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The effects of climate change on birds

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Birds, like all living beings, are subject to the action of the climate, which is  expressed by weather conditions and
their intra and interannual variations; their morphology, their physiology, their behavior, the phenology of their main activities (reproduction,migration, search for areas wintering ...), the selection of
their seasonal habitats are all answers to these climate characteristics.

These morphological and physiological characters, like their "traits of life history "are the result of the pressure of selection exercised environmental conditions, of which climate is one of the main components

A climate change therefore amounts to a change in the selection pressure, and it is therefore legitimate to wonder, if one is interested in the conservation of the birds, on the consequences of this modification.A climate change therefore amounts to a change in the selection pressure, and it is therefore legitimate to
wonder, if one is interested in the conservation of the birds, on the consequences of this modification.

Is there an impact of climate change on phenology in birds?

there is already evidence in birds of phenological changes in migration and nesting dates, but the consequences of which are poorly understood. Depending on the species, we can observe appropriate responses or not, including no response and phenological disjunction (the animal is no longer synchronous with its environment).there are extrinsic and intrinsic factors that could inhibit adaptations to climate change.Both researchers Sparks and Mason confirm that he there is a lot of data on the dates changes arrival of migratory birds at spring, but little on the dates of departure in winter; he analyses
the first arrivals and the last departures of the winter visitors of certain species, with results often contradictory, not allowing to conclude.

About reproduction, climate change underway lead to an advance of spring cycle phenology reproduction; There is no reason, at first sight, to think that the components of the food chain will vary at the same rate. This differential slip could therefore lead several species to lay at the wrong time (phenomenon of asynchrony). The consequences for species will be all the more serious as the evolutionary selection, which will lead to changing the start date of the
reproduction in a more timely manner, will be carried out with a extended latency.

What effects can we expect on birds whose phenology is under the influence of photoperiod?

In birds, the photoperiod is the most important factor in synchronizing reproduction, moulting, migration, with recurring seasonal fluctuations environmental conditions.

Man-made environmental changes can affect birds responding to photoperiod in two ways:

1-  the photoperiod can become a bad
predictor of favorable conditions, if the synchronous relationship between resources dependent on the temperature and length of the day change;

2- certain species may be forced to change their distribution, to remain at latitudes where the climate is favorable to them, with, as a first consequence, difficulties for these species to find new favorable habitats; in addition, they will expose themselves to new conditions of photoperiod. In both cases, it is expected that the birds will respond in an adaptive way, and that the response photoperiodic itself be the target of the selection. Thus, some species will be able to adapt to these changes but to the only provided that the genetic selection of birds adapted to the new conditions occurs quickly enough.



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