Night herons research notes

24 Aug 2020 | News

The LIFE.VISTULA.PL project includes not only protective actions on ponds or the Goczalkowice Lake, but also research on the state of the night heron population.

1. We can follow the feeding habitats of night herons on a map available to ornithologists working within the LIFE.VISTULA.PL project. This is possible due to special transmitters. The results of the observations are very interesting, mostly in line with previous observations carried out for many years on ponds, before the latest research technologies were introduced. Night herons feed most often on the shores of breeding ponds, where they spend a lot of time looking for fish. Interestingly, many statements of foraging birds refer to very small watercourses used alternately with ponds. Sometimes night herons also use unusual places, e.g. concrete thresholds on the storm drain from the Goczalkowice Lake.

2. Although the breeding season of night herons is coming to an end, works within the LIFE.VISTULA.PL project are still ongoing. Counting nests in colonies after birds have left is the most important task in August and September. Counting the nests requires focusing and analyzing each pile of twigs. In the colony, you also have to watch your steps because there are dead young birds under the nests. Unfortunately, it happens that young birds fall out of the nest and die under the bushes. Finding the its remains is also not easy because they mummify quickly and are not easy to spot.

3. Counting night herons nests in colonies requires proper preparation. For over 30 years of monitoring the population of this species in the Upper Vistula Valley, ornithologists have developed standards not only for counting, but also for proper protection of nests. There is no human activity on the islands on the ponds, and nature and birds have its own rights there. This small area of ​​the island, overrun with elderberry, willow, hawthorn and thick blackberry bushes, is a safe place for birds, but not for ornithologists who control them several times a year. Squeezing through a thicket of dry branches and exuberant shoots of thorny blackberry may hurt and cause more serious injuries. Safety glasses and a hat are essential. On the island you have to move slowly so as not to disturb its shores, which are blurred by the waves. As part of the LIFE.VISTULA.PL project, the shores of the islands will be strengthened and some of the islands will be cleared of excess dry branches to facilitate research and checking the effects of conservation measures in the coming year

4. During the incubation of eggs and raising the young in the colony, ornithologists monitored the behavior of adult night herons in the nests. Due to used camera traps, it was possible to record what night herds were doing in the nest during the day and at night. The collected footage, hundreds of hours long, will be analyzed in detail and will undoubtedly contribute to the acquisition of knowledge for the further protection of night herons in the Upper Vistula Valley.

5. In 2020, it was the second season of scientific work within the LIFE.VISTULA.PL project, consisting in marking adults and young night herons with rings and transmitters enabling the location of birds. In this way, we want to know the feeding sites of night herons during the breeding season and after leaving the breeding colonies.
In August, night herons are already scattering and we can see that most of them remaining in the region of the Upper Vistula Valley, but sometimes they also move much further, even north of the breeding grounds. In July, one of the birds flew as far as Poznań.

6. During the control of night heron colonies, ornithologists, in addition to the basic research included in the LIFE.VISTULA.PL project, also conduct additional observations and document them with photos.
Observations of night herds in nests and in colonies are aimed at determining how often birds in the second year of life breed. Usually, birds decide to make their own nest for the first time only when they are three or four years old, when they have the full plumage of an adult bird. Not fully mature birds are more and more often seen in colonies and start to nest, which may be the reason for the success of the population of night herons in the Upper Vistula Valley.

7. Moreover, during multiple inspections of ponds ornithologists observe also other bird species. Data from such observations are recorded in the system, most often through the NaturaList application. It’s possible also to add photos of birds.  This was also the case at the ponds in Ochaby, where in the spring of 2020 it was possible to see and photograph the most effective and at the same time the rarest regularly breeding duck in Poland – the red-crested pochard. A pair of birds with two cubs swam on a pond where night herons also nest. The male pochard in the mating robe make a stunning impression not only on the female duck, but also on every person sensitive to the beauty of nature.

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