Oleksandr Todorchuk, founder of UAnimals, an animal rights movement, said the Russian troops had stolen animals from a local zoo.
"They have taken most of the zoo's collection to Crimea: from llamas and wolves to donkeys and squirrels," he said on Facebook.
In a major humiliation for the Kremlin, the Russian army withdrew from the city of Kherson on Friday.
Kherson was one of four regions in Ukraine that Russian President Vladimir Putin claimed to have annexed in September.
Ukrainian president Volodymyr Zelensky said on Saturday that before fleeing Kherson, the Russians "destroyed all critical infrastructure -- communication, water supply, heat, electricity."
Ukrainian television broadcasts have returned and officials said on Saturday that authorities were working to de-mine the city, record Russian crimes and restore power supplies.
On Saturday, in the formerly occupied village of Pravdyne, outside Kherson, returning locals embraced their neighbours, with some unable to hold back tears.
"Victory, finally!" said Svitlana Galak, who lost her eldest daughter in the war.
"Thank god we've been liberated and everything will now fall into place," the 43-year-old told AFP.
"We are Ukraine," added her husband, Viktor, 44.
Several disabled anti-tank mines and grenades could be seen in the settlement, which is home to a Polish Roman Catholic church, with a number of damaged buildings also visible.
While de-mining is carried out, a curfew has been put in place and movement in and out of the city has been limited, local authorities said.
The city of Kherson -- which serves as a gateway to the Black Sea -- was the first major urban hub to fall after Russia invaded in February.
Zelensky has said that Ukraine's forces had established control over more than 60 settlements in the Kherson region.
Ukraine's police chief Igor Klymenko said on Saturday that around 200 officers were erecting roadblocks and recording "crimes of the Russian occupiers".
He urged Kherson residents to watch out for possible landmines laid by the Russian troops, saying one policeman had been wounded while de-mining an administrative building.
A woman and two children were taken to hospital with injuries after an explosive device went off near their car in the village of Mylove, police said.
Across the Dnipro River in the east, local pro-Moscow authorities in the district of Kakhovka issued an evacuation order to its employees to head to the Russian region of Krasnodar.
Ukraine's armed forces said late Saturday that Russian forces were "strengthening fortification" of the defensive lines on the left bank of the Dnipro.
Kherson's full recapture opens a gateway for Ukraine to the entire Kherson region, with access to both the Black Sea in the west and the Sea of Azov in the east.
'What was it all for?'
On Saturday, an increasingly isolated Putin spoke by phone with Iranian President Ebrahim Raisi, pledging to intensify political and trade cooperation, the Kremlin said.
Shunned by the West over his offensive in Ukraine, the 70-year-old leader will not travel to Indonesia for the G20 leaders' summit next week.
US secretary of state Antony Blinken hailed the "remarkable courage" of Ukraine's military and people and vowed US support "will continue for as long as it takes" to defeat Russia.
In London, British defence secretary Ben Wallace said Russia's "strategic failure" in Kherson could prompt ordinary Russians to question the war.
"Ordinary people of Russia must surely ask themselves: 'What was it all for?'"
The Kremlin insists that Kherson remains part of Russia.