The Rare Black Storks of Estonia

Black Storks have gorgeous plumage. Their back, head, wings, and neck are a glossy black breaking into iridescence on their neck and chest. Their belly is white. They have a red bill and red legs. The juveniles are simply a little duller overall. They are large birds weighing on average 3 kg. They range in height from 95-100 cm. They are monogamous during their breeding season. The female lays 3-5 white eggs that hatch between 32-38 days. The storklings will fledge around 71 days but, they remain dependent on their parents for food and protection as well as training for longer. They make their stick nests in coniferous and mixed forests.

Black Storks are very rate in Estonia. It is the northern limits of their range. Most researchers thought it was the Pine Marten eating the eggs in the nests that caused such low numbers but recent research suggests something else. In an article titled, ‘The black storks in Estonia are suffering from loneliness’ by the Estonian Research Council of 6 February 2019, the analysts said:

As a surprise, it came out that one third of the nests of the Black Stork in Estonia are inhabited by single birds who cannot breed due to lack of partner. Such single birds may leave their nests and annoy breeding couples. Thus, the Black Stork in Estonia lack partners who may have died on long migration routes or proceeded to breed elsewhere where living conditions are more favourable than here. 

While not having a partner would significantly impact the breeding of the Black Stork, a more recent article suggests that the Black Stork is in danger of disappearing altogether due to low reproduction rates. Tests on storklings indicated a high concentration of mercury in their system. They believe that the levels in the fish that the storks eat is so significant to cause infertility. Two other issues are parasites and human intrusion (Low birth rates may spell black storks’ disappearance from Estonia’, ERR news, 16 March 2021).

There is a Black Stork nest in Karula National Park in Southern Estonia. The storks are known to have been using this nest since 2016. The current adults are ringed Karl II (715R) and Kaia who joined Karl in 2020.

In the image below, Kaia is waiting for her turn to incubate the eggs. Karl II is just getting off the nest. You can see his ring and number on his left leg.

Karl II is equipped with a backpack GPS transmitter. Kaia does not have one and she is not ringed. The GPS monitor tracks Karl II to his winter migration home in South Sudan and return every year. Here is a map of that route for his return in 2021:

No one knows where Kaia stays during the winter as she does not have a tracker.

In 2021, Kaia laid five eggs from the 24-30 of April. One of the five eggs was broken on 25 March. You can see that broken egg to the right of the nest. Another egg broke on 25 May leaving the couple with three eggs – a much easier number of chicks to keep healthy and strong. In addition, Kaia is a first time mom.

Karl II helps to incubate the eggs as well as nest maintenance and aeration. Here is an image of him aerating the nest. It has been raining a lot. This helps to dry out the straw and moss so there are fewer parasites.

While Kaia incubates the eggs, Karl II keeps himself busy bringing in nesting materials.

The weather in southern Estonia was not good towards the end of May when hatch watch would be starting. There were heavy rains often with hail hitting Kaia or Karl II when they were incubating. When the sun is out and the moss in the forest is dry, Karl II will bring in new moss to line the nest cup where the eggs are.

On 27 May, Kaia can hear ‘the egg talking’ – it is a bit of a quack, a high pitched sound:

The storklings continue to talk to the parents. Karl II continually brings in soft moss and dry materials to make the nest soft and dry as hatching gets closer.

This is Kaia. Her very first chick hatched at 8:51 am on 28 May. She is not ready to show us!

Awww. There it is.

Karl II comes in at 9:44 and both parents look at their lovely little chick together.

Here is a close up

Have you ever seen an adult stork feed a wee storkling not even a day old? Well, here is your chance:

Kaia brings in an adder, a snake, to the nest along with the little fish. The storkling is eating.

At 17:44 there are two storklings! This is super. They are both born on the same day.

Karl is really bringing in lots of food. There are tadpoles, earthworms, tiny fish, viper snakes, and now a second or third eel.

Kaia regurgitates food on the slope for the little ones to eat.

A crack in the third egg appears on 30th May. The little one looks down to see its sibling hatching.

At 18:20 on the 30th of May, the third storkling is out of its shell. Meanwhile, its two older siblings are gobbling up food from the side of the nest.

The trio is with Kaia, their mom, today, 5 June 2021. It is 10:09:21. Looking good!

I hope that there is plenty of food for everyone. It looks like that is the case. If not, Black Storks (as well as white ones) will toss the smallest from the nest if it means there would be three unhealthy chicks instead of two healthy ones. Fingers crossed. This little one is five days younger than the oldest.

You can watch this family in Estonia here:

Thank you for joining me today. I hope you liked reading about the Black Storks. They are so beautiful but, unlike the White Storks in Mlady Buky, they do not like so much to be around people. This streaming cam is a wonderful way to observe their daily lives and challenges.

Take care!

Thank you to the Eagle Club of Estonia and Kotkaklubi for their streaming cam where I grab my screen shots.

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