Begging at high level simultaneously impairs growth and immune response in southern shrike (Lanius meridionalis) nestlings

Theoretical models suggest that begging should be costly in order to be evolutionarily stable. However, evidence for such a cost is contradictory (e.g. for growth costs) or scant (e.g. for immunological costs). Here, we experimentally test the existence of both costs in southern shrike (Lanius meridionalis) nestlings. Nestlings were paired by nest of origin and similar body mass. In each pair, a nestling was forced to beg for about 30 s h(-1) , whereas the other begged for only 2 s, both nestlings receiving the same quantity of food. At the same time, the nestling response to an antigen (phytohaemagglutinin) was measured. Nestlings forced to beg for longer showed a reduction in growth rate and in immunocompetence when compared to control chicks. The two costs occurred independently of each other and were negatively correlated to time begging. These results strongly support models of honest signalling as well as scramble competition, which predict that begging should be costly in order to be evolutionarily stable.     

虎纹伯劳的巢生境选择与繁殖行为

2005年3~7月通过焦点动物取样法(focal animal sampling)和完全记录法(all-occur rencerecording)对四川南充地区虎纹伯劳的繁殖行为进行了研究。结果表明,虎纹伯劳喜在5~12m的高大阔叶乔木的冠部分叉处营巢。对15个巢址主成分分析表明,前5个主成分特征值均大于1,累积贡献率高达83.15%,说明前5个主成分已经基本包含了所有参数的总信息量。4月下旬开始陆续有虎纹伯劳迁到,初到时并未配对。5月上旬开始出现求偶行为,并伴有递食行为。5月中旬首次见到营巢,两性参与营巢,营巢期5~7d。营巢结束一两天后开始产卵,一天一枚,窝卵数4~6枚。营巢期和产卵期都有求偶和交配行为。产完最后1枚卵后即开始由雌鸟单独孵卵,孵卵期13~14d。两性育雏,育雏期13~15d。     

Impact of Nesting Mortality on Avian Breeding Phenology: A Case Study on the Red-Backed Shrike (Lanius collurio)

The seasonal timing of avian reproduction is supposed primarily to coincide with favourable feeding conditions. Long-term changes in avian breeding phenology are thus mostly scrutinized in relation to climatic factors and matching of the food supplies, while the role of nesting mortality is largely unexplored. Here we show that higher seasonal mean daily mortality rate leads to a shift in the distribution of breeding times of the successful nests to later dates in an an open-nesting passerine bird, the red-backed shrike Lanius collurio. The effect appeared to be strong enough to enhance or counteract the influence of climatic factors and breeding density on the inter-annual variation in mean hatching dates. Moreover, the seasonal distribution of reproductive output was shifted to larger, or smaller, broods early in the season when the nesting mortality increased, or decreased, respectively, during the season. We suggest that population level changes in timing of breeding caused by a general advancement of spring and of the food supplies might be altered by the seasonality in nesting mortality. Hence, we argue that consideration of nesting mortality is of major importance for understanding long-term trends in avian phenology, particularly in species capable of renesting.     

Temporal changes and sexual differences of impaling behavior in Southern Grey Shrike (Lanius meridionalis)

The Southern Grey Shrike (Lanius meridionalis) is a common resident along the rift valley. During 2007-2008 we studied the impaling behavior of Southern Grey Shrikes at the Shezaf nature reserve by food supplementation. Our findings indicate seasonal shifts in impaling behavior. During the winter, there was no difference between the sexes and shrikes impaled house mice (Mus musculus) close to their territorial boundaries with neighboring conspecifics. All impaled mice disappeared from the tree within a few hours of impalement. During the mating season, males impaled the whole prey and let females eat it, and prey was impaled by both sexes only in order to dismember and feed the nestlings. Shrikes impaled and cached meal worms only after they were satiated. The number of meal worms taken to be hoarded increased during the non-breeding season, but during the breeding season male shrikes preferred to feed the females. During the entire research period we did not find any specific cache sites or trees and no prey remained impaled for extended periods of time. In conclusion, impaling prey changed temporally and between sexes: from being a signal for conspecifics to pair bonding.     

Costs and Benefits of Mating in the Grasshopper Chorthippus parallelus (Caelifera: Acrididae)

Fitness consequences of different levels of mating benefits, viz., (1) virgin, (2) seldom mated, (3) free mating chances with the same male throughout the female's life span, and (4) free mating chances with three males always offered, were investigated in female meadow grasshoppers Chorthippus parallelus. No differences among the treatments were apparent in egg number per pod, total egg number per female, and hatching success of larvae. Seldom-mated females had offspring with the heaviest average larval dry weight. We did not find costs of mating in terms of reduced female longevity and residual dry weight between the treatments.     

Evidence from DNA nucleotide sequences and ISSR profiles indicates paraphyly in subspecies of the Southern Grey Shrike (Lanius meridionalis)

We obtained DNA sequence data from mitochondrial (cytochrome b) and nuclear genes (myoglobin and ornithine decarboxylase) to reconstruct the phylogenetic relationships among eight species of shrikes (Lanius). Phylogenetic analyses based on maximum parsimony, maximum likelihood and Bayesian inference all converged into a congruent topology and defined several well-supported clades. Our multi-gene approach based on nucleotide sequences from fast-evolving and conserved genes strongly supported the paraphyly of Southern Grey Shrikes (Lanius meridionalis). The Canary Islands subspecies (L. m. koenigi) differed significantly from its European counterpart (L. m. meridionalis). Furthermore, the genetic distinctiveness of L. m. koenigi was confirmed by ISSR genomic fingerprinting. By contrast, we did not find evidence to distinguish the Canarian Southern Grey Shrike from L. m. algeriensis on the African mainland (Tunisia), and therefore these two taxa may be considered as synonymous. Together, they correspond to a separate species. The origin of the taxa investigated in this study might have originated about 6 Mya at the Miocene/Pliocene boundary when a remarkable worldwide faunal turnover and global vegetation change occurred. The Lanius genus represents a complex and taxonomically challenging group that requires additional research.     

Trophic ecology of the Southern Grey Shrike (Lanius meridionalis) in insular environments: the influence of altitude and seasonality

The seasonal diet and prey selection of the Southern Grey Shrike (Lanius meridionalis) was studied in two different insular habitats: shrub environments of the Canary Islands in coastal and high mountain zones. We measured, in each season, food availability and prey size in order to determine prey size selection of shrikes along an altitudinal gradient. Moreover, we compared the diet patterns observed with those documented on the continent, to determine if Southern Grey Shrikes in the islands’ high mountain zone (which has a continental climate) showed seasonal diet variation similar to those in northern continental areas. We analysed a total of 1,139 shrike pellets collected in 1 year and identified 10,179 prey items. Numerically arthropods (91%), and in terms of biomass lizards (70%) were the main prey consumed by the shrikes. The proportions of the main prey items differed significantly between seasons and habitats. Diet in the coastal areas was less variable than in the high mountain zone. The greater seasonal climatic variation in the high mountain zone was associated with diet patterns similar to those found in some northern continental areas, such as the Iberian Peninsula and southern France. Finally, shrikes selected the largest prey in the high mountain habitat. This suggests that foraging behaviour in this species is related to climatic conditions, as the biggest and most profitable prey were consumed in the most harsh habitats.     

Pattern of energy allocation in the southern catfish (Silurus meridionalis)

Energy budgets were compiled for the southern catfish ( Silurus meridionalis ) under laboratory conditions at different ration size, body weights and temperatures. Though the food energy allocated among the components of the energy budget varied with changing conditions, for the fish fed maximum rations the pattern of energy allocation was independent of body weight and temperature. At the maximum ration about 60% of assimilated energy was deposited in growth and 40% spent in metabolism, indicating a higher proportion allocated to growth and a lower proportion to metabolism than is generally found in fish. This pattern of energy allocation is an energetic strategy adapted to the piscivorous lifestyle of this species.     

Handling Stress as a Measurement of Personality in Great Tit Nestlings (Parus major)

Interest in personality is growing in a wide range of disciplines, but only in a few systems it is possible to assess the survival value of personality. Field studies looking at the relationship between personality and survival value early in life are greatly hampered by the fact that personality can at present only be assessed after individuals become independent from their parents. In passerines, for example, this is often after a period of intensive selection for the survival on fledglings. The main aim of this study is therefore to develop a method to measure personality before this period of selection. For this purpose, we developed the handling stress (HS) test. We measured HS in 14-d-old great tit nestlings by counting the number of breast movements (breath rate) in four subsequent 15-s bouts for 1 min; before and after they were socially isolated from their siblings for 15 min. To calculate the repeatability of HS, we repeated the test 6 mo later. To assess the relationship between HS and exploratory behaviour, we correlated the outcome of both tests. We ran tests both on birds of lines selected for extreme personality and on wild birds from a natural population. We found that birds selected for fast exploration reacted more to HS compared with birds selected for slow exploration and that HS was repeatable in different life phases. We confirmed this by finding an increase in the HS with increasing exploratory scores in wild birds. These results show that we can use the HS test as a measurement of personality, making it a potential tool for studying the relationship between personality and survival value early in life.     

Adoption Behaviour in Little and Common Terns (Aves; Sternidae): Chick Benefits and Parents' Fitness Costs

Adoption seeking by semi-precocial chicks of some bird species can be adaptive since it provides an alternative tactic to permit poorly cared-for young to survive despite their neglectful parents' behaviour. Moreover, own-nest desertion may enhance inclusive fitness of fugitive chicks by increasing survival prospects of siblings. On the other hand, adoption by breeding adults can be detrimental to foster parents' fitness if they invest resources in promoting survival of others' offspring at the expense of their own. In this study we report on the proximate causes and survival consequences of adoption seeking by chicks, and on the presumed costs of adoption sustained by foster parents in two colonial, ground-nesting tern species: the little tern (Sterna albifrons) and the common tern (Sterna hirundo). Adoptions were frequent in little tern and, notably, in common tern colonies. Chicks that deserted their original brood were poorly fed compared with resident chicks, but crowding in the brood and age rank relative to nest companions did not influence the chances of desertion. Deserting their original brood was risky for little tern chicks since stray chicks experienced higher mortality than resident ones. Common tern chicks deserted their original nest significantly more often than little tern chicks. Adoptees of both species benefited by the same survival prospects as resident chicks. A negative correlation existed between the proportion of food given to strange chicks and seasonal fitness or chick survival rate of breeding pairs. This was not predictable because: (1) foster parents could have increased their parental efforts, thus ensuring the same survival prospects to their own chicks, and (2) chicks of foster parents could have been, in turn, adopted thus obliterating the negative fitness effects of adoption. The sexes were identical with respect to their proneness to provide food to strange chicks. We suggest that adoption seeking by little and common tern chicks has evolved as an alternative tactic that is pursued to counter the effects of poor parental care. Adoption behaviour seems maladaptive since it is accompanied by a reduction in seasonal fitness in both species. Possible alternative explanations for nest desertion and adoption behaviour are also discussed.     

Physiological and morphological responses to the first bout of refeeding in southern catfish (Silurus meridionalis)

Many animals experience fasting because of the high temporal and spatial sporadicity of food availability. Once food is available, animals use external energy to restore their depressed functional performance. In the present study, the physiological and morphological responses to the first bout of refeeding in juvenile southern catfish (Silurus meridionalis) were characterized. Fish that had undergone long-term fasting (fasted for 32 days, the S32 group) exhibited a lower resting metabolic rate ( $ {\dot{\text{M}}} $ O_2rest decreased by 49 %), lower peak metabolic rate ( $ {\dot{\text{M}}} $ O_2peak decreased by 24 %), greater energy expenditure (increased by 15 %) during specific dynamic action (SDA) and longer duration SDA response (increased by 41 %) than those of a control group (S0 group, fasted for 0 days). The S32 group showed a significantly reduced peak gastric evacuation rate (0.131 g meal h^?1) compared with the S0 group (0.315 g meal h^?1). The S0 group also had a shorter gastric evacuation time (36 h) than either of the two fasting groups (both 64 h). The S32 group displayed a higher minimum gastric pH (3.1) than the S0 and S16 groups (2.6). Refeeding did not trigger an increase in the wet mass of the gastrointestinal tract, whereas the liver wet mass of the S0 and the two fasting groups increased significantly with refeeding. The trypsin and lipase of the S0 group showed higher mass-specific activities and organ capacities than either of the two fasting groups at certain specific time points. A similar result was found for aminopeptidase activity. Multiple loach meals equaling 6 % of the body weight of the fed fish completely restored the liver morphology within the S16 but not the S32 group. Our results suggest that the regulation of the digestive performance of the gastrointestinal tract in S. meridionalis that are finishing their first small meal after fasting is delayed compared with that of nonfasting fish and that it is similar to the characteristics (lower $ {\dot{\text{M}}} $ O_2peak, greater SDA and a longer duration of the SDA response) of the refeeding SDA.     

Conservation genetics of the loggerhead shrike (Lanius ludovicianus) in central and eastern North America

This study examines geneticstructure of central and eastern North American Loggerhead Shrike (Lanius ludovicianus)populations. Samples derived from 27populations (n = 206) covering the range of threerecognized subspecies: L. l. migrans,L. l. ludovicianus, and L. l.excubitorides, and included locales from aputative intergrade zone between twosubspecies. For L. l. migrans, samplesinclude both those from extant populations andfrom museum specimens spanning approximately130 years. For all samples we obtained 267 basepairs of mitochondrial control region sequenceand identified a total of 23 distincthaplotypes. For a subset of samplesrepresenting a locale centered on the Canadianportion of an intergrade zone between migrans and excubitorides and locales onalternate sides of the intergrade, we obtainedadditional sequence for an intron of thenuclear glyceraldehyde-3-phosphatedehydrogenase gene. Analyses of temporal trendsin control region diversity of L. l.migrans populations indicate a diminutioncoincident with the decline in populationnumbers. Results from an Analysis of MolecularVariance on the control region data showed thata significant amount of total control regionspatial variation was apportioned among thethree subspecies (24.42%; P < 0.01). Furtheranalyses indicated statistically significantdifferences between eastern and westernpopulations of L. l. migrans. We found nosignificant differences among consideredpopulations in frequencies of six identifiedGpdh alleles, although this result ispreliminary because of small sample sizes.However, both the mitochondrial and intron datasuggest a higher genetic diversity in theintergrade zone. Based on our analyses wedefine four management units for eastern andcentral populations of Loggerhead Shrikes.     

Effect of meal size on postprandial metabolic response in southern catfish (Silurus meridionalis)

Effect of relative meal size (0.6-24%) on specific dynamic action (SDA) was assessed in southern catfish juveniles (48.2+/-3.2 g) at 27.5 degrees C. Cutlets of freshly killed loach species were used as test diet. Energy expended during SDA was linearly correlated with relative meal size (r=0.949, p<0.001, N=47). There was no significant difference in SDA coefficient (energy expended on SDA quantified as a percentage of the energy content of the meal) among different relative meal size groups. Factorial metabolic scope increased from 1.47 to 4.08 when the relative meal size increased from 0.6% to 24%. The peak V O2 increased with meal size, but levelled when relative meal size gradually increased to the maximum. SDA duration showed a S-type (slow-fast-slow) increase course with increased meal size. The results of this study suggest that the high postprandial factorial metabolic scope and a trapezoid SDA curve might be the adaptation strategy of warm water sit-and-wait fish under the natural selection of evolution related to long-term food resources.     

Chick Begging Calls Reflect Degree of Hunger in Three Auk Species (Charadriiformes: Alcidae)

Begging behaviour is an important element in the parent-offspring conflict; it has been studied in many avian species. However, the majority of the studies have been entirely based on the call counts, and they agreed that vocal activity was a good indicator of chick’s nutritional need and/or condition. Fewer researches were dedicated to the temporal-frequency variables of the begging calls themselves and they showed contrary results. Here begging behaviour in three burrow nested, uniparous species of auks (Alcidae) was studied. These objects provide an opportunity to study the signalling value of begging calls in the absence of important confounding factors such as nestling competition and predation pressure. I recorded calls of individual chicks in two conditions: during natural feeding and after experimental four-hour food deprivation. I found that almost all measured acoustic variables contain information about the chick’s state in all studied species. The hungry chicks produced calls higher in fundamental frequency and power variables and at higher calling rate compared to naturally feeding chicks. The effect of food deprivation on most acoustic variables exceeded both the effects of individuality and species. In all studied species, the frequency variables were stronger affected by hunger than the calling rate and call durations. I suppose that such strong change of acoustic variables after food deprivation can be explained by absence of vocal individual identification in these birds. As parents do not need to check individuality of the chick in the burrow, which they find visually during the day time, the chicks could use all of the acoustic variables to communicate about their nutritional needs.     

Chromosome location of the ribosomal RNA genes in Triturus vulgaris meridionalis (Amphibia,Urodela)

Ribosomal genes have been localized on mitotic and lampbrush chromosomes of 20 specimens of Triturus vulgaris meridionalis by in situ hybridization with ³H 18S+28S rRNA. The results may be summarized as follows: 1) each individual shows positive in situ hybridization at the nucleolus organizing region (NOR) on chromosome XI; 2) in addition, many specimens exhibit a positive reaction in chromosomal sites other than the NOR (additional ribosomal sites); 3) the chromosomal distribution of the additional sites appears to be identical in different tissues from the same specimen and to follow a specific individual pattern; 4) the additional ribosomal sites are preferentially found at the telomeric, centromeric or C-band regions of the chromosomes involved.Abbreviations rRNA ribosomal RNA - NOR nucleolus organizer region - rDNA the DNA sequences coding for 18S+28S rRNA plus the intervening spacer sequences - SSC 0.15 M sodium chloride, 0.015 sodium citrate, pH 7     

Chromosomal location of the ribosomal RNA genes in Triturus vulgaris meridionalis (Amphibia,Urodela)

The 5S ribosomal RNA genes have been localized in mitotic and lampbrush chromosomes of Triturus vulgaris meridionalis by in situ hybridization. These genes are clustered in a single locus in an intercalary position of the long arm of chromosome XI. In lampbrush chromosome XI the 5S genes are located near a loop landmark mapped at 66 units.     

Chromosome location of the ribosomal RNA genes in Triturus vulgaris meridionalis (Amphibia,Urodela)

The mitotic chromosomes of six specimens from Triturus vulgaris meridionalis have been examined by both in situ hybridization with ³H 18S+28S rRNA and AS-SAT staining method. The results of these two sets of experiments can be summarized as follows: 1) in each specimen the NORs and the additional ribosomal sites, which react positively to in situ hybridization with ³H 18S + 28S rRNA, are also stained by silver; 2) other chromosomal regions, which do not hybridize in situ with ³H 18S+28S rRNA, are on the other hand stained by the AS-SAT method. These latter Ag-positive sites show a species-specific pattern of chromosomal distribution.     

Extra heterochromatin in natural populations of Gomphocerus sibiricus (Orthoptera: Acrididae)

Two types of extra heterochromatin, in the form of either supernumerary segments or B-chromosomes, have been observed in natural populations of Gomphocerus sibiricus. The presence of a heterochromatic supernumerary segment affecting the M₇ pair in a population from the Valle de Arán disturbs the normal separation of this bivalent at anaphase I of meiosis and non-disjunction products, respectively deficient or duplicate for the M₇, are present at metaphase II.A stable B_m chromosome has been detected in a second population from Formigal. In a single individual where a B_m is present together with a small unstable B_s supernumerary chromosome both the B_m and the M₅ are unstable in the germ line and in the case of the M₅ this unstability leads to a state of germ line polysomy.