Birds flying high during storms is a common phenomenon that many people have observed. There are several reasons why birds may exhibit this behavior before, during, and after storms:
To Avoid Turbulence
One of the main reasons birds fly higher in advance of storms is to avoid turbulence caused by changes in air pressure. As a storm approaches, the air pressure drops and the wind speed increases. This creates instability and turbulence, making it harder for birds to control their flight lower to the ground. By gaining altitude, birds can fly above the turbulent lower air levels of the approaching storm.
How high do birds fly to avoid turbulence?
Research shows that many species of birds will ascend anywhere from 300 feet to over 3000 feet higher to escape turbulence before and during storms. The exact altitude depends on the size of the bird and strength of the approaching storm. For example, a study of GPS-tagged vultures in South Africa found they ascended up to 3,280 feet higher in advance of approaching storms.
To Gain a Wider Field of View
Another reason birds fly higher in stormy conditions is to gain a wider view of their surroundings. From a greater height above ground, birds can see emerging threats more easily, such as approaching fronts, rain shafts, and downdrafts. A wider field of view helps birds navigate more effectively through and around inclement weather.
How much further can birds see from greater heights?
The maximum viewing distance for a bird from an elevated position depends on the species’ visual acuity. For example, an eagle soaring at 1,000 feet above ground may be able to spot prey up to 2 miles away or further. Other bird species would gain a wider field of view as well, perhaps hundreds of feet to a mile further from an elevated perch hundreds of feet above ground level.
To Locate Thermals and Avoid Sinking Air
Birds will also fly higher to locate thermals, or columns of rising warm air. Thermals provide free lift for soaring birds, allowing them to gain altitude and conserve energy. By riding thermals above storms, birds can avoid downdrafts and sinking air which could lead to turbulence or cause them to lose altitude.
What altitudes do birds find the most effective thermals?
For smaller birds, the most effective thermals are often located a few hundred feet up, while for larger raptors, the strongest thermals can be thousands of feet above ground. Birds will pattern the altitude of their soaring flight to make the most of the rising air columns above storms and terrain.
Bird Type | Typical Thermal Soaring Altitudes |
---|---|
Small birds (swallows, swifts) | 300 – 1,000 feet |
Large raptors (eagles, hawks) | 1,000 – 6,000 feet |
To Conserve Energy
Staying aloft takes a lot of energy for birds. Flying higher where thermals are stronger enables them to soar and reduce energy expenditure. This is especially important in storms, when precipitation and strong winds make flying conditions more challenging at lower altitudes. Riding thermal updrafts allows birds to stay aloft with minimal effort exerted through flapping flight.
How much energy do birds conserve by soaring in thermals above storms?
Research on large birds shows they can reduce energy costs by up to 96% when soaring in thermals versus flapping flight alone. For smaller birds, energy savings could be 50% or more by utilizing updrafts above storms for lift versus constantly flapping. Overall, the height and strength of thermals above storms and terrain allows most birds to dramatically cut their energy expenditure.
To Avoid Lightning Strikes
Electrocution is a serious threat to birds flying through storms. Birds struck by lightning in flight are often killed or severely injured. Flying at higher altitudes above a storm helps birds steer clear of dangerous convective updrafts and reduce their exposure to potential lightning strikes.
What is the typical altitude birds must fly to avoid lightning strikes?
Experts estimate birds should ascend to at least 3,000 feet above ground or top of thunderstorms to reduce lightning risk. This rule of thumb provides a safe buffer above even the highest convective updraft columns where lightning often originates within storms. Flying below this zone puts birds at greater risk, especially if they are attempting to cut through heavy precipitation and downdrafts.
Height of Storm Front | Recommended Minimum Flight Altitude |
---|---|
1,000 feet | 3,000+ feet |
5,000 feet | 7,000+ feet |
10,000 feet | 12,000+ feet |
To Take Advantage of Tailwinds
Storm systems bring winds that birds can utilize to their advantage. By climbing to altitudes where storm winds prevail, birds can gain tailwinds that give them extra speed and assistance on their migratory journeys. Winds blowing in the same direction as a bird’s path provide an energizing boost compared to headwinds or calm air.
How much faster can birds fly when assisted by storm tailwinds?
Research shows migratory birds can nearly double their airspeed when aided by moderately strong tailwinds at high altitudes. For example, raptors may cruise at 40-50 mph in calm winds, but speeds upwards of 90 mph have been recorded in tailwinds created by storms. Gaining altitude helps birds take full advantage of these favorable winds for faster passage.
To Fly Above Poor Weather
By gaining altitude, birds can fly above lower lying areas of rain, snow, fog, and low cloud cover. This gives them a better chance of finding clearer airspace, allowing safer passage over and around storm systems. Birds will instinctively seek altitudes that provide the best navigational conditions above or between weather hazards.
What altitude is needed to fly over various weather conditions?
The altitude birds need to clear poor weather depends on the type and extent of the conditions below:
Weather Condition | Typical Minimum Altitude to Clear |
---|---|
Low fog | 300 feet |
Rain showers | 1,000 feet |
Snow showers | 2,000 feet |
Low cloud ceiling | 3,000 feet |
Gaining 1,000 feet or more in altitude greatly improves chances of finding better visibility above ground weather. This allows safer navigation for birds displaced by storms.
Conclusion
In summary, birds fly to higher altitudes before, during, and after storms for several critical reasons: to avoid turbulence, gain a wider view, locate thermals, conserve energy, steer clear of lightning, utilize tailwinds, and escape lower hazardous weather. Instinct and experience guide birds to ascend hundreds or thousands of feet to find the best flight conditions and safety above storm systems. Understanding this behavior provides insight into how birds skillfully take advantage of wind patterns and air space when navigating through tumultuous skies.