severe and geographically widespread droughts, such as a year drought in the late s and a year drought in the late s in the friends tv show fast and furious characters shirt American southwest, have recurred once or twice every years deMenocal . Adaptation requires multidisciplinary approaches integrating scientific, technological and social dimensions. For
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through new economic models that help enable access to credit and loans to support policies that balance cash and food crops. Food utilisation involves nutrient composition of food, its preparation, and overall state of health. Food safety and quality affects food utilisation. RAPs are consistent with and complement the RCPSSP approaches for use in agricultural model intercomparisons, improvement, and impact assessments. One contribution of to a Theme Issue ‘Impacts of environmental change on reproduction and development in wildlife’. The average arrival dates of of migrant species breeding in England have advanced about days over friends tv show fast and furious characters shirt the last years The earlier arrival in spring is correlated with rising temperatures on their wintering ground in sub-Saharan Africa. Interestingly, the duration of their stay in England is the same as years ago because they have also shifted their departure time earlier in the fall by an average of days . Seasonal phenology of the annual cycle and its variation associated with latitude has been intensively studied in four subspecies of white-crowned sparrows Z. leucophrys in the western USA. One subspecies is sedentary, one is either migratory or sedentary and two subspecies are migratory . When the first date of egg laying among the four species is examined as a function of the latitude of breeding grounds, egg laying begins in mid-March at .° N, the last week in April at .° N and the last week in May at Gonadal recrudescence is strongly controlled by photoperiod in this species . Sensitivity to changing daylength as a Zeitgeber has not been studied in all of the subspecies. However, the differences in breeding schedules as a function of latitude suggest strongly that different daylengths on the wintering grounds, coupled with variations in circadian rhythms of photosensitivity, are used by each population as the cue with which to begin migratory and breeding preparations. Sensitivity to a particular Zeitgeber varies significantly among species. Species that begin migration early in the spring use a shorter daylength on their wintering grounds as the cue to begin molt and fattening compared with the longer daylengths used by species that begin migration later
Coordination of annual cycles with a very predictable Zeitgeber can also vary within species distributed over broad geographical ranges and even within populations. For instance, variation of several weeks in the first date of egg laying has been noted between upland and marsh populations of song sparrows . The annual cycles of birds appear to be programmed so that breeding takes place at the most propitious time of the year, which is, in most cases, the time of both moderate air temperatures and optimal food supplies . The other phases of the annual cycle are arranged around the breeding schedule so that the birds are physiologically and behaviourally ready to breed at the right place and at the right time . Egg laying in red crossbills, Loxia curvirostra, has been documented in every month of the year throughout their range in North America. This species has a very long period of reproductive competence compared with most species breeding in temperate North America. This ability allows crossbills to adjust to both seasonally predictable and unpredictable food supplies . Some birds live in environments in which food supplies adequate to foster breeding vary unpredictably. Zebra finches breed over approximately per cent of the Australian continent, including in some very arid and semiarid deserts in which rainfall is highly unpredictable. These finches feed almost exclusively on grass seeds throughout the year, but breed only following rainfall of sufficient quantity to cause seed set . Zebra finches can lay eggs within two weeks following rain because the gonads do not regress fully following the previous breeding epidsode. Instead, they remain in a semideveloped state from which rapid follicular growth can occur more quickly than if the ovaries were fully regressed . Precipitation patterns, as judged by tree ring chronologies and lake sediments, have also varied considerably over time Woodhouse & Overpeck . Intense, short and relatively geographically restricted droughts, such as those in the s and s in the USA, have occurred roughly one to two times per century over the last millennium. Extremely
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