The arrival of bitterly cold weather – only a few days before the vernal equinox, the official start of spring in Britain – could have serious consequences for wildlife, experts have warned.

The snow and biting winds, which led to the cancellation of flights and disrupted road travel, will reduce the insect population, creating food shortages for birds and other creatures.

Migratory birds, such as the wheatear and the sand martin, are now arriving in Britain in numbers, the experts have pointed out, and will need food after long flights from the south. Insects are their principal source of nourishment.

In addition, there had been sightings of butterflies and bees making the most of last week’s warm weather, and these could be badly affected by the sudden arrival of cold and snow.

Frozen lakes and ponds could also affect frogs and other amphibians, say wildlife experts. “There are also fears for ravens, tawny owls and blackbirds who have already begun nesting,” said Met Office spokesman Grahame Madge.

Forecasters said snow, feeding in from the North Sea, started to spread westwards across to the Midlands and parts of Wales on Saturday. By the end of the day, most places had seen some snow, with gusty winds bringing bitterly cold temperatures. More snow is expected on Sunday, especially in south-west England, where as much as 25cm could fall on higher ground.

Travel disruption is likely, rural communities could become cut off, vehicles may be stranded and power cuts could occur, forecasters have warned.

“It will be bitterly cold with some snow for many places over the weekend,” said Met Office meteorologist Alex Burkill. “There are some very strong winds, meaning it could feel as low as -7C or -8C for some people.”

The arrival of the cold weather has brought a repeat of the disruption caused by the “beast from the east” storm that hit Britain two weeks ago. However, Met Office officials said they expected this weekend’s chaos would be over by Tuesday.

An amber weather warning for snow and ice was put in place across north-west England, Yorkshire and the Midlands, as well as London, the south-east, and the east of England, while a less severe yellow warning for snow and ice was issued for most of the rest of the country.

The lowest temperature on Saturday morning was recorded near Carter Bar on the Scotland-England border, at -2.6C.

Network Rail said it was going to run empty trains overnight to help keep the network clear of snow. However, it warned that disruption was possible. Motorists have been urged to be prepared before setting out on journeys this weekend, with Highways England advising them to avoid trans-Pennine roads if possible.

Highways England’s head of road safety, Richard Leonard, said gritter lorry drivers would be working “around the clock”, though he also stressed it was important for drivers to take care. “Make sure you keep your distance and reduce your speed if you need to travel, because, even in conditions that seem normal and when the snow is not settling, it can be slippery if ice patches have formed or where fresh salt has not been worked into the carriageway.”

Most cancellations at Heathrow on Saturday were on short-haul flights, but British Airways said some transatlantic flights had been affected. Lufthansa, Aer Lingus, TAP Air Portugal and KLM also made cancellations. “While this weekend’s weather may result in minor delays and some airlines consolidating flights, significant disruption at Heathrow is not currently expected,” said a spokesman. “We are working closely with our on-site Met Office to monitor the further snowfall expected throughout the weekend. As always, we advise passengers to check their flight status with their airline before coming to the airport.”

In the north of England, strong winds led to the cancellation of the annual Boat Race of the North, which sees rowing teams from Durham and Newcastle universities compete against each other on the River Tyne, the BBC reported. Conditions on the A1 left the Durham team unable to transport its boats on their long trailers.