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Moscow mallards reveal the secret

If you ask the Moscow mallards as they assessed the results of last summer, they would have answered, positively. The number of broods of these ducks in urban rivers and ponds increased by 6% compared to the summer of 2015 and has exceeded 900. 2016 — first year, when the number of the dominant view of Moscow waterfowl in summer and winter is steadily growing.

The total number of Mallard broods in Moscow has grown in 19 years from 250 to 950, and the total number of Chicks in with them 1300 to nearly 4,500. What is the secret? Let’s try to answer this question, summarizing nineteen waterfowl Moscow in June — July this year.

The success of nesting ducks, like other birds, is associated primarily with the characteristics of the weather of the past and current seasons. Modern climate is changing uncontrollably. According to the Hydrometeorological center of Russia last winter was the warmest in the Central Federal district, including in Moscow, trailing only the winter of 2015. At the end of January was warmer, and the weather became almost spring. The frosts have returned, but not for long. Warm winter remained for the whole of February with an anomaly temperature of 7.1 °C compared to mean multiyear. In March the average temperature exceeded the norm by 3-5 °C in April — at 2-4 °C. the Average temperature for may 2016 was 1.9 °C above normal. In General, the weather in spring 2016 (March — may) in the Northern hemisphere was the warmest for this period in the entire 126-year history of regular meteorological observations. Summer was also warmer and more humid than usual.

All this was conducive to successful wintering, and nesting of urban mallards. The main reason for long-term growth in the number of broods was the early beginning of spring. In early spring it nests almost 40% more females than late, they have also slightly increased the size of the masonry. On the other hand, the sooner it gets warmer the longer term needs females to prepare for reproduction. It is well known to hunters from different regions of Russia. So, in the Kuban mallards with the arrival of the long “wait” before putting down the first egg, in Karelia begin laying almost immediately after returning from hibernation. The further North, the shorter the interval. Moscow shows a striking example of this pattern in one geographical point. In late spring ducks breed in the Northern format, and early on the “South”. Although spring in Moscow with climate change comes early, late spring — is not uncommon. For the last 19 years in Moscow there were ten of them, and only nine — earlier. In recent years, in Moscow Mallard ducks start laying eggs at about the same time as in Crimea.

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Determining the age of the Chicks in different broods, and calculating the time of their hatching, ornithologists have discovered that the mass appearance of Chicks in urban rivers and ponds is shifted to the beginning of the season. So in June of 2016 for the ponds out of 44.6%, and in 2015 — 30%. In July, on the contrary, in 2016 — 2.7%, and in 2015 — 8%. Litter size in the city, as in nature, reduced the growth of Chicks: the number of feathered ducklings on a female less than five, and jackets, more than five.

The laying period in Moscow lengthened by the fact that, on the one hand, more females nesting earlier, and with another — most of the females lost their offspring by the frequent destruction of nests and the death of broods, nests later, already in the second half of June. The stretch of the period of masonry in Moscow is on average from 61 to 93 days, while in the nature of from 25 to 75. Ducklings later broods are rising at a declining duration of the day. It inhibits the desire to migrate and promotes the transition to a settled way of life.
Grown over the summer, the population of mallards is very attractive for autumn migrants. On migration it is growing back in several times. Joining the bulls ducks stay with them for the winter, and some — and the next nesting period.

Thus, since the beginning of “oporozhnenie” mallards started in the last century the ice-free wintering in city reservoirs and supplemented by generous handouts of citizens, successfully developed parallel to mitigation of climate. It is expressed in the transition to residency, the lengthening of the egg-laying period, increase the number of breeding females, the appearance of migratory birds during migration. The growth of the urban mallards currently is the principle of positive feedback: the more breeds, the more winters and Vice versa.

With the appearance of spontaneity to this process in it outlines the elements of self-regulation. Together with the increasing number of females statistically significantly reduced the average size of broods hatched later on down jackets, in which ducks and no less than in early. Late ducklings are vulnerable to many troubles, particularly by many older broods. The townspeople feed the birds all year round, and city mallards, accustomed to feeding in the winter, are willing to use it in the summer. The sight of a man with food, they are from all sides rush to the dressing and create a true pandemonium. While the females attack other people’s ducklings and their mothers, mixing and dispersing broods. In such fights, the younger one gets more than anyone else. They lag behind their, lost, weak, become prey for predators, not compete with the older, time can not warm up, not being able to get out of the “improved” reservoir with vertical walls. All this leads to increased waste ducklings younger age categories.

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European ornithologists have conducted experiments, which showed that the transplantation of several ducks with a feather from one pond to another, where there are living broods of mallards, leading to the death of ducklings and reduced the size of broods. Moscow mallards confirm this. The effect of self-regulation by younger age groups do not notice, as a rule, records in the nature, as before hunting for the grown ducks. The lengthening of the period of masonry and, consequently, the emergence of ducklings on the ponds can also be considered a mechanism for reducing competition broods in the struggle for resources. The long period of egg laying and hatching is associated not only with climate but also with the fact that females of different ages and with different backgrounds choose to nest different security and inaccessibility of the place, the care of the broods, which leads to their loss of the less experienced and “creative” females. Thus, we have to start all over again, retreating to the not too favorable end of the season and thereby reducing competition.

Long-term monitoring of waterfowl Moscow helped to reveal the main secrets of well-being of urban mallards in a changing world. The loss of regular flights, they have increased both due to additional forces of nature, and due to the transition to the very early nesting, stretched egg-laying period and the emergence of ducklings facilitated the transition to residency the young of later broods, reduced competition due to the effect of self-regulation. And, of course, if not for the generous “humanitarian aid” Muscovites, everything could have been different.
 

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