Vocalizations and courtship displays of the Bittern Botaurus stellaris

Capsule We report on the courtship behaviour of the Eurasian Bittern from direct observation in rice fields.     

Man-induced habitat changes and sensitive species: a GIS approach to the Eurasian Bittern (<Emphasis Type="Italic">Botaurus stellaris</Emphasis>) distribution in a Mediterranean wetland

Modifications to the Massaciuccoli wetland (Central Italy) caused by various human activities were examined in relation to the distribution of the local Bittern (Botaurus stellaris) population. From 1993 to1998 we documented the changing distribution pattern of booming males within the marsh, while at the same time gathering information on human utilisation of the habitat. The evolution of the marsh’s layout overtime has been accurately delineated by developing a Geographical Information System. Local customs of marsh utilisation, in particular the illegal setting of fires and the enlarging of hunting pools, had major impacts on its features. The vegetation beds, dominated by Cladium mariscus, proved to be a patchwork mosaic of different-aged plants (from the last fire or cutting), whose densities therefore increased over time. Booming male distribution was uneven within the marsh and varied from one year to the next. The youngest vegetation beds covered more than 50% of the 50 m-buffer zones defined around booming males. A logistic regression model showed that Bitterns favoured unfragmented young vegetation beds (1–3 years). Consideration of the current state of affairs suggests that the necessary renewal of the vegetation could be best achieved through co-ordinated actions carried out in rotation on predetermined plots, covering at least 20 ha in extent and managed at least every 4 years.     

A new method for catching cavity‐nesting birds during egg laying and incubation

ABSTRACT The physiological condition of female birds during the egg‐laying and incubation periods is of considerable interest and yet is relatively understudied in wild birds, primarily due to the difficulty of catching birds during this period without causing nest desertion. We therefore developed a box‐net to capture cavity‐nesting birds using sections of a mist‐net placed around a metal cubic frame. We captured female Great Tits (Parus major) as they left nest boxes during the egg‐laying and incubation periods and measured desertion rates. Using box‐nets, we captured 108 of 119 (90%) females during egg laying and 10 of 12 (83%) during incubation. Our recapture rate over two consecutive days during incubation was 50% (5 of 10). Females not captured left nest boxes before we attempted to capture them, escaped through a hole in the mist‐net, or remained in nest boxes for more than 2 h, after which we ended capture attempts. Overall, 22% of egg‐laying females deserted, with desertion rates highest early in the egg‐laying period. Desertion rates of females captured using box‐nets did not differ from those of undisturbed females. One of 10 females captured in a box‐net deserted during the incubation period. Box‐nets are portable, can be set up and taken down quickly and easily, and could potentially be used with nest boxes or natural cavities at any height. Box‐nets are easy to construct and adaptable for use with an array of cavity‐nesting birds, and can be an important tool for studying female physiology during egg laying and incubation.     

The hen's fertile egg screening test (HEST): A comparison between the acute toxicity for chick embryos and rodents of 20 drugs

The possibilities of using developing chick embryos for evaluating drug activities and toxicities were studied by determining LD₅₀ values for 20 drugs with 14 different pharmacological activities. Fifteen-day old chick embryos received drugs through the air cell and deaths were measured at 48 hr after the treatments. The LD₅₀ values were determined and compared to the i.v., i.p., s.c. and p.o. values from mice listed in the Registry of Toxic Effects of Chemical Substance. The systemic toxicity of 15-day-old chick embryos to drugs were similar to those of mice with the following exceptions. The chick embryos seemed to be more sensitive than mice to antineoplastic or antibiotic agents such as actinomycin D and doxorubicin, whereas, LD₅₀ values of cholinergic and cholinergic blocking drugs by this method were 10 to 20 fold of LD₅₀ (i.v.) of mice. These observations are important for applying the hen's fertile screening test (HEST) to the determination of drug activities other than that of embryo toxicity or teratogenic activity.Abbreviations i.v. intravenous administration - i.p. intraperitoneal administration - s.c. subcutaneous administration - p.o. oral administration - LD₅₀ acute median lethal dosage     

Effects of experimental calcium availability,egg parameters and laying order on Great Tit Parus major eggshell pigmentation patterns

Many bird species lay eggs speckled with protoporphyrin‐based spots, however, for most of them the function of eggshell spotting is unknown. A plausible hypothesis is that protoporphyrin might have a structural function in strengthening the eggshell and is therefore deposited when calcium is scarce. In this study, we experimentally provided Great Tit Parus major females with supplemental calcium to examine its effect on the protoporphyrin‐based maculation of their eggs. In addition, we studied variation in eggshell pigmentation patterns in relation to other egg parameters and laying order. Calcium‐supplemented females laid larger eggs but shell thickness was not significantly affected by the treatment. Calcium supplementation may reduce the time and energy females devote to searching for calcium‐rich material, so that they can collect more nutrients and so lay larger eggs. Furthermore, pigment darkness was associated with egg volume and shape, which suggests that female quality and environmental food availability may also influence the shell pigmentation pattern. Within clutches, later‐laid eggs had larger and darker spots that were distributed more unevenly on the shell surface. This within‐clutch pattern could be explained by the increase in egg volume and egg shape and a decline in shell thickness with egg‐laying order, which characteristics were all related to shell‐spotting pattern. Eggs with a coronal ring had thinner shells, but pigment intensity and spot size were not related to shell thickness. Thus, our results suggest that concentrated spotting distribution may have a mechanical function, supporting the structural‐function hypothesis.     

Segmental independence and age dependence of neurite outgrowth from embryonic chick sensory neurons

Targets in limb regions of the chick embryo are further removed from the dorsal root ganglia that innervate them compared with thoracic ganglion-to-target distances. It has been inferred that axons grow into the limb regions two to three times faster than into nonlimb regions. We tested whether the differences were due to intrinsic properties of the neurons located at different segmental levels. Dorsal root ganglia (DRG) were isolated from the forelimb, trunk, and hind limb regions of stage 25–30 embryos. Neurite outgrowth was measured in dissociated cell culture and in cultures of DRG explants. Although there was considerable variability in the amount of neurite outgrowth, there were no substantive differences in the amount or the rate of outgrowth comparing brachial, thoracic, or lumbosacral neurons. The amount of neurite outgrowth in dissociated cell cultures increased with the stage of development. Overall, our data suggest that DRG neurons express a basal amount of outgrowth, which is initially independent of target-derived neurotrophic influences; the magnitude of this intrinsic growth potential increases with stage of development; and the neurons of the DRG are not intrinsically specified to grow neurites at rates that are matched to the distance they are required to grow to make contact with their peripheral targets in vivo. We present a speculative model based on Poisson statistics, which attempts to account for the variability in the amount of neurite outgrowth from dissociated neurons. © 1995 John Wiley & Sons, Inc.     

Effect of egg storage duration and brooding temperatures on chick growth,intestine morphology and nutrient transporters

The effects of egg storage duration (ESD) and brooding temperature (BT) on BW, intestine development and nutrient transporters of broiler chicks were investigated. A total of 396 chicks obtained from eggs stored at 18°C for 3 days (ESD3-18°C) or at 14°C for 14 days (ESD14-14°C) before incubation were exposed to three BTs. Temperatures were initially set at 32°C, 34°C and 30°C for control (BT-Cont), high (BT-High) and low (BT-Low) BTs, respectively. Brooding temperatures were decreased by 2°C each at days 2, 7, 14 and 21. Body weight was measured at the day of hatch, 2, 7, 14, 21, 28 and 42. Cloacal temperatures of broilers were recorded from 1 to 14 days. Intestinal morphology and gene expression levels of H⁺-dependent peptide transporter (PepT1) and Na-dependent glucose (SGLT1) were evaluated on the day of hatch and 14. Cloacal temperatures of chicks were affected by BTs from days 1 to 8, being the lowest for BT-Low chicks. BT-High resulted in the heaviest BWs at 7 days, especially for ESD14-14°C chicks. This result was consistent with longer villus and larger villus area of ESD14-14°C chicks at BT-High conditions. From 14 days to slaughter age, BT had no effect on broiler weight. ESD3-18°C chicks were heavier than ESD14-14°C chicks up to 28 days. The PepT1 and SGLT1 expression levels were significantly higher in ESD3-18°C chicks than ESD14-14°C on the day of hatch. There was significant egg storage by BT interaction for PepT1 and SGLT1 transporters at day 14. ESD14-14°C chicks had significantly higher expression of PepT1 and SGLT1 at BT-Low than those at BT-Cont. ESD14-14°C chicks upregulated PepT1 gene expression 1.15 and 1.57-fold at BT-High and BT-Low, respectively, compared with BT-Cont, whereas PepT1 expression was downregulated 0.67 and 0.62-fold in ESD3-18°C chicks at BT-High and BT-Low. These results indicated that pre-incubation egg storage conditions and BTs affected intestine morphology and PepT1 and SGLT1 nutrient transporters expression in broiler chicks.     

Reproductive measures and chick provisioning of Cory's Shearwater Calonectris diomedea borealis in the Azores

Capsule Timing of breeding influenced wing-length at fledging, and egg size may be an indicator of fledging weight and the amount of food received by chicks.

Aims To investigate chick growth, temporal patterns of chick food provisioning and the importance of indices of parental condition or quality, egg size and hatching date, to predict nestling body mass and wing-length at fledging, and compare breeding and chick feeding characteristics between colonies in the northeast Atlantic.

Methods A survey of Cory's Shearwater nests was carried out at Vila islet. A sample of 52 chicks, ringed and weighed at hatching, was selected to study chick growth and food provisioning.

Results Hatching success (51%) was much lower than fledging success (87%). Both hatching date and egg size contributed to explain wing-length at fledging, but hatching date, which was negatively correlated with wing-length at fledging, had the most important contribution (22%). There was some indication that egg size may explain variation in fledging weight and the amount of food received by chicks. Food delivery and feeding frequency of chicks varied throughout the chick development stage and three phases were distinguished: (1) 0–29 days, the highest feeding frequency values and a linear increase in food delivery; (2) 30–69 days, an oscillation in food delivery and medium feeding frequencies; (3) 70–90+ days, a sharp decrease in both food delivery and feeding frequency.

Conclusion Variation in food availability did not seem sufficient to override the overall importance of indices of parental quality in determining reproductive measures and chick provisioning. Breeding and feeding characteristics were similar between colonies in the northeast Atlantic, with variability in chick provisioning higher further south.     

A simple tool for calculating egg shape,volume and surface area from digital images

The geometrical properties of eggs – such as volume and surface area – have uses ranging from ecological, physiological and morphological studies in birds, to predictions of chick condition in the poultry industry. Although measurements of an egg's length and breadth can be used to approximate its geometry, the coefficients used in these models are specific to the original test population, and intraspecific variation in egg shape means these methods cannot be used reliably beyond that population. Here I present a novel mathematical formula to describe the curvature of a bird's egg that can be used to calculate the shape, volume and surface area of an egg precisely from digital images. Using data from several species I demonstrate that the model has a greater level of accuracy than length‐ and breadth‐based methods, and release the user‐friendly tool for others to use for measuring eggs from digital images.     

普通鸬鹚鸟卵溶菌酶与巢密度及卵顺序和新城疫病毒母源抗体关系

亲鸟可通过母体作用向鸟卵传递不同的免疫物质,用于免疫防御,对提高子代生存率至关重要。本研究在青海湖鸬鹚岛共采集60枚普通鸬鹚(Palacrocorax carbo)鸟卵,并同时记录巢密度和卵顺序,通过血凝抑制试验和溶解实验分别测定鸟卵溶菌酶浓度和新城疫病毒(Newcastle disease virus,NDV)母源抗体效价。对鸟卵溶菌酶浓度与巢密度进行Pearson相关分析,利用单因素方差(One way ANOVA)分析鸟卵溶菌酶浓度与卵顺序关系,利用t检验分析新城疫病毒阳性鸟卵与阴性鸟卵溶菌酶浓度差异性,对新城疫病毒阳性鸟卵抗体效价与溶菌酶浓度进行Spearman相关分析。(1)不同窝的鸟卵溶菌酶浓度与巢密度呈正相关性(r=0.886,P0.000 1);(2)同一窝内鸟卵溶菌酶浓度随着卵顺序的增加而增加(F=3.95,P0.05),且新城疫病毒阳性鸟卵的溶菌酶量高于阴性鸟卵(t=4.08,df=58,P0.001);(3)在新城疫病毒阳性鸟卵中,其新城疫病毒抗体效价与溶菌酶含量呈负相关关系(r=﹣0.840,P0.001)。上述结果表明,亲鸟会根据繁殖密度和卵顺序来调节向鸟卵分配的溶菌酶,同时会调节向鸟卵中传递抗新城疫病毒母源抗体和溶菌酶浓度,从而使免疫防御作用最大化。