The north of Algeria is the site of important wetlands and lagoons of high ecological, cultural and economic features, with significant capital to preserve. The country ratified the Ramsar Convention in 1982, including 50 wetlands, occupying more than 2.99 million hectares, or 50% of the estimated total area of wetlands in Algeria, of which 762 are natural and 689 are artificial. Migratory birds are a most important feature and henc the focus on the study of a model that is the white stork Ciconia ciconia. To explain the link between this species and the wetland, we made a survey of the distribution of nest, using a GPS, from 1996 to 2014. The impact of environmental changes affects the dynamics of the white stork living near the coastal zone in northeastern Algeria. There are several parameters governing the abundance and reproduction of storks which are marked by an average fertility compensated by a high proportion of breeding pairs or by changing the behavior migratory of certain sedentary groups.

The white stork Ciconia ciconia in the northeast of Algeria, and its relation with climatic change between 1996 and 2014

. The timing of breeding and nest location in colonial birds may have fitness consequences. In particular, it has been demonstrated that peripheral breeders perform less well than core breeders. To determine whether environmental factors such as date of breeding and nest position influence reproductive success, we studied the breeding ecology of a large colony of White Stork Ciconia ciconia at Drean, northeast Algeria, during 2011 and 2012. Mean egg-laying dates varied significantly between years and differed between core and peripheral nests with more precocious laying occurring in the center. Egg-laying in larger nests started earlier than in smaller ones in the core area but neither nest size nor nest position along the core-periphery gradient had any influence on studied breeding parameters i.e. clutch size, hatching success and chick productivity. There was no yearly difference in clutch size which averaged 4.7 ± 0.7 eggs (N = 156 clutches). Mean chick productivity was higher in 2012 (2.85 ± ...

https://bioone.org/journals/acta-ornithologica/volume-50/issue-2/00016454AO2015.50.2.003/Does-Core-Periphery-Gradient-Determine-Breeding-Performance-in-a-Breeding/10.3161/00016454AO2015.50.2.003.pdf

Does Core-Periphery Gradient Determine Breeding Performance in a Breeding Colony of White Storks Ciconia ciconia?

Altricial nestlings in structured families show a diverse array of behavioural mechanisms to compete for food, ranging from signalling scrambles to aggressive interference. Rates of filial infanticide are moderately high in white storks. It has been hypothesized that this unusual behaviour is an adaptive parental response to the absence of efficient mechanisms of brood reduction (aggression or direct physical interference) by nestlings. To test this latter assumption, we analyzed video recordings of 41 complete feeding episodes at 32 broods during the first half of the nestling period, when nestlings complete 90% of growth and chick mortality and size asymmetries are highest. Parents delivered food to all nestlings simultaneously by regurgitating on the nest floor. No direct (bill to bill) feeding was recorded. Senior nestlings were never observed to limit their junior nestlings from eating food, either by aggression or physical interference. Experimental feeding tests revealed that heavier nestlings handled prey items more efficiently and ate food at a higher speed. The high degree of tolerance shown by senior nestlings is unusual among birds with similar ecological and phylogenetic affinities, such as herons. Tolerance by seniors cannot be easily explained by absence of parental favouritism or proximate factors known to affect the occurrence of sibling aggression in other species (rate of food transfer, brood size, hatching asynchrony or length of nestling period).

/pdf/kind-to-kin-weak-interference-competition-among-white-stork-1pr1miwt56.pdf

Kind to kin: weak interference competition among white stork Ciconia ciconia broodmates

One enduring priority for ecologists has been to understand the cause(s) of variation in reproductive effort among species and localities. Avian clutch size generally increases with increasing latitude, both within and across species, but the mechanism(s) driving that pattern continue to generate hypotheses and debate. In 1961, a Ph.D. student at Oxford University, N. Philip Ashmole, proposed the influential hypothesis that clutch size varies in direct proportion to the seasonality of resources available to a population. Ashmole's hypothesis has been widely cited and discussed in the ecological literature. However, misinterpretation and confusion has been common regarding the mechanism that underlies Ashmole's hypothesis and the testable predictions it generates. We review the development of well-known hypotheses to explain clutch size variation with an emphasis on Ashmole's hypothesis. We then discuss and clarify sources of confusion about Ashmole's hypothesis in the literature, summarise existing evidence in support and refutation of the hypothesis, and suggest some under-utilised and novel approaches to test Ashmole's hypothesis and gain an improved understanding of the mechanisms responsible for variation in avian clutch size and fecundity, and life-history evolution in general.

Ashmole's hypothesis and the latitudinal gradient in clutch size

Factores que afectan a la produccion de volantones en el carbonero comun, Parus major , a largo plazo La produccion de volantones ha sido frecuentemente utilizada para estimar el exito reproductor de las aves y esta condicionada por factores que afectan al desarrollo de los pollos, a la supervivencia o a ambos durante su estancia en el nido. Nuestro objetivo en este trabajo fue determinar los factores predictores que influyen en la produccion de volantones a partir de un conjunto de parametros reproductivos basicos y temperaturas locales recopilados durante 25 anos en una poblacion mediterranea de carbonero comun, Parus major , haciendo uso de criterios de informacion para la seleccion de modelos. De las variables estudiadas, el numero de huevos eclosionados por nido resulto ser el factor predictor con mayor influencia en la produccion de volantones, de tal forma que las puestas mas grandes originaron mas volantones, si bien el peso de los pollos antes de abandonar el nido podria haberse visto comprometido. Este resultado sugiere que hay un buen ajuste general entre el tamano de puesta y la disponibilidad de recursos en la poblacion estudiada.

/pdf/factors-affecting-fledgling-output-of-great-tits-parus-major-be4obs6pij.pdf

Factors affecting fledgling output of great tits, "Parus major", in the long term

Survival and reproduction of young can be affected by growth parameters. It is thus important to estimate intraspecific growth rate variability and environmental factors affecting growth to better understand the dynamics of populations and the potential impacts of environmental changes. Growth parameters of White Stork (Ciconia ciconia) nestlings were estimated in eastern Algeria, in the southern part of the species’ range. A total of 2,756 measurements of 65 nestlings from 18 nests were taken for body mass, and tarsus, wing and bill lengths. Individual growth data were used to investigate the effects of nest occupation date, laying and hatching dates, clutch size, number of hatchlings, productivity, hatching order, and brood reduction on nestling growth patterns. Body mass and bill length growth rates were lower in the studied population than in a more northerly White Stork population. This supports the hypothesis of a geographic variation in intraspecific growth parameters. Chicks from nests occupied early reached higher asymptotic body mass but tended to grow more slowly. However, chicks from late arriving birds compensated for the difference in body mass and wing length by higher growth rates. Wing length was significantly affected by asynchrony and hatching order. Last hatched chicks had larger asymptotic wing lengths, lower wing growth rates and longer growth periods. Wings of nestlings from highly asynchronous broods grew faster but took more time to attain the inflection point. Brood reduction had a negative effect on nestling bill length at hatching. Chicks from nests with little brood reduction had a longer bill at hatching than nestlings from nests with high brood reduction.

Fayçal Taleb

Papers

Factors affecting growth parameters of White Stork nestlings in eastern Algeria