Zhetysus oblast of the Republic of Kazakhstan). The nest location was on the right bank of the Ile River in arid terrain of clay conglomerate, 12–15 km east of the dry lowland massif of Ulken Kalkan (Ile Forestry section “Zhagalybai”) near the “Kosbastau” area. The nest was built on a live Turanga poplar (Populus diversifolia) about 5 m high on one of two dried branching trunks in the apex of the tree at a height of 3.7 m. Judging by the massiveness of the nest, this was not the first year that this pair of Short-Toed Eagles nested here. A nest of Saxaul Sparrow (Passer ammodendri) was located 50 m away on another turanga tree in a hollow formed by the fall of a dry branch (fully-feathered nestlings observed May 8). At least one pair of Indian Sparrows (Passer indicus) was nesting in the mass of the STE nest. One egg was observed in the STE nest on May 8, which represents a complete clutch, characteristic of the species. On the same day a camera trap (Digital Trail Camera HH-662, 16mp) with a combined trigger mode (3 images and 20-second video with a 20 min delay interval) was installed on a dry turanga poplar 1.7–2.0 m from the nest. Over the next three months, from 8 May to 10 August of this year, the incubating pair, and subsequently the hatched nestlings, were observed, until the nestlings fledged, though regularly returned to the nest from 10–15 August. To note, these were fragmentary, rather than constant observations by the camera trap due to the fact that the installed flash drive was periodically completely filled up and the charge of AA alkaline batteries ran out multiple times. Both individuals of the pair tolerated the close proximity of the camera trap almost immediately, and the camera trap recorded the pair taking turns at egg incubation as early as May 10. They sometimes changed turns in the early morning hours, almost immediately after sunrise. During egg incubation, one of the adults brought a freshly broken 70 cm twig of Elaeagnus (Elaeagnus oxycarpa) with leaves and ripening fruit to the nest when taking over incubation from its partner. On June 26, a nestlings covered in white down was observed in the nest. It also had pin feather stubs and opening pin feathers (pin feathers that are open by one-quarter to one-third) of flight feathers and contour feathers and back plumage that had already begun to open. It also had pins among the downy plumage on the head. When checked on July 19, the nest box contained an almost fully feathered nestlings, with growing remex and rectrix feathers. At times it actively flapped its fully opened wings while bouncing in the nest, evidently preparing to fledge. Both adults fed the nestlings on various species of snakes, including the Arrow Snake (Psammophis lineolatus) observed on July 3 and 14, Sand Boa (Eryx tataricus) observed on July 12, and Rat Snake (Elaphe dione) observed on July 7 and 15. Notably, the nestlings used its beak to pull the snakes out of the throat and esophagus of the parents, who had at that point swallowed the snake by half or even completely (July 3, 6, 7, 12, 15), at the same time the nestlings, helping itself, sometimes grasped the pulled snake with one of its paws (July 7). The recorded frequency and abundance of snake prey items may indirectly indicate a relatively high occurrence and abundance of snakes on the territory of the national park in its coastal part and quite a rich prey base of these reptiles in contrast to the neighboring geographical area in the Southern Pribalkhashie, where Hedgehogs (Erinaceus auritus) prevailed as prey items at the stage of feeding the fledged chick. Among the prey items of STEs recorded by camera trap (photos and video) in Altyn-Emel in 2023, hedgehogs were not recorded. Notably, on July 9, the nestlings began to pull sharply the end of tail from the beak of the adult, practically in the same way as in cases with snakes brought by parents, and the adult then regurgitated a nearly completely swallowed adult male steppe agama (Trapelus sanguinolentus). The authors are grateful to Alisher Kanapiy and Kanat Ospankul for their assistance with the field research, installation and periodic checking of the camera trap.

OBSERVATIONS REGARDING THE BIOLOGY AND THE ECOLOGY OF THE SPECIES TURDUS PILARIS LINNAEUS 1758 IN THE WESTERN HALF OF ROMANIA

The paper presents the results of the researches performed by the authors between 2000-2019 regarding the biology and the ecology of the species Turdus pilaris L. in the western half of Romania.The extension of the territory, breeding, clutch size, behaviour, number of generations , the phenology and food were studied. The height of nests above the ground varied till to 20 meters in a different trees. The nest is cup – shaped and the material of construction is extremely different : moss, roots, dry twigs, ground mixed with grass, herbs. It presents 2 -3 yearly generations, a complete clutch consists of 5 – 6 eggs. The post – embrionic development lasts 12 – 16 days. The phenology is different : in high hilly and the mountainous areas the species is sedentary, in low hilly and plain areas the species is partial – migratory or passage or in many times winter visitor. The food is extremely different: insects, fruits, worms, spiders, molusca, little mammals.

Asymptotic Analysis of Double-Row Riveting of Kirchhoff Plates

Two Kirchhoff plates are considered that are joined by means of two rows of rivets posed with the small period h and modeled by Sobolev point transmission conditions. A new and unexpected effect is observed, namely the almost complete clutch of the plates occurs even for an exponentially small (with respect to h) distance between the rows in the mirror symmetry case. The same effect appears in the case of rivets in chessboard order only for the power-law smallness of the distance. These results are obtained with the help of analysis of boundary layer phenomena. Conditions are found to provide the hinge joint of the plates with friction at the limit.

Models of riveting: asymptotic analysis of the Kirchhoff plates with Sobolev point conditions

The Sobolev embedding theorem implies the correct setting at isolated points of the Dirichlet condition or the transmission conditions which simulate contact welding, binding by bolts or screws and so on. We consider the problems on bending the Kirchhoff plate with periodically distributed point supports and the joint of two plates by rows of rivets. Asymptotic analyzes performed provide asymptotic expansions of solutions and error estimates, namely, the one-dimensional model of a narrow plate and the transmission conditions at the common edge of two plates. The results of homogenization differ seriously in the cases of one or several rows of supports and rivets. In particular, one-row riveting provides only hinge joint of the plates (jumps of the rotation angles are allowed) but two-row riveting provides almost complete clutch which all elastic fields become in main continuous at the common edge.

Models of Riveting: Asymptotic Analyses of Kirchhoff Plates with Sobolev Point Conditions

The Sobolev embedding theorem implies correct formulation of the Dirichlet condition at isolated points or transmission conditions that simulate contact welding, bolt or screw fastening, etc. The problems on bending the Kirchhoff plate with periodically distributed point supports and the joint of two plates by rows of rivets are considered. The asymptotic analysis performed provides asymptotic expansions of solutions and error estimates, namely, the one-dimensional model of a narrow plate and the transmission conditions at the common boundary of two plates. The results of homogenization differ seriously in the cases of one or several rows of supports and rivets. In particular, one-row riveting provides only a hinge joint of plates (discontinuities in the rotation angle are allowed), but two-row riveting provides an almost complete clutch at which all elastic fields become, in main, continuous at the common edge.

Eviction Notice: Observation of a Sterna hirundo (Common Tern) Usurping an Active Sternula antillarum (Least Tern) Nest

Although nest usurpation is common in some species and orders of birds, usurpation has rarely been reported for Sterninae. We observed a Sterna hirundo (Common Tern) egg in an active Sternula antillarum (Least Tern) nest with a complete clutch in a mixed-species Sterninae colony in Chesapeake Bay, MD, in May 2018. Based on observations from a game camera following usurpation, Common Terns incubated the mixed-species clutch, with no further parental care provided by the usurped Least Tern. The clutch never hatched, as the Common Terns abandoned the nest prior to the hatching. While we suspect that Common Terns usurped the Least Tern nest, alternative scenarios may explain how the Common Tern egg was documented in a Least Tern nest.

Two new ootaxa from the late Jurassic: The oldest record of crocodylomorph eggs, from the Lourinhã Formation, Portugal

The Late Jurassic Lourinhã Formation is known for its abundant remains of dinosaurs, crocodylomorphs and other vertebrates. Among this record are nine localities that have produced either dinosaur embryos, eggs or eggshell fragments. Herein, we describe and identify the first crocodiloid morphotype eggs and eggshells from the Lourinhã Formation, from five occurrences. One clutch from Cambelas, composed of 13 eggs, eggshell fragments from Casal da Rola and Peralta, one crushed egg and eggshells from Paimogo North, and four crushed eggs as well as eggshell fragments from Paimogo South. We observed and confirmed diagnostic morphological characters for crocodiloid eggshells and which are consistent with a crocodylomorph affinity, such as the ellipsoidal shape, wedge-shaped shell units, triangular extinction under cross-polarized light, and tabular ultrastructure. This material is distinctive enough to propose two new ootaxa within the oofamily Krokolithidae, Suchoolithus portucalensis, oogen. and oosp. nov., for the material from Cambelas, the most complete clutch known for crocodiloid eggs, and Krokolithes dinophilus, oosp. nov., for the remaining material. These are the oldest crocodylomorph eggs known, extending the fossil record for this group to the Late Jurassic. Furthermore, except for the clutch from Cambelas, the material was found with theropod eggs and nests, in the other four occurrences, which seem to suggest some form of biological relationship, still unclear at this point.

Partial Incubation During the Egg-Laying Period in the BlackcapSylvia atricapilla

Partial incubation refers to short bouts of incubation during the egg laying period. I determined the occurrence of partial incubation and its association with the number of eggs in the nest at its onset, in the Blackcap Sylvia atricapilla. Additionally, I studied the relationships between the occurrence of partial incubation at a given number of eggs, air temperature and time of day. At each stage of egg-laying, two nest checks were done each day to establish if the clutch was incubated, until 5 eggs were laid; in this study, a clutch of five was a complete clutch. Incubation of one-, two-, three- and four-egg clutches was observed in 0.0%, 34.2%, 72.2% and 95.8%of the nest checks, respectively. Of the two daily checks, incubation was observed only once in 51.8%, 37.0% and 8.3% of two-, three- and four-egg clutches, respectively, for nests with confirmed incubation. There was no relationship between either air temperature or the time of the nest check and whether or not a clutch was incubated. A significant increase in temperature of the eggs occurred only after the fourth egg was laid.

Three-dimensional finite element model of an automotive clutch for analysis of axial vibrations

Recent progress made in making clutches lightweight and in reducing torsional vibrations has led to the emergence of new vibroacoustic phenomena due to the out-of-plane vibrations of the clutch. These vibrations are generated along the axial direction of the clutch system. Contrary to torsional vibrations that can be simulated by unidirectional lumped-mass models, axial vibrations require a three-dimensional approach to describe the dynamics of the components. Finite element models are widely used to design or optimize the components of the clutch. However, no finite element model of a complete clutch has been developed for analysis of axial vibrations. The main difficulties are the complexity of the system, the great number of non-linearities, the difficulties of instrumentation for validation and the variation in the behaviour along the engagement stroke. This paper provides a validated three-dimensional finite element model of the dynamic behaviour of the clutch for studying axial vibrations. The model simulates the axial static and dynamic characteristics of the clutch. Model accuracy and validation are achieved by comparing the numerical results with the experimental data. The results show the crucial parameters to consider in order to reproduce correctly the non-linear axial behaviour and the dynamic characteristics of the clutch system, namely the orthotropic behaviour of the friction material and the geometrical parameters of some components that should be detailed. Validation is carried out on each component and for the system assembly by dedicated experiments and instrumentation.

Density-dependent effects on nesting success of temperate-breeding Canada geese

Density-dependent effects on reproduction can arise through variation in habitat quality or increased competition and interference among neighbours. Negative effects have been found in avian populations and these have been mainly attributed to food limitations. In this study, we investigated whether density-dependent effects could result from either heterogeneity in habitat suitability, interference among neighbours, or predation. To test these hypotheses, we collected data over eight years in a growing population of temperate-nesting Canada geese Branta canadensis maxima. We compared different parameters of nesting success of geese between two sites characterized by different nest densities and looked at the effects of nest proximity on these parameters within each site. At the landscape level, we found density-dependent effects due to variation in habitat quality associated with predation probabilities and flooding events. At a finer scale, nesting success declined with proximity to neighbours, probably due to increased aggressive interactions among pairs. However, complete clutch predation showed both positive and negative density-dependence, due to differences in predator community at each site. We concluded that density-dependent effects reduced nesting success of Canada geese through both heterogeneity in habitat safety and agonistic interference between neighbours but that density-dependent effects could also be positive in some instances.

First record of a complete giant theropod egg clutch from Upper Cretaceous deposits, South Korea

Here, we report the first occurrence of a complete Macroelongatoolithus clutch from outside of China. Excavated from Upper Cretaceous strata of Aphae-do in Shinan-gun, Jeollanam-do Province, South Korea, the clutch of 19 eggs is characterised by large, elongate, symmetrical eggs arranged in a single-layered ring-shaped clutch. Eggs are inclined towards the centre of the 2.3-m diameter clutch, and average 41.17 cm long and 15.58 cm wide. Of the 19 eggs, 8 clearly retain a paired configuration. This specimen represents only the second report of large theropod eggs from South Korea and is the most complete Macroelongatoolithus clutch known from the region to date. Eggshell microstructural features are consistent with Macroelongatoolithus xixiaensis (oofamily Elongatoolithidae), previously known only from Cenomanian strata of southeastern China. This first record of a giant theropod egg clutch, here assigned to M. xixiaensis, extends the stratigraphic and paleogeographic range of Macroelongatoolithus eggs and parent animals to include the Campanian of South Korea.

Sliding Mode Position Control of an Electro-Pneumatic Clutch System

This paper presents a nonlinear control synthesis to design a position controller for an electro-pneumatic Clutch By Wire (CBW) system. In order to achieve high reference tracking performance and meet stability specifications, the Sliding Mode Control (SMC) synthesis is applied for controller design. The dynamic model of the CBW system is shown and transformed into an appropriate coordinate system. In this way, the controller can be designed to provide the track of the reference signal with predefined dynamics and reduce the effects of the disturbances on the performance. Moreover a controller reduction possibility is proposed to decrease the code length, memory claim and computing costs for embedded applications. In the paper, the model representation, coordinate transformation, control design strategy and finally the experimental results on a complete clutch bench are demonstrated and evaluated.

Breeding Biology of Olrog's Gull in Bahía Blanca Estuary, Argentina

Aspects of the breeding biology of the world largest Olrog's Gull (Larus atlanticus) colony, in the estuary of Bahía Blanca, Argentina, were assessed for 101, 66, and 47 nests in 2005, 2006, and 2007, respectively. Mean (± SD) clutch size in 2005 was 1.86 ± 0.73 eggs per nest and modal clutch size was two eggs (range = 1–3). The incubation period was 1.67 days longer for A-eggs than for B-eggs (27.44 ± 1.22 days vs. 25.77 ± 1.36 days, respectively; P < 0.001). Incubation length for C-eggs was 25.75 ± 0.96 days. The largest eggs were 31.5% (length), 21.3% (breadth), and 66.5% (volume) larger than the smallest eggs. Mean egg volume in 2006 and 2007 decreased with hatching order, but the magnitude of this change was more pronounced in 2007 than in 2006. Variation in all egg measurements was larger among than within clutches. Hatching success within three-egg clutches was 76.9% in 2005, 81.7% in 2006, and 91.3% in 2007 (P = 0.20). Total egg loss in 2005 reached 16.7% and complete clutch loss was 43.8% during the incubation period. Parameters quantified in this study provide a comparative benchmark for future research on factors affecting breeding parameters in Olrog's Gull from this and other colonies, and lay the foundation for developing effective conservation strategies for the species.

Nest desertion by a cowbird host: an antiparasite behavior or a response to egg loss?

Natural selection can favor songbirds that desert nests containing eggs of the parasitic brown-headed cowbird (Molothrus ater). However, the high variability in desertion of parasitized nests within species is perplexing in light of the typically high costs of parasitism. Because nest desertion can also be a response to partial clutch predation, we first asked if Bell’s vireos (Vireo bellii) deserted nests in response to the presence of cowbird eggs (antiparasite response hypothesis) or to egg removal by predators and female cowbirds (egg predation hypothesis). Second, we asked whether variation in nest desertion was due to intrinsic differences among individuals or to variation in nest contents. We monitored a large number of nests (n ¼ 494) and performed a clutch manipulation experiment to test these hypotheses. The number of vireo eggs that remained in a nest was a strong predictor of desertion both within and among pairs. Neither the presence of a single cowbird egg, which leads to nest failure for this host, nor the number of cowbird eggs received in a vireo nest influenced nest desertion. Furthermore, vireos did not desert experimental nests when we immediately exchanged cowbird eggs for vireo eggs but deserted if we removed vireo eggs and replaced them with cowbird eggs the following morning. Desertion of parasitized nests by Bell’s vireos can be almost entirely explained as a response to partial or complete clutch loss and does not appear to have been altered by selection from brood parasitism. Key words: Bell’s vireo, brown-headed cowbird, egg predation, evolutionary lag, host‐parasite coevolution, Molothrus ater, Vireo bellii. [Behav Ecol]

A fuzzy-QFD approach to supplier selection

This article suggests a new method that transfers the house of quality (HOQ) approach typical of quality function deployment (QFD) problems to the supplier selection process. To test its efficacy, the method is applied to a supplier selection process for a medium-to-large industry that manufactures complete clutch couplings. The study starts by identifying the features that the purchased product should have (internal variables “ WHAT”) in order to satisfy the company's needs, then it seeks to establish the relevant supplier assessment criteria (external variables “ HOW”) in order to come up with a final ranking based on the fuzzy suitability index (FSI). The whole procedure was implemented using fuzzy numbers; the application of a fuzzy algorithm allowed the company to define by means of linguistic variables the relative importance of the “ WHAT”, the “ HOW” –“ WHAT” correlation scores, the resulting weights of the “ HOW” and the impact of each potential supplier. Special attention is paid to the various subjective assessments in the HOQ process, and symmetrical triangular fuzzy numbers are suggested to capture the vagueness in people's verbal assessments.

Within-year nest reuse in open-nesting, solitary breeding passerines

During fieldwork at Lake Sic (46°57’N, 23°54’E), Romania, in the summer of 2003, we observed a strange incident of nest reuse in the Great Reed Warbler Acrocephalus arundinaceus . After first laying a complete clutch of five eggs and then ejecting an experimentally added parasite egg together with two of its own eggs, a new clutch was initiated in the same nest. In Tana (70°16’N, 28°19’E), Norway, in June 2003, we observed a similar incident in the Brambling Fringilla montifringilla . In a nest that was completely depredated when 3-4 eggs had been laid, a new clutch was initiated 8-9 days later. This is as far as we know the first time nest reuse has been documented in Great Reed Warblers and Bramblings.

Have your cake and eat it too: male sand gobies show more parental care in the presence of female partners

Traditionally, male parental effort and mate attraction effort are expected to be in conflict as they compete for the same resource budget. However, the quality of care provided by the male may be of a direct benefit to females and may provide an important mate choice cue. In a laboratory experiment, we examined how males modified their parental behavior with respect to mating opportunity by allowing male sand gobies to mate with a single female either in a big or small nest (a constraint on future mating potential). We then exposed half of these males to the visual stimulus from additional females and recorded male egg fanning and nest building (two components of care), courtship behavior, and reproductive success through out the brood cycle. We found that males fanned longer and more frequently and did more nest construction in the presence of females and in big nests. Males guarding large nests courted females more than did males guarding small nests. All males consumed eggs during the brood cycle, but complete clutch cannibalism was most frequent when males were guarding small nests in the absence of females. The pattern of filial cannibalism that we observed suggests that males prematurely terminated care when their reproductive potential was low, that is, when there was little nest space for additional mating and no mates present. We found no support for a trade-off between mate attraction and parental care. Indeed, taken together our results suggest that males may use parental care as a courtship strategy and that males who invest in mate attraction also have higher parental effort.

The Influence of Partial Clutch Depredation on Duckling Production

Nest depredation is the foremost cause of reproductive failure in waterfowl. Management strategies typically have focused on reducing predator contact with nests, yet the fate of nests after predators have found them has received little attention. Although nest depredation can result in complete clutch loss, nests often are only partially depredated and the remaining clutch may be successful. We investigated the prevalence of partial clutch depredation in dabbling ducks and assessed its influence on duckling production in the Suisun Marsh of California, USA, from 1998 to 2000. Partial clutch depredation by predators was common in all duck species and in all years. Overall, 37% of mallard (Anas platyrhynchos; n = 803), 37% of gadwall (A. strepera; n = 340), 22% of northern pintail (A. acuta; n = 46), 31% of cinnamon teal (A. cyanoptera; n = 16), and 1 of 2 northern shoveler nests (A. clypeata) were partially depredated. Of those nests experiencing a depredation event, 53% of mallard and 50% of gadwall nests were only partially depredated rather than completely destroyed. As a result of partial clutch depreciation, total duckling production was reduced by 10% for mallards and 9% for gadwalls. The female's decision to stay with or abandon the reduced clutch had an important influence on nest success. Mallard and gadwall females abandoned the nesting attempt after partial clutch depredation 37% and 32% of the time, respectively. However, 27% of partially depredated mallard nests and 23% of partially depredated gadwall nests were successful Egg success was 0.60 ± 0.24 (mean ± SD) for mallards and 0.53 ± 0.23 for gadwall. From 1998 to 2000, 22% of mallard and 21% of gadwall ducklings produced in our study area came from partially depredated nests. Although many cluck nests experienced partial clutch loss, they nevertheless contributed substantially to overall duckling production. Incorporating an estimate of egg success, in addition to nest success, may provide a more accurate assessment of waterfowl management strategies.

Reproductive biology of the crab Munida subrugosa (Decapoda: Anomura: Galatheidae) in the Beagle Channel, Argentina

Munida subrugosa was sampled monthly from November 1997 to November 1999 in the Beagle Channel by means of an epibenthic trawl. The reproductive cycle started in May, reflected by the occurrence of ovigerous females. Maximum size of oocytes, maximum value of gonadosomatic index in females (16·8 g mm carapace length [CL]−1) and males (1·6 g mm CL−1), and the proportion (∼70%) of ovigerous females with full egg-clutches occurred in June. Since the proportion of ovigerous females in October was ∼5% and the planktonic larvae reportedly hatch in September, the embryonic development lasted ∼90–120 days. Females and males attained physiological maturity at 9·9 and 8·0 mm CL respectively, and males reached morphometric maturity at 24·4 mm CL. Fecundity was correlated with female size (r=0·85) and was between 124 and 10,750 eggs per female. Average diameter of recently extruded eggs was 0·69 mm (SD±0·06 mm). At the beginning of the reproductive cycle, ovigerous females had partial broods of ∼300 eggs, which represented &lt;5% of complete clutch.