They were among five positive events reported in South Australia on Monday.
The pelican was found to have been infected with bird flu after being discovered at Edithburgh on SA's Yorke Peninsula.
But authorities have not confirmed whether it died from the virus.
The sea lion, found dead at Victor Harbour, was sent for testing.
It comes after the first Australian sea lion was confirmed to have died from the virus on Sunday.
There are fears for the survival of Australian sea lions due to the small overall size of the population, thought to number fewer than 12,000.
The endangered sea lions are the rarest species of seal in Australia, with more than 80 per cent of its total population found in SA.
About 100 birds are due to receive a second dose under a SA vaccination program for captive birds at Cleland Wildlife Park, Adelaide Zoo and Monarto Safari Park.
But no suitable immunisation was available for threatened mammals such as sea lions, SA Environment Minister Emily Bourke said.
"There is no off-the-shelf vaccine available, no vaccine that has been approved at a national level," Ms Bourke told reporters on Monday.
Pelicans are also considered at very high risk from the virus due to their gregarious nature, wide distribution and colonial nesting habits.
Tens of thousands of pelicans are breeding at Kati Thanda-Lake Eyre, in a rare event prompted by massive summer rainfall.
If infected birds were to travel to the colony, experts fear there could be devastating losses.
Australian pelicans are distributed around the coast as well as inland, including throughout the Murray-Darling Basin, the country's largest river system.
Pelican populations worldwide have been hard hit by HN51, with an estimated 40 per cent of Peruvian pelicans already wiped out by the virus.
The five positive events reported on Monday also included silver gulls at Port Noarlunga South, little penguins on the Limestone Coast's Nene Valley and greater crested terns at both West Lakes and Middleton.
There have now been 295 confirmed H5 bird flu events in SA alone.
In line with national protocols, the SA government reports H5 bird flu detections as events, rather than individual animal detections.
There are no H5 bird flu detections in poultry or other livestock and authorities say the risk to human health from the virus remains low.
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