Removal Of Eggs Research Articles

The Frequency of Conspecific Brood Parasitism and the Pattern of Laying Determinancy in Yellow-Headed Blackbirds

In altricial birds, conspecific brood parasitism (CBP) is disproportionately common in species that nest in colonies. We investigated the frequency of CBP in a colonial icterid, the Yellow-headed Blackbird (Xanthocephalus xanthocephalus). Using two criteria for detecting parasitism, we found no cases of CBP in a sample of 69 nests monitored for 522 nest-days. To make sense of this finding, we consider why specific forms of CBP may be lacking in this species. Egg removal experiments demonstrated that Yellow-headed Blackbirds are determinate layers, so a nesting female that also laid eggs parasitically would either suffer a reduced clutch size in her own nest or suffer a delay in initiating her own clutch. Neither territories, nor nest-sites, are limiting for female Yellow-headed Blackbirds, so parasitism by floater females is not expected. Although the destruction of clutches during laying was common during the study, we failed to see parasitism associated with this nest loss. Current information suggests that nest loss may not play an important role in promoting conspecific parasitism in most species.

A design equation for human intestinal nematode egg removal in waste stabilization ponds

Abstract The percentage removal ( R ) of human parasitic nematode eggs in waste stabilization ponds can be described by the empirical equation R = 100 [1 − 0.141 exp (−0.38θ)] where θ is the mean hydraulic retention time (d). The lower 95% confidence limit of this equation. R = 100 [1 − 0.41 exp (−0.49θ+0.0085θ 2 )] is recommended for the design of ponds to meet the WHO microbiological guideline of ≤ one egg per litre for restricted irrigation.

Artificial incubation of crayfish eggs ( Pacifastacus leniusculus Dana) from early stages of embryonic development

Three experiments on artificial incubation of crayfish eggs ( Pacifastacus leniusculus Dana) were carried out under different thermal regimes using a specially designed incubator tested in previous trials. Each treatment included a period of low temperature of different duration. Three flow rates were used in each experiment: 3.0, 1.5 and 0.5 l/min. In all cases the eggs were detached from females at three phases of embryonic development: beginning of gastrulation (mean degree days 230, 18 days after spawning); embryo between closing of the blastopore and appearance of mandibular rudiments (mean degree days 365); and embryo with naupliar appendages (mean degree days 480). The results showed that it is possible to auain acceptable juvenile stage 2 survival rates (58.9%) even though eggs were detached at the earliest embryonic phase (beginning of gastrulation). In the experimental incubator, flow rates could be reduced to 0.5 l/min without decreasing survival. The highest survival to juvenile stage 2 (72.1%) was obtained by delaying egg removal until the appearance of naupliar appendages, and using a thermal treatment of 15.5 ° ± 1 °C preceded by a 3-week period of low temperature (5 ° ± 1 °C) commencing at stripping time.

Communications: Mortality of Coho Salmon Embryos Immersed in a Hypertonic Salt Solution for Varying Exposure Times

Abstract Eggs of coho salmon (Oncorhynchus kisutch) were incubated to the eyed stage and then mechanically shocked to allow for easy removal of dead or infertile eggs. Eighteen lots of approximately 7,190 live eggs were then placed in separate vertical incubator trays and immersed in a hypertonic solution of NaCl for 0–30 min. Mortality was low (1.4–2.4%) for eggs immersed for up to 10 min. For eggs immersed for 20 and 30 min, mortality increased to 9.5 and 81.4%, respectively. In normal hatchery operations where hypertonic solutions of NaCl are used to remove dead eggs by flotation, immersion times of less than 10 min appear to be safe.

Removal of Yellow Warbler Eggs in Association with Cowbird Parasitism

In this study, I quantified the removal of eggs by the Brown-headed Cowbird (Molothrus ater) from parasitized Yellow Warbler (Dendroica petechia) nests. Laying cowbirds removed one warbler egg from about one in three parasitized nests. Assuming the same individual was involved in both acts, cowbirds removed host eggs on a day before or the same day they laid their own eggs (33.3%, n = 8 nests), on the same day (20.8%, n = 5) but after they laid, or on the same or subsequent days (46%, n = 11). As almost half (41%) of the parasitized nests received cowbird eggs before host eggs appeared, many cowbirds that removed eggs had to return to the nest to do so, although burial precluded that at some nests. Return trips increased the chances that a cowbird might mistakenly remove its own egg, especially if it was the only egg in the nest, and that interactions might occur between host and parasite. Explanations for the removal of eggs at the time of parasitism are summarized and two hypotheses are tested. The likelihood of warblers accepting a cowbird egg experimentally introduced into their nests was not influenced by the removal of a host egg at the time of parasitism, as predicted by the "host deception" hypothesis. Yellow Warblers tolerated five- and four-egg clutches being reduced to three eggs (36/37 nests), but abandoned nearly one-third of clutches reduced to two eggs (13/42) and most clutches reduced to one egg (20/22). Only one control nest was deserted (n = 41 and 59 clutches of five and four eggs, respectively). Only four of 13 (31%) clutches reduced to one egg of each of the warbler and cowbird were abandoned, but 11 of 14 (79%) clutches reduced to only one cowbird egg were deserted. None of the 10 clutches reduced to two cowbird eggs was deserted. These results suggest that cowbirds can remove at least two eggs without risking desertion by the warblers. It is not clear why only one egg is removed, when removal occurs in the first place. Cowbirds that manage to ingest eggs they remove undoubtedly gain nourishment.

Detecting Fertility of Hatching Eggs Using Machine Vision I. Histogram Characterization Method

The ability to automatically detect fertile eggs during early incubation would allow timely removal of dead embryos and infertile eggs from incubation thereby contributing to overall hatchery profits. A method using machine vision for detecting well developing eggs during the third and fourth day of incubation was developed. Images of eggs were acquired using backlighting with a high intensity candling lamp. The images were enhanced using a histogram stretch and parameters were computed to describe the shape of the histogram of the resulting image. An algorithm was developed to distinguish fertile from infertile eggs based on histogram shape parameters. The algorithm performed with accuracies of 96 to 100% at day four of incubation and 88 to 90% at day three of incubation.

Reactions of Four Passerine Species To Threats of Predation and Cowbird Parasitism: Enemy Recognition or Generalized Responses?

Abstract Four host species of the parasitic brown-headed cowbird (Molothrus ater) were exposed to taxidermic mounts of a female cowbird, fox sparrow (Passerella iliaca), and common grackle (Quiscalus quiscula) at their nests during their egg-laying or nestling stage. Red-winged blackbirds (Agelaius phoeniceus), a species that accepts cowbird eggs laid in their nests, responded more aggressively to cowbird models early in their nesting cycle, indicating that they recognized the unique threat the cowbird posed. Gray catbirds (Dumetella carolinensis), northern orioles (Icterus galbula), and cedar waxwings (Bombycilla cedrorum) can remove cowbird eggs from their nests and for the most part they responded similarly to cowbird models and the "nonthreatening control," i.e. a fox sparrow. Cedar waxwings were nonaggressive to all the models and may rely on concealment to protect their nests from enemies. Removal of cowbird eggs by puncture ejection is more risky than grasp ejection. Despite this, orioles and waxwings (puncture ejectors) were not significantly more aggressive to cowbird models at egg laying than catbirds (grasp ejectors). Responses of the three rejector species toward the cowbird model did not change over the nesting cycle, indicating further that they do not recognize cowbirds as a unique threat. Rejector species may not recognize cowbirds because they have little experience with them. With the exception of waxwings, all of the hosts recognized the grackle as an enemy and increased their levels of defence from the laying to nestling stages. Three of the host-species did not simply respond in a generalized manner to any intruder at their nests but indeed recognized specific enemies. Considerable interspecific variability exists amongst the four species in defensive behaviours, which may reflect their different nesting habitats.

Detecting Fertility of Hatching Eggs Using Machine Vision II: Neural Network Classifiers

The ability to automatically detect dead embryos or infertile eggs during early incubation would allow timely removal of such eggs from incubation thereby contributing to overall hatchery profits. Neural networks were trained to recognize shape differences in gray level histograms of images of fertile and infertile eggs at early incubation stages. Images of eggs at three incubation stages (days 4, 3, 2) were obtained using a machine vision system with backlighting. The gray level histograms of the images were enhanced and used as inputs to the neural networks. The learning and classification behavior of different configurations of networks were studied. Selected networks were tested on pattern sets not used in training. The best classification accuracies obtained on the testing sets were 93.9% at day 4, 93.5% at day 3 and 67.6% at the day 2 stage of incubation.

Capitula on Stick Insect Eggs and Elaiosomes on Seeds: Convergent Adaptations for Burial by Ants

1. The eggs of many stick insect species (Order Phasmatodea) bear a striking resemblance to seeds. These eggs are not only similar in size, shape, colour and texture to seeds, but in many species bear a knob-like structure known as a capitulum. This structure resembles an elaiosome, a lipid-rich appendage on some seeds known to be an adaptation for burial by ants. 2. We present observations and experiments demonstrating that capitula and elaiosomes are convergent in function as well as in appearance. 3. Capitula, like elaiosomes, promote removal of eggs to ant nests and buried eggs suffer reduced rates of parasitism by wasps

Microbiological Performance of Multi-Stage Stabilization Ponds for Effluent Use in Agriculture

The paper presents data on total and faecal coliform removal and on intestinal nematode egg removal achieved in the Al-Samra stabilization ponds in Jordan during the winter period December 1986 to March 1987. A total retention of 34 days in the series of 10 ponds was able to achieve complete removal of nematode eggs at the pond temperature 12-15°C but was not able to meet the WHO guideline value for faecal conforms of ≤ 1000/100 ml. In addition to retention time having a positive effect on faecal conform die-off, it was shown that surface organic loading, pond pH, BOD5 concentration, and depth, influenced the rate of faecal coliform die-off. It became apparent that interactions existed among the operational and environmental parameters but that the simple time-and-temperature-dependent model for faecal conform die-off was no longer appropriate.

Adaptive tolerance of cowbird parasitism by prothonotary warblers: A consequence of nest-site limitation?

In a study of prothonotary warbler, Protonotaria citrea, breeding ecology in which nest-site densities were manipulated, 21% of 172 warbler nests were parasitized by cowbirds, Molothrus ater; a relatively high frequency of parasitism compared to the majority of hole-nesting species. Cowbirds reduced warbler nest success by approximately 25%, primarily through egg removal by female cowbirds and lowered hatching success of warbler eggs. However, the impact of cowbird parasitism on warbler nesting success was relatively low compared to that reported for the majority of host species. Although female warblers accepted parasitism in 81% of cases, parasitized nests were abandoned significantly more frequently than were unparasitized nests, with the probability of nest desertion being contingent upon the numbers of nest-sites available on the territory. Similarly, the overall tendency for females to renest following either a successful or, especially, a failed nest was related to nest-site availablity. Timing of parasitism in relation to stage of the nest or time of the season did not significantly influence nest desertion by warblers. Thus, prothonotary warbler females may usually be forced to accept cowbird parasitism as a consequence of nest-site limitation. Relatively low costs associated with accepting cowbird eggs may be chosen by warblers only as an alternative to not breeding. These reuults support the hypothesis that acceptance of parasitism may be adaptive when the costs of rejection outweigh the costs of acceptance of parasite eggs.

Experiments on Indeterminate Laying in House Wrens and European Starlings

Although long studied, determinate and indeterminate laying patterns in birds have not been related to avian ecology. House Wrens (Troglodytes aedon) often experience egg removal by potential nest usurpers, while European Starlings (Sturnus vulgaris) commonly experience both egg removal and egg addition by conspecific brood parasites. We predicted that House Wrens should respond to egg removal by laying extra eggs but should not respond to egg addition, while European Starlings should both increase clutch size in response to removal and decrease clutch size in response to addition of eggs. We manipulated clutch size at 70 House Wren and 49 European Starling nests by adding or removing two eggs during the laying period. In early wren clutches, birds altered clutch size as predicted: wrens with nests from which eggs were removed had larger clutches than did control birds, while birds with nests to which eggs were added had clutches of the same size as control birds. However, in late clutches wrens did not respond to either egg removal or addition. Starlings showed no significant response to either egg removal or addition in spite of high rates of conspecific egg removal and brood parasitism within the study population.

Reproductive interactions of the Shiny Cowbird Molothrus bonariensis and the Yellow‐hooded Blackbird Agelaius icterocephalus in Trinidad

The reproductive interactions of the Shiny Cowbird Molothrus bonariensis, a brood parasite, and the Yellow‐hooded Blackbird Agelaius icterocephalus, a host of the cowbird, were studied In Trinidad, West Indies. We gathered information on the breeding biology of the Shiny Cowbird and the Yellow‐hooded Blackbird, the frequency of use of the host species, and the effects of brood parasitism on host breeding success. Yellow‐hooded Blackbirds are polygynous for the most part; males build nests and attempt to attract females to lay in them by means of song and visual displays directed towards the nests. This behaviour probably makes it easy for cowbirds to locate breeding birds and their nests. Cowbird eggs were found in 153 of 377 (40–3 %) blackbird nests located before the nestling stage. Shiny Cowbird parasitism of the Yellow‐hooded Blackbird had little negative impact on host reproductive success, whereas predation accounted for the majority of nest failures. Vigilant nest defense by male blackbirds combined with colonial breeding apparently also minimized the extent of host egg damage and removal by cowbirds, and the parasitized and unparasitized nests were equally successful at producing blackbirds. Cowbirds most frequently parasitized the first or only nesting attempts in blackbird territories, and first or only nests were also successful more frequently than subsequent nests.

Removal of an intra-abdominal egg from a chicken.

Removal of an intra-abdominal egg from a chicken.

Broodcare or Egg Cannibalism by Parents and Helpers in Neolamprologus brichardi (Poll 1986) (Pisces: Cichlidae): a Study on Behavioural Mechanisms

AbstractIn the cichlid species N. brichardi the young are tended by parent animals and broodcare helpers. No qualitative differences in the care are apparent. The regulation of eggcare by nonreproductive helpers is of especial interest as it excludes an endogenous component found in the parental care of other cichlids, based on sex and the reproductive cycle.The importance of the factors dominance, territory, size (age) experience, model and the continuous presence of eggs for helper eggcare disposition was examined experimentally. It was shown that subdominant inexperienced young fish will clean clutches, whereas dominants feed on them. Subdominant eggcleaners can be transformed into dominant eggfeeders; the change can be delayed or prevented by the continuous presence of eggs. Subdominant fish in a territory are more inclined to clean clutches than those in an aggregation. With growing experience (or size) helpers orient broodcare behaviour increasingly by a dominant model. Dominance and experience play no part however in broodpairs; here there are sex‐dependent differences. In both sexes, eggcaring behaviour can be evoked only at the beginning of a breeding cycle. The disposition is bolstered by the presence of the clutch, and wanes after egg removal in females faster than in males. The tendency to continue eggcare can be strongly extended in both sexes by the continuous presence of eggs. Comparison with other cave‐breeding cichlids showed that parental eggcare in these and N. brichardi was similarly regulated. Helper broodcare, however, is very differently regulated. These differences are discussed, as well as possible conclusions on the influence of endogenous and exogenous regulatory factors.

Family Planning in the Kestrel (Falco Tinnunculus): the Proximate Control of Covariation of Laying Date and Clutch Size

Abstract The time in spring when a male kestrel rapidly increases his daily hunting time and his hunting yield, and thereby the amount of food delivered to the female, determines the date when she lays the first egg. Food experiments in free-living and captive kestrels gave a significant advance in laying date. Clutch size, which decreases with progressive laying date, did not change independent of date in response to food manipulation. These effects are in agreement with most other feeding experiments. Photoperiod experiments in kestrels advanced the reproductive cycle in constant long days, and a similar seasonal decline in clutch size was found. It seems that there is an internally preprogrammed decrease in clutch size within an annual "reproductive window". A proximate control model for the seasonal decline of clutch size is proposed, modified from an earlier model by HAFTORN (1985). This incorporates an increasing tendency to incubate the first eggs with progression of the season, an egg contact-incubation positive feedback loop, and the resorption of further follicles in the ovary when the laying female incubates 50% of the time. This follicle resorption fixes the clutch size ca. four days before the last egg is laid. the 50% incubation level is reached earlier in late females and consequently resorption starts earlier and the resulting clutch is smaller than in early females. Experiments in kestrels with removal and addition of eggs, in combination with measurements of incubation behaviour are discussed in relation to the model. Plasma prolactin data of female kestrels show that this hormone is a serious candidate for a physiological component relaying time of year in our model for clutch size regulation.

Effets d'un stockage sur les caracteristiques physico‐chimiques, microbiologiques et parasitologiques de boues biologiques

Abstract Biological sludges stored for 4 months in a silo under oceanic climate, showed a limited maturation with a loss of dry solids and an increase of ammonia nitrogen availability. The die off rate of the fecal indicator organisms (except sulphate reducing clostridia) and Salmonella, was higher than the removal rate for enteroviruses and parasite eggs. A low viral contamination (20 UFP 1−1) remained whatever the season. If there was removal of ancylostoma eggs, storage had little effect on coccidium and amoeba cysts removal.

Egg removal and intraspecific brood parasitism in the European starling (Sturnus vulgaris)

From 1983 to 1986 we monitored 284 European starling (Sturnus vulgaris) nests in New Jersey for evidence of intraspecific brood parasitism and egg removal during the laying period. Egg removal occurred significantly more often at nests where intraspecific brood parasitism was detected (12 of 35 nests, 34%) than at unparasitized nests (23 of 249 nests, 9%). Brood parasitism (92% of parasitized nests) and egg removal (74% of nests with egg removal) were most common at nests where egg laying began in April of each year (i.e., early nests). Egg removal occurred at 26 (19%) and brood parasitism at 32 (23%) of 138 early nests. Both brood parasitism and egg removal were concentrated during the first four days in the laying period when brood parasitism is most likely to be successful and when host nests are most vulnerable to parasitism (Romagnano 1987). Both parasitism and removal usually involved a single egg at each nest. We detected brood parasitism and egg removal on the same day at five of 12 nests (42%) where both were observed. Because starlings do not remove foreign eggs from their nests once they begin laying (Stouffer et al. 1987) we hypothesize that parasite females sometimes removed host eggs while parasitizing nests.

Adaptations of meadow pipits to parasitism by the common cuckoo

The meadow pipit Anthus pratensis is one of the most frequent hosts in Europe parasitized by the common cuckoo Cuculus canorus. The cuckoo normally removes one or more of the host eggs and replaces them with one of its own. The aim of the present study, which was conducted in an upland area of Central Norway, was to test the following question: assuming the cuckoo has laid a mimetic egg (which is slightly larger than and slightly different in color from that of a meadow pipit egg), under what circumstances are the parent meadow pipits able to detect such parasitism? The reaction of the meadow pipits to artificial parasitism was tested. Plastic model cuckoo eggs were used that bore a striking resemblance to real cuckoo eggs found in other meadow pipit nests in the same area. In addition, in some experiments a stuffed cuckoo dummy was used. The meadow pipits tolerated the experimental procedures and remained in their nests when given an artificial cuckoo egg, with or without removal of one of the host's eggs. However, when a host egg was removed and replaced with an artificial cuckoo egg, and at the same time a stuffed cuckoo dummy was presente, 50% of the birds deserted their nests. The difference between this result and the results of the other experiments was statistically significant. When only the stuffed cuckoo was presented, without any egg manipulations, the meadow pipits reacted in the same way as in the egg experiments. We conclude that the meadow pipit is capable of detecting whether or not its nest has been parasitized, provided it has observed the cuckoo near the nest site. Furthermore, because of the results of our experiments, we reject the hypothesis that the cuckoo has evolved egg removal behavior in order to prevent the host from assessing an increase in egg numbers.

Nesting, Renesting, and Manipulating Nesting of Florida Sandhill Cranes

Mean laying date of 53 Florida sandhill crane (Grus canadensis pratensis) nests during 1983-87 was 12 March. Mean clutch size for 99 nests was 1.72. Clutch size was not affected by laying date or clutch sequence. Seventy-eight percent of pairs that abandoned or had eggs removed from first or second nests renested; 38% of nests hatched successfully. Intervals between clutches were 18-20 days, irrespective of laying date or the number of days of incubation that preceded nest loss. Nest incubation during daylight hours was shared equally by males and females but was not uniformly distributed throughout the day. Removal of eggs was an effective method of prolonging nesting; however, it would be impractical to use egg removal to synchronize laying dates as part of a large-scale cross-fostering effort. J. WILDL. MANAGE. 52(4):758-763 A cross-fostering study conducted in the Rocky Mountain states revealed that sandhill cranes can foster-rear whooping cranes (Grus americana) and the adopted offspring will migrate along the route used by their foster parents (Drewien and Bizeau 1978). The success of this approach and the existence of a substantial population of nonmigratory sandhill cranes in Florida (Williams 1978) prompted an investigation into the possibility of and methodology for developing a nonmigratory population of whooping cranes in Florida similar to one that existed in Louisiana until the 1940's (Lowery 1974). No nonmigratory whooping cranes exist today; consequently, a study to predict the migratory propensity of a migratory species fosterreared by nonmigratory parents was undertaken in 1981 with greater sandhill cranes (G. c. tabida) as surrogates for whooping cranes (Nesbitt 1982). A problem with this approach that became apparent early in the study was the difference in laying dates between Florida sandhill cranes and greater sandhill cranes, and more importantly, whooping cranes in the wild or in captivity. There may be several ways to circumvent this problem: the photoperiod could be artificially manipulated to hasten egg production in captive cranes, or nesting of candidate, wild, foster parents could be prolonged. To establish nonmigratory whooping cranes using Florida sandhill cranes as foster parents in Florida, we needed an understanding of nesting biology of the resident subspecies. Prior knowledge of peak egg-laying dates, mean clutch size, renesting tendency, interval between clutches, nest attentiveness, and differences in nest attentiveness between sexes would aid in establishment and management of a nonmigratory flock anywhere in the southern United States. Published information on nesting of Florida cranes has come primarily from southcentral Florida. Walkinshaw (1949, 1973, 1976, 1982), Thompson (1970), and Bishop and Collopy (1987) described nests and nesting habitat. Walkinshaw (1985) also described nest attentiveness of male and female Florida sandhill cranes and greater sandhill cranes (Walkinshaw 1965a). Littlefield and Ryder (1968) presented additional information on nesting behavior of color marked male and female greater sandhill cranes in Oregon. The purpose of my study was to evaluate the possibility and best method of prolonging nesting in wild Florida cranes and gain greater understanding of their nesting biology. I appreciate the Florida Department of Natural Resources, Division of Parks and Recreation, for providing access to Paynes Prairie. F. M. and T. J. Cone, C. L. Brice, and H. M. and J. Z. Chitty allowed access to their property. Field assistance was provided by A. S. Wenner, S. T. Schwikert, and J. H. Hintermister V, R. D. Bjork, and K. S. Williams; their help was crucial to this study. Greater sandhill crane eggs used in Florida came from normal nesting pairs in Wisconsin or from captive pairs at the U.S. Fish and Wildlife Service's Patuxent Research Center in Laurel, Maryland. I am indebted to personnel with the Wisconsin Department of Natural Resources, International Crane Foundation, and Patuxent Wildlife Research Center. Financial support was provided, in part, by the U.S. Fish and Wildlife Service Endangered and Threatened Species Program.