Egg Loss Research Articles

Role of gamete limitation in the occurrence of ‘abnormal early clutches’ on female American lobster, Homarus americanus, in eastern Canada

A large-scale survey in 2011–2014 found that ovigerous female American lobsters, Homarus americanus, carrying “abnormal” early clutches (< 50% of abdomen covered by eggs) were ubiquitous in eastern Canada. This could be caused by reduced production of oocytes, or insufficient sperm to fertilize all oocytes produced. To address the oocyte limitation hypothesis, ovarian fecundity was assessed in 343 pre-spawn females and clutch fecundity in 169 post-spawn females sampled from ten sites across eastern Canada in May and June 2014. All females produced and spawned enough oocytes to form a full clutch, thus invalidating the oocyte limitation hypothesis. To address the sperm limitation hypothesis, the prevalence of different “types” of sperm plug in the seminal receptacle of 1735 wild-mated, pre-spawn or ovigerous females was surveyed in July–August 2014 and 2015, and the effect of sperm plug type on fecundity/fertility was examined in 60 wild-mated, laboratory-spawning females beginning in July 2014. Among the pre-spawn wild-mated females, 88.3% had a hard plug, 5.9% a soft plug and 5.8% no plug. These sperm plug types corresponded to sharply decreasing amounts of stored semen/sperm in post-spawn females. In the laboratory, 11 of 20 females with no plug produced a full clutch that became “abnormal” through egg loss or was completely dropped within 2 weeks of spawning. Thus, sperm limitation is one likely cause of abnormal early clutches on female American lobster, which may be occasioned by fishery-induced reductions in male reproductive potential and/or density-dependent processes occurring at currently high population levels.

Impact assessment of dredging on fish eggs and larvae: A case study in Caotan, South China

Dredging can lead to an increase in suspended sediment concentration, which poses a threat to the survival of fish eggs and larvae.To assess the impact of dredging on fish eggs and larvae, Caotan Fishing Port in south China was chosen as a case in this paper. The threat to the survival of fish eggs and larvae, i.e. the increased suspended sediment concentrations, is identified through analyzing pollution sources in dredging operations; the number and species of fish eggs and larvae were obtained through on-site investigations; the concentration and influence range of suspended sediments are calculated by pollutant diffusion equations; the loss of fish eggs and larvae caused by suspended sediment during dredging is evaluated according to Technical Regulations for the Impact Assessment of Construction Projects on Marine Biological Resources (SC/T 9110-2007) in this paper. It can be preliminarily concluded that the suspended sediments produced during dredging and backfilling have an impact on the survival of fish eggs and larvae, and will reduce their quantity. Currently, loss analysis methods are based on empirical formulas, and more accurate quantitative analysis needs to be further studied.

Sulfate and hydroxychloride trace minerals in poultry diets – comparative effects on egg production and quality in laying hens, and growth performance and oxidative stress response in broilers

ABSTRACTTwo experiments investigated the effect of sulfate and hydroxychloride trace minerals (TM), Zn, Cu, and Mn, in laying hens and broiler chickens. In Expt. 1, Lohmann Brown pullets (total of 1,344) at 21 wk of age were used for a 24-wk experiment. Each of the two treatments had 32 replicates with 21 hens per replicate. At 45 wk of age, three eggs per cage were randomly selected and used for internal quality assessment. In Expt. 2, Ross 308 broilers (total of 1,080) were allocated to two treatments. Each treatment had 30 replicates with 15 chicks per replicate. On day 28, after weighing, three birds were randomly selected from 15 randomly selected pens per treatment. The birds were euthanized and blood was collected for analysis for uric acid, C-reactive protein and methylmalonic acid. Samples were also taken from pectoralis muscle of each chicken and analyzed for mRNA expression of protein synthesis or hydrolysis genes. On day 35, 7 birds per pen were used for carcass evaluation. In Expt. 1, egg weight was greater (P < 0.01) in birds receiving sulfate TM from week 16 (of experiment) onwards whereas the percentage of cracked eggs was lower (P < 0.01) in hens receiving hydroxychloride TM. Percentage hen-day production tended to be greater (P < 0.10) in hens receiving hydroxychloride TM in weeks 4 to 8 only. In Expt. 2, birds receiving hydroxychloride TM had greater (P < 0.05) weight gain and tended to have greater (P < 0.10) feed intake on day 35. Expression of the gene, PSMA1, was lower (P < 0.05) whereas plasma level of uric acid and methyl malonic acid tended to be lower (P < 0.10) in birds receiving hydroxychloride TM. It was concluded that hydroxychloride TM reduced egg loss in hens at peak production and that improved growth performance response in broilers can be partly explained by reduction in proteolytic activities in the pectoralis muscle and greater resilience to oxidative stress.

Effects of rice protein coatings combined or not with propolis on shelf life of eggs.

Although eggs are an excellent protein source, they are a perishable product. Many methods exist to extend shelf life of food and one of them is the use of protein coatings that may be combined with antimicrobial substances, as propolis. The effectiveness of rice protein coatings plus propolis on maintaining interior quality and eggshell breaking strength of fresh eggs was evaluated during storage at 20°C for 6 wk. Egg quality was assessed by weight loss, Haugh unit (HU), albumen pH, yolk index (YI), shell strength, and scanning electron microscopy in uncoated eggs (control treatment) and eggs coated with rice protein concentrate and propolis at 5 or 10%. The HU and YI were higher in coated eggs (P < 0.001). Weight loss increased (P < 0.001) during long-term storage. Uncoated eggs showed the highest weight loss (5.39%), whereas rice protein (4.27%) and rice protein plus propolis at 5% (4.11%) and 10% (4.40%) solutions were effective in preventing weight lost (P < 0.001). Uncoated eggs had the worst (P < 0.001) HU (58.47), albumen pH (9.48), and YI (0.33) after 6 wk of storage. The eggs coated with rice protein and rice protein plus propolis presented results with similar intern quality between them during all the storage period. Scanning electron microscopy demonstrated a lower surface porosity in coated eggshell, indicating that the use of the coating may provide a protective barrier against the transfer of gases and moisture. In conclusion rice protein and propolis treatments helped to maintain egg quality for a longer time compared to uncoated eggs. These could be a viable alternative for maintaining the internal quality of fresh eggs during long-term storage at room temperature.

An evaluation of nest predator impacts and the efficacy of plastic meshing on marine turtle nests on the western Cape York Peninsula, Australia

Nest predation is considered to be one of the most significant biotic threats to marine turtle populations globally. The introduction of feral predators to nesting beaches has dramatically increased nest predation, reaching near total egg loss in some regions. We monitored a 48 km stretch of beach along western Cape York Peninsula, Australia, from June – November 2018. We recorded a total of 360 nests comprising 117 flatback and 243 olive ridley nests. We installed plastic meshing (90 cm × 100 cm) on 110 olive ridley nests (45.2% of total olive ridley clutches laid) within the study area. We classified all nest predation attempts into three categories: complete, partial, or failed predation events. In total, 109 (30.2%) of all marine turtle nests were depredated by a variety of predators, including feral pigs, dingoes, goannas, and humans. The addition of plastic meshing reduced the likelihood of dingoes gaining access to eggs, but not goannas or feral pigs. Further, we found no difference in the proportion of hatchling emergence between meshed and un-meshed nests. Additionally, while hatchling emergence was reduced in nests that had been partially depredated, these nests still produced live hatchlings and contributed to recruitment. The success of particular predator control methods is often predator, and/or regionally, specific. Our findings highlight a thorough understanding of predator guilds and their relative impacts is required to deploy targeted and predator-specific strategies to maximize conservation results. We present a strong case for data-driven adaptive management that has implications for designing optimal predator management plans.

Revisiting the influence of aggressive interactions on the survival of the first‐laid egg in crested penguins (genus Eudyptes)

Crested penguins Eudyptes spp. have evolved a unique form of breeding in which the first of two eggs laid is much smaller than the second and has a higher likelihood of being lost during egg laying and incubation. In this study, we quantified aggressive behaviour in nesting Snares penguins and undertook an egg survival analysis to examine which factors influence egg loss. During 120 h of observation of 50 nests, we recorded a total of 300 aggressive events in which females were repeatedly pecked, bitten and beaten. Aggressive events lasted from less than a minute to up to 55 min (mean 4.6 ± 7.4 min). Single males were the aggressor in 75% of aggressive events and in 50.7% of aggressive events the aggressor was identified as a neighbouring, breeding male. A greater percentage of the small first eggs (34%) were lost than the large second eggs (4%). We found that egg mortality was influenced by 1) whether the other egg within a nest had hatched, 2) who was present at the nest (father, mother or both) and 3) the average duration of aggressive events on the nest. When one egg within a nest had hatched, the other egg had a vastly increased mortality risk irrespective of aggression. However, long, aggressive events directed towards females after their partners had gone foraging, also increased the probability of egg loss. We suggest that the prolonged nest attendance by breeding males well beyond egg laying is in response to the high frequency of aggressive behaviour during this time. Our data show that A‐egg losses occur due to intraspecific aggression in this species. Further research is needed to clarify whether aggressive behaviour in breeding crested penguins is modulated by elevated testosterone levels in the males and whether any reproductive benefits accrue to the aggressors.

Low-dose of organic trace minerals reduced fecal mineral excretion without compromising performance of laying hens.

ObjectiveThe objective of this study was to investigate the effects of low doses of organic trace minerals (iron, copper, manganese, and zinc) on productive performance, egg quality, yolk and tissue mineral retention, and fecal mineral excretion of laying hens during the late laying period.MethodsA total of 405 healthy hens (HY-Line White, 50-week-old) were randomly divided into 3 treatments, with 9 replicates per treatment and 15 birds per replicate. The dietary treatments included feeding a basal diet + inorganic trace minerals at commercial levels (CON), a basal diet + inorganic trace minerals at 1/3 commercial levels (ITM), and a basal diet + proteinated trace minerals at 1/3 commercial levels (TRT). The trial lasted for 56 days.ResultsCompared to CON, ITM decreased (p<0.05) egg production, daily egg mass, albumen height, eggshell strength, yolk Fe concentration, serum alkaline phosphatase activity and total protein, and increased (p<0.05) egg loss and feed to egg ratio. Whereas with productive performance, egg quality, yolk mineral retention, and serum indices there were no differences (p>0.05) between CON and TRT. The concentrations of Fe and Mn in the tissue and tibia were changed notably in ITM relative to CON and TRT. Both ITM and TRT reduced (p< 0.05) fecal mineral excretion compared to CON.ConclusionThese results indicate that dietary supplementation of low-dose organic trace minerals reduced fecal mineral excretion without negatively impacting hen performance and egg quality.

A Non-Invasive Method to Reduce the Negative Impact of Black-Headed Gulls Chroicocephalus ridibundus on the Breeding Success of Common Terns Sterna hirundo

Two or three gull species (Laridae) commonly breed together in one colony, often caused by a shortage of optimal breeding sites or as an anti-predator behaviour. Observers usually assume that the benefits of colonial breeding outweigh potential costs. Still, our study shows that the costs can be substantial. We show that short distances between nests of Black-headed Gulls and Common Terns breeding in a colony often lead to aggressive interactions between these birds in which terns lose eggs during laying and incubation. We created a buffer zone between the nests of terns and gulls to reduce losses in the terns' clutches. All nests of Black-headed Gulls closer than 120 cm to nests of Common Terns were gradually moved away over 1–4 consecutive days, reducing the terns' egg losses by almost six times. Our results show that our method was safe for both species, and is non-invasive, cheap and easy. This conservation measure could be used in those regions of Europe and North America where breeding Common Terns are declining and perhaps globally in other mixed Larid colonies where species are under threat.

Nesting success and productivity of the Common Barn-owl Tyto alba: results from a nest box installation and long-term breeding monitoring program in Southern Hungary

Abstract In this study, the results of a long-term nest box installation program of the Common Barn-owl Tyto alba (Scopoli, 1769) in Southern Hungary were evaluated, which program was conducted during a 24-year period (1995–2018). The percentages of occupied nest boxes ranged from 9.72 to 73.44% in the first breeding periods while this varied between 0 and 41.46% in the case of repeated clutches in the same nest boxes with second broods. A total of 1,265 breeding attempts were recorded including 1,020 (80.63%) in the first and 245 (19.36%) in the second breeding periods, from which a total of 210 (16.6%) clutches did not produce any fledglings. The modal clutch size was 7 eggs in both first and second annual clutches. However, the value of productivity was higher in the case of larger clutch sizes and we found significant linear relationship between initial clutch size and fledgling production per nesting attempt in both breeding periods. Significant variation of reproductive parameters was observed among the years. The proportion of egg loss showed significant decline, while the change of hatching success and the variation of annual productivity showed significant slight positive linear trend during the 24 years. Our results suggested that despite the outlier values of reproduction characteristics in the extreme years with negative effect, a relatively stable Common Barn-owl population can be maintained by the placement of nest boxes in the investigated region.

Fisheries-related variations in the fecundity of the southern king crab in Patagonia

The southern king crab (SKC) Lithodes santolla has supported a profitable fishery in the San Jorge Gulf (SJG) and adjacent area, Argentina, since 2004. This fishery allows landings only of males larger than 110 mm carapace length. Since large-male-only harvests have had a detrimental effect on the egg production of other king crab populations, here, we compared the SKC fecundity before the start of the industrial fishery (1994–1996) with that of the fully harvested population (2014–2018), and analyzed the variation in fecundity related to fishery policies, to areas with different levels of fishing effort, and to different times of the fishing season. During 2014–2016, SKC fecundity was 25% lower than that during the pre-fishery period (1994–1996). However, fecundity in 2017–2018 was 11% lower than that during the pre-fishery period. Results also revealed that fecundity was greater in coastal areas (where an artisanal fleet operates) than in offshore areas (where the industrial fleet operates) and that it was similar throughout the fishing season. We concluded that: 1) SKC fecundity decreased after 10 years of fishing, 2) fishing during the mating period affected SKC fecundity, and 3) there is no significant egg loss during the fishing season. Recent changes in SKC fishery management, including the mandatory use of escape rings and the implementation of a closure during mating, seem to have had a positive effect on SKC fecundity.

Habitat Type Influences Danaus plexippus (Lepidoptera: Nymphalidae) Oviposition and Egg Survival on Asclepias syriaca (Gentianales: Apocynaceae)

As agricultural practices intensify, species once common in agricultural landscapes are declining in abundance. One such species is the monarch butterfly (Danaus plexippus L.), whose eastern North American population has decreased approximately 80% during the past 20 yr. One hypothesis explaining the monarch's decline is reduced breeding habitat via loss of common milkweed (Asclepias syriaca L.) from agricultural landscapes in the north central United States due to the adoption of herbicide-tolerant row crops. Current efforts to enhance monarch breeding habitat primarily involve restoring milkweed in perennial grasslands. However, prior surveys found fewer monarch eggs on common milkweed in grassland versus crop habitats, indicating potential preference for oviposition in row crop habitats, or alternatively, greater egg loss to predation in grasslands. We tested these alternative mechanisms by measuring oviposition and egg predation on potted A. syriaca host plants. Our study revealed that habitat context influences both monarch oviposition preference and egg predation rates and that these patterns vary by year. We found higher monarch egg predation rates during the first 24 h after exposure and that much of the predation occurs at night. Overall, we documented up to 90% egg mortality over 72 h in perennial grasslands, while predation rates in corn were lower (10-30% mortality) and more consistent between years. These findings demonstrate that weekly monarch egg surveys are too infrequent to distinguish oviposition habitat preferences from losses due to egg predation and suggest that monarch restoration efforts need to provide both attractive and safe habitats for monarch reproduction.

Investigating fecundity and egg loss using a non-invasive method during brooding in European lobster (Homarus gammarus)

AbstractThis article examines two important components of measurement of fecundity in the European lobster Homarus gammarus: (i) comparing the traditional gravimetric dry weight fecundity method against two non-invasive depth gauge methods initially developed for Homarus americanus and (ii) utilizing the depth gauge method to determine egg loss during the brooding period and its impacts on effective fecundity estimates. No significant difference was observed between fecundity estimates derived using either the traditional or depth gauge methods. Derived fecundity estimates from the two depth gauge methods differed by −0.31% (±2.7 s.e.) for cylinder and −1.1% (±2.4 s.e.) for ellipsoid fecundity estimates compared with the traditional method. This highlights the utility of the depth gauge method for providing fast, reliable and low-cost estimates without sacrificing lobsters or their egg masses. Egg loss is estimated to be as high as 44% from initial extrusion to hatching. The application of the non-invasive methods for estimating fecundity to other fisheries and stocks is discussed along with the importance of understanding egg loss in this commercially valuable fishery.

Investigating fecundity and egg loss using a non-invasive method during brooding in European lobster (Homarus gammarus)

Investigating fecundity and egg loss using a non-invasive method during brooding in European lobster (Homarus gammarus)

Rice protein coating in extending the shelf-life of conventional eggs

The effectiveness of rice protein coatings or mineral oil on maintaining interior quality and eggshell breaking strength of fresh eggs was evaluated during storage at 20°C for 8 wk. Egg quality was assessed by weight loss, Haugh unit (HU), albumen pH, yolk index (YI), shell strength, and scanning electron microscopy in uncoated eggs (control treatment) and eggs coated with mineral oil or rice protein concentrate at 5, 10, or 15%. The HU and YI were higher in coated eggs (P < 0.001). Weight loss increased (P < 0.001) during long-term storage. Uncoated eggs showed the highest weight loss (8.28%), whereas mineral oil (0.87%) and rice protein at 5% (5.60%), 10% (5.45%), 15% (5.54%) solutions were effective in preventing weight lost (P < 0.001). The use of the coatings preserved the internal quality of the eggs for up to 4 wk longer than uncoated eggs (HU, YI, and pH). Uncoated eggs had the worst (P < 0.001) HU (54.45), albumen pH (9.18), and YI (0.28) after 8 wk of storage. Among the coated eggs, the mineral oil had the best values of HU (70.54), pH (8.48), and YI (0.35) after storage. The eggs coated with 5, 10, and 15% of rice protein presented results with similar intern quality between them and intermediary quality in relation to the others treatments during all the storage period. Scanning electron microscopy demonstrated a lower surface porosity in coated eggshell, indicating that the use of the coating may provide a protective barrier against the transfer of gases and moisture. In conclusion, the use of coatings based on rice protein concentrate or mineral oil influences the internal quality of eggs during storage and may be an effective alternative for increasing the shelf-life of commercial eggs.

Laboratory evaluation of spawning substrate type on potential egg predation by round goby (Neogobius melanostomus)

Spawning habitat structure may protect demersal eggs of broadcast spawning species from depredation. Egg predation by round goby (Neogobius melanostomus) is commonly referenced as a concern associated with their invasion of the Laurentian Great Lakes. Whereas nest-building species have received some attention in egg predation studies, broadcast spawning species may be particularly vulnerable as they do not guard their eggs. This study used a 2 × 7 factorial experiment to investigate how substrate characteristics influenced the rate that fertilized eggs are lost when exposed to round goby. Eggs for two recreationally important broadcast spawning species, northern pike (Esox lucius) and muskellunge (Esox masquinongy), were placed within spawning habitat treatments (bare, silt, sand, rubble, gravel, filamentous algae, and submerged aquatic vegetation) representing a range (least to most complex) of habitat complexity. Regardless of substrate type, egg loss was similar between the two esocid species. Across all substrates and species, the number of eggs lost varied two-fold over the 24-hour experiment, with the lowest rate of egg loss observed in the most complex substrate (submerged aquatic vegetation) and the highest over the least complex substrates (bare and silt). Both northern pike and muskellunge are known to spawn over structurally complex submerged aquatic vegetation and filamentous algae. Although eggs spawned over these substrates likely offer some protection from predation, eggs that settle over less complex ancillary habitats may face higher predation risk.

Predation on Eggs of Aedes aegypti (Diptera: Culicidae): Temporal Dynamics and Identification of Potential Predators During the Winter Season in a Temperate Region.

In temperate regions, the populations of Aedes aegypti (L.) remain in the egg stage during the cold season. The ability of these eggs to survive until the next favorable season is affected by several mortality factors, including the action of predators. In the present study, we analyzed the temporal dynamics of the loss of eggs and identified predators of Ae. aegypti eggs along the unfavorable season in a temperate region of Argentina. To this end, eggs were exposed in field conditions in pitfall traps, where walking arthropod taxa were captured during 1-wk periods from early June to early September (Austral winter). The association of arthropod taxa with the loss of eggs was analyzed to identify potential predators. Based on the results obtained, two taxa were chosen to confirm their capacity to consume eggs in a laboratory study. The proportion of lost eggs and the abundance of predators were significantly higher in the winter-spring transition, although results were heterogeneous among traps in all exposure periods. Ants of the genus Strumigenys, isopods of the species Armadillidium vulgare (Isopoda: Armadilloidea), and dermapterans of the species Euborellia annulipes (Dermaptera: Anisolabidae) were positively associated with a high proportion of lost eggs. In laboratory conditions, A. vulgare and E. annulipes consumed the offered eggs, thus confirming their predator capacity. This study represents the first record of predation of Ae. aegypti eggs in temperate South America and the first evidence of dermapterans consuming mosquito eggs.

Effects of The Dietary Supplementation of Layer Diets with Natural and Synthetic Antioxidant Additives on Yolk Lipid Peroxidation and Fatty Acid Composition of Eggs Stored at Different Temperatures and Duration

ABSTRACT In this study, the effects of the supplementation of natural and synthetic antioxidant additives in layer diets on egg weight loss, yolk lipid peroxidation (TBARS values) and fatty acid composition of eggs stored at different temperatures and duration were evaluated. In total, 112 48- weeks-old Bovans White layers were randomly allotted to four dietary treatments with four replicates of seven birds each. The treatments consisted of a control diet, containing no additives, and diets with the inclusion of 200 mg synthetic vitamin E/kg, 1000 mg thyme extract/kg and 1000 mg rosemary extract/kg. Dietary treatments did not influence (p>0.05) relative weight loss of eggs stored for 14, 28, and 56 days, except for those from rosemary-fed hens stored at room temperature on d 42, which were significantly lighter than the eggs from vitamin E- and thyme-fed hens (p 0.05) of dietary treatment on yolk TBARS values were detected in refrigerated eggs. The inclusion of the synthetic and both natural antioxidants in layer diets significantly reduced stearic acid (C18: 0) level in the egg yolk. In addition, only natural antioxidants significantly increased yolk levels of palmitoleic acid (C16: 1) and vaccenic acid (C18: 1n7). The results of the present study showed that adequate storage temperature was more effective in improving egg shelf life than feeding layers synthetic or natural antioxidant additives. However, the positive effects of the evaluated natural antioxidants on yolk fatty acid composition suggest their supplementation to layer diets may provide health benefits to the consumer.

Low light intensity in Pekin duck breeder barns has a greater impact on the fertility of drakes than hens

The Pekin duck is an excellent model for the study of seasonal reproduction. To more completely understand the lighting requirements for maximal fertility in duck breeder houses, we housed adult (45 week old) drakes and hens in the Hope College aviary as 5 drakes and 25 hens. Light conditions in each floor pen were normalized based upon quantal energy and divided into the following categories: (1) to simulate summer, 14.5h 65 lux with 9.5h 1 lux; (2) to simulate winter, 8h 65 lux with 16 h 1 lux; (3) winter augmented, 8h 65 lux with 16 h at 15 lux. The experiment was repeated with rotation of light treatments among 3 pens until a final N = 6 was obtained. Daily, total number of eggs laid was tallied, and a daily average of eggs laid was calculated throughout the study. Weekly, eggs were weighed and the perivitilline membrane was assayed for the number of sperm holes as an indirect measure of drake fertility. As expected, winter conditions caused a reduction in the percent of eggs laid and a reduction in the number of fertilized eggs compared to the summer light conditions. The augmented winter light conditions prevented the loss in the percent eggs laid and fertilized eggs. Surprisingly, even after 4 wk of the study, the winter conditions did not cause a complete loss of fertility in the Pekin ducks. At the end of the study, no differences in the relative expression in brain deep brain photoreceptors or gonadotropin inhibitory hormone mRNAs were observed among any light treatment. Although a minimum (1 lux) of light can support some fertility, our findings suggest commercial Pekin duck barns may benefit from increasing the augmented light to 15 lux to maintain optimal fertility during winter months. Furthermore, our data suggest that drakes may be more sensitive to environmental light conditions than hens.

Capturing Crows for the Protection of Threatened and Endangered Shorebird Species

ABSTRACTCorvids are highly intelligent and capable of thriving in anthropogenic ecosystems. American crows (Corvus brachyrhynchos) regularly depredate threatened and endangered avian species. Live capture is a common component of crow management programs; however, crows are notoriously difficult to capture. Here, we report previously undocumented crow capture techniques, utilizing a modified goshawk (Accipiter gentilis) trap design as part of a shorebird conservation project in San Diego, California, USA, 2012–2017. A negative binomial generalized linear model showed a significant relationship between number of crows removed and number of endangered California least tern (Sternula antillarum browni) eggs predated by crows. Of the total number of crows in that analysis, 67% were removed via goshawk trap. Therefore, we attribute the same percentage of reduction in egg loss to the success of that trap type. We tested 2 goshawk trap designs that differed by number of capture chambers (single and double). Double‐chambered traps were nearly twice as effective at capturing crows compared with single‐chambered traps. We performed McNemar's χ2 tests with continuity correction to determine whether traps were more effective with the use of conspecific lure‐birds and obtained significant results for single and double‐chambered traps. The modified goshawk trap has an efficient design that can improve crow control programs, especially when constructed with 2 chambers and deployed with lure‐birds. © 2018 The Wildlife Society.

Effect of non-conventional storage methods on external and internal egg qualities

To know and identify the traditional practices and generate relevant information on egg storage methods, a survey work was conducted in the East Wollega Zone of Ethiopia. The survey was carried out with a stratified sampling technique and a structured questionnaire using a total of 315 households (225 from rural and 90 from urban owning chickens) were purposefully selected. Two experiments, of similar experimental materials, procedures and designs were conducted at different time of the year (May and August) to evaluate these traditional storage methods at Haramaya University poultry farm. A factorial experiment of 2 by 5 with completely randomized design using storage containers and storage time as treatment was used. The storage times were 4, 6, 8, 12 and 20 days. Five most common egg storage containers were identified in the rural and urban areas of East Wollega. These storage methods include cartons, polyethen bags, baskets, clay pots and teff grain. The result further indicated that depending on the availability of the storage materials in the locality, 87 percent of the urban households (n = 90) store eggs in cartons and polyethene bags in order of availability. Seventy nine percent of the rural households (n = 225) ranked teff as the most common storage materials used followed by the basket and clay pots. Among the quality parameters considered, weight loss (%) and daily weight loss (%) of eggs were highly affected (P < 0.001) by storage containers, durations and their interactions during both experiments. The maximum weight loss was observed after storage period of 16 days for all containers. Polythene bags storage maintained minimum weight loss Vs the baskets at all stages of storage duration. Only storage durations had significant effects (P < 0.05) on the egg shell thickness during experiment I. Inconsistent but significant effect of storage durations was observed on the shell weight during experiment I, and weights of yolk and albumen during experiment II. Storage containers during experiment I, and storage durations during experiment II showed significant effects on albumen height and haugh unit values. Except polythene bags which had higher albumen height and haugh unit values, the other containers did not show significant variations for both parameters. The effect of storage duration on these parameters was linear with increasing storage duration; and higher beyond the 16 days of storage. Thus, it was concluded that using polyethylene bags and 16 days of storage could give the best result to store eggs among the traditional methods compared in this experiment. Keywords: Traditional Egg Storage; Changes in Egg Quality; Optimum Egg Storage Duration