Cloudy days, like any weather conditions, can affect the behaviour of birds. Therefore it is worth bird watchers learning more details about whether birds come out when it’s cloudy and if not where they go.
In some ways, cloudy days present challenges for birds. The clouds are a sign of unsettled weather, which generally makes flying difficult for birds. There are exceptions to this rule, like the great frigate birds that use clouds to aid them on transoceanic voyages.
Birds benefit from cloudy days as well. This kind of weather reduces the glare of the sun that can blind smaller birds to the presence of predators, though some sneaky predators can use clouds to their advantage.
Do birds like cloudy days?
Birds’ level of activity on cloudy days can depend on the overall climate or season.
How cloudy days affect birds in hot weather
If the cloud is a respite from a hot summer sun or tropical heat, then bird watchers may find that birds are active for longer. Instead of needing to regulate their body temperature by retiring to shade, birds can continue their activities of foraging or singing later on a cloudy day.
On really bright days when the weather is hot, birds may choose to operate more in shady areas. They can be more active on days when there is more cloud cover.
This is the case in tropical climates, where birds are less active when it is really hot and humid. In countries where the temperature is generally high, birds make the most of cloudy skies.
Their increased activity makes birds easier for bird watchers to spot during cloudy but day weather in tropical countries.
How cloudy days affect birds in cold weather
If it is a cloudy day in a very chilly climate or during the winter, then the clouds may increase the temperature. In this case the birds benefit from the slight relief from the adverse cold.
In cold winter weather, little birds prefer to be out in sunshine rather than in cloudy conditions. The sun will help them to minimize heat loss and maintain a stable body temperature.
Direct sunlight also helps increase levels of Vitamin D in the oil that birds produce and use to preen their feathers. The warmth of the sun also deters mites and parasites from living in birds’ feathers.
This is a trade-off though, because the low winter sun shining in their eyes impedes their vision. Cloudy days can have an impact on small birds’ behaviour because it is easier for them to see predators when they don’t have the sun shining in their eyes.
Are birds more active on cloudy days?
How active birds are is an important consideration for birders. But along with this goes the question of how easy or difficult it will be to actually see the birds.
Cloudy days can mean that the sky provides an ideal background to see soaring birds of prey. Though they can also be seen silhouetted against clear skies, clouds are often more present on a less windy day and they may enable you to see raptors more clearly.
Clouds are a sign that unsettled weather is on its way. Birds are attuned to the approach of low-pressure weather systems. Low pressure air makes flying more difficult for birds so they may be less airborne at this time.
Can birds fly through clouds?
Birds rely heavily on their vision. When there is poor visibility they are less active.
For instance, though birds will sing before dawn, they don’t start moving around and foraging for food until it is light enough for them to see sufficiently.
Nocturnal birds that fly at night have night vision specially adapted for them to be able to navigate and hunt in the dark. Foggy weather, however, would still hamper their night vision.
LINK – how to see owls
Similarly, when birds are flying in cloudy weather they need to see where they are going. They use landmarks on the ground to navigate, like trees, hills and buildings. If they can’t use these visual references to help them find their way, they would become disorientated.
Large birds, like raptors, use the warm air currents. These give them the thermal lift that makes it easier for them to rise above the ground and soar. They will still fly on cloudy days, but there is no reason for them to fly through the clouds.
The aim of flying for birds of prey is to hunt for animals that they can see on the ground. Flying through or above low-lying clouds would prevent them from spotting movements below them. Expending the energy to fly without being able to hunt doesn’t make sense for them.
Some bird watchers report that they have observed eagles in mountainous areas with low-hanging clouds deliberately using the clouds as cover. The eagles then seemed to be able to dive more effectively on their prey, unseen and from a closer range.
Raptors hunting: the best time of day to see birds of prey in flight
How migratory birds adapt to weather
Migratory birds on long journeys may at times have no choice but to fly through clouds. If they are above the ocean in cloudy weather, with no land available for them to break their journey, then they can only keep flying.
In some cases, though, birds might actually choose to fly inside clouds. The feathers of great frigate birds are not waterproof so they are not able to float on the water to rest, unlike other seabirds.
Ornithologists studying great frigate birds on their transoceanic flights discovered that the birds purposefully flew inside clouds to benefit from the updrafts within.
They are able to maintain their control and orientation even in the more turbulent air currents inside the clouds over the Indian Ocean.
The scientists followed the birds’ flight paths by tracking them with satellite tags. Henri Weimerskirch, the lead author of the research, said that they are the only birds that are known to enter into a cloud intentionally.
https://www.science.org/doi/10.1126/science.aaf4374
https://www.sciencedirect.com/science/article/abs/pii/S0022519318301292
Where do birds go on cloudy days – do they come out?
Different conditions may change the location or activities of birds – some species are more active when it’s cloudy whereas others are less so. Birds can be spotted in any weather, it is just a case of knowing where to look.
What next?
Clouds often spell rain. If the weather does turn from overcast to rainy, is still it worth going bird watching? Won’t all of the birds be sheltering from the rain? Not necessarily. Find out more in our wet weather guides.
What birds do in wet weather: is bird watching in the rain worth it?
Everything you need to know about using binoculars in the rain