1. Mallard (Anas platyrhynchos L
Mallard (Anas platyrhynchos L.) as an urban species: twelve years of summer waterfowl census in Moscow
For about forty years Mallard has been a common urban bird of Moscow. Using monitoring techniques, we estimated the total abundance, brood size, nest-initiating and hatching dates of urban Mallards. Data obtained over the last twelve seasons allowed us to test whether the dense distribution over urban water bodies and air temperatures affect the brood size and the duration of the nesting period of ducks.
Ksenia V. Avilova. Dept of Biology, Moscow State Lomonosov University, Moscow, Russia
A Guide For Aging Duck Broods In The Field (Gollop, Marshall, 1954; Isakov, 1963)
Broods appear at the urban water bodies during the whole summer. Compensatory clutches are common to the species in case the first clutches or broods have been predated. The egg-laying period in Mallards lasts for days in Moscow.
RESULTS. Mallard is the most numerous waterfowl species of Moscow. In 1998–2004, the abundance of mallard broods fluctuated between 250 and 540; since 2005 it has been increasing rapidly and by 2009 reached 900 broods (N=12, rs = 0,90, р < 0,001).
Methods. Number dynamics and reproductive success of the urban population of Mallard in Moscow were estimated for the period of Ducks were counted in each July at the fixed routs running along urban ponds and rivers. Age of ducklings was determined in accordance with the scale developed by Marchall and Gallop (1954) in Isakov’s modification (1963). The dates of the nest initiation and hatching were calculated on the basis of the age of the observed ducklings
The high population density of ducks at urban water bodies comes into conflict with the habitats capacity. There are three ways to mitigate these contradictions.
1. Prolongation of the nesting period.
2. Earlier nest initiation
3. The reduction of the brood size.
The abundance of Mallard broods has been increasing rapidly since 2005 and reached 900 broods in 2009
1 – 6 days
7 – 12 days
13 – 18 days
26-35 days
19 – 25 days
36 – 45 days
46 – 55 days
Primary sites of localization of the Mallard broods in Moscow
ducklings
females
Broods and ducklings number in
The nest initiation date negatively correlates with the number of breeding females: the more females initiate nesting the earlier they start laying. Over the study period, the nest initiation has shifted to the earlier dates.
The number of broods correlates with the length of the nesting period in when population grew.
The number of ducklings per female has decreased over the 12-year period along with the growth in the number of females. It is the essential mechanism of number auto regulation in the dense urban population.
Year
Date of the
temperature
rising
Date of the 1-st egg laying
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Intervals between the 1-st of March, the rising of mean air temperature and the date of the 1-st egg laying
The date of laying of the 1st egg depended on the raising of the mean daily air temperature above the freezing point only during the period of fluctuations of the duck number ( ). Later, in the period of the population increase ( ), these relationships were not significant.
Table 1. Dates of the mean air temperature raising above zero and of the laying of the first egg in Mallards
Photo: M.Ricci
The reproductive success and the timing of reproduction in urban Mallards depend mostly on the population density and, to some extent, on the weather conditions.
Photo: I.Kuzikov