Q: What do confused magpie geese, skewed sex ratios in crocodile hatchlings and disappointed anglers have in common?

A: All are possible impacts of the missing Top End wet season on nearby wetlands, sites of important environmental significance and rich ecological diversity alike.

As the dry conditions persist, ecologists and researchers spoke about its impact on the creatures, big and small, that dwell in the wetlands.

Losers – magpie geese

Flocks of the lean and lanky bird gathering on patches of well-irrigated grass around Darwin may be confused by the weather, and that could be interrupting their breeding patterns.

Magpie geese fly long distances and breed in wetlands. ( ABC Radio Darwin: Jesse Thompson )

Not much is known about their precise movements, but Rebecca Rogers, a PhD candidate at Charles Darwin University, said she expected more of them to be breeding on floodplains.

Instead, her research, which involves mapping the waterfowls' movement with tracking collars, has turned up some peculiar travel patterns.

"We've even had some that have flown all the way out to floodplains, 50 to 100 kilometres, then come all the way back, and they've done that a couple of times."

Because of a lack of long-term data, it's difficult to say for sure how significantly this pattern differs from normal.

"But we have seen them do it a few times, which I didn't really expect because it is a long way to fly and a lot of energy for a big bird to use just to come back again," Ms Rogers said.

Magpie geese migrate to Northern Territory wetlands. ( Supplied: Field and Game NT )

One theory is that the lack of rain has restricted the February-to-June breeding season; another holds that the bouts of heavy rain, which is their signal to begin migrating, simply haven't arrived.

It's certain, though, that many of the city-dwelling birds aren't yet breeding.

Annual government surveys of magpie geese populations are used to inform bag limits during the following hunting season, so it's possible the 2020 season may bear the brunt of the missing rain.

Neutral – crocodiles

When it comes to crocodiles, scientists are keeping an eye on the sex ratio of hatchlings.

That's because despite their reputations as fearless, vicious predators, incubating crocodiles are actually sensitively attuned to the environment.

Whether they hatch as males or females comes down to minute variations in the environmental temperature.

The sex of crocodile hatchlings is determined by the egg incubation temperature. ( ABC Capricornia: Megan Hendry )

"If you incubate an egg at 32 degrees all the way through, you'll get a male; on either side, you'll get a female," said Charlie Manolis, chief scientist at crocodile tourism research venture Crocodylus Park.

"Almost certainly those warm conditions, early in incubation, have led to some of those nests producing more males than they may have on a normal year."

Researchers have also witnessed a higher mortality of eggs, as embryonic crocodiles die in the hot, dry conditions.

Incubated eggs need to be kept at precise temperatures in high humidity. ( ABC Radio Darwin: Jesse Thompson )

"Thirdly, you can actually get animals that get all the way through incubation but will have kinked spines, bent tails and deformities that will invariably lead to death as well," Mr Manolis said.

Despite this, he believed the overall population was unlikely to register a long-term impact, in part because the mortality rate of wild crocodile hatchlings remained high, and also because their long-term survival showed them to be adaptive, resilient creatures.

More likely to be impacted are the crocodile egg collectors and farms who may be finding lucrative crocodile embryos have died in their eggs.

That may cause a hiccup getting high-quality skins to the luxury fashion houses they supply.

Losers – barramundi (and fishers)

The missing wet also brings bad news for fishers, according to Alison King, an associate professor of ecology, whose analysis shows the quantity and growth of juvenile barramundi improves during significant wet seasons.

Heavy rain makes floodplains more nutrient-rich and allows fish to travel more widely to spawn.

"Conversely, when we get a poor wet season like this, we tend to get poorer numbers of young and poor growth rates," she told ABC Radio Darwin's Liz Trevaskis.

"So we're predicting, based on our data at the moment, that this year when we go back out in a few months' time, we won't see high numbers of juvenile barramundi in the system."

As with other species, it would take multiple poor wet seasons to register a significant impact on the population.

Less rain means fewer juvenile barramundi and poorer fishing. ( ABC News: James Bennett )

For now, expect some disappointing fishing.

"Some of the anglers are probably attuned to this, but it's probably pretty likely that it's going to be a poor year for run-off fishing as well," she said.

"The big barra getting out onto the floodplains just hasn't happened ... so that run-off fishing isn't going to be a bumper time this year compared to some of our recent years."

Winners – small freshwater fish

The prognosis isn't all bad for freshwater fish.

"Our freshwater fish in the Top End are a really diverse fish fauna and most of them have a whole range of strategies to really keep resilient in these sort of tough times," Associate Professor King said.

Wetlands in Kakadu are known to be sites of rich environmental diversity. ( Supplied: Australian Conservation Foundation )

However, her preliminary data suggested some smaller species favoured drier conditions.

"They actually have boom times when we get poorer wet seasons," she said.

"Obviously you've got these big raging waters that are high velocity or high water flow, and that can disrupt some fish that can't really get out of those events."

The amount of rain that falls in the wet season strongly dictates water levels in wetlands habitats during the dry season, she said, so the effects were likely to continue in the months to come.