How Long Do Great Blue Herons Live?

The life expectancy of birds is known to be closely related to their size. So as the biggest heron species in North America, how long do great blue herons live? The average life expectancy for these large birds is around fifteen years. However, surviving their first year is no easy task.

The Size-Age Connection

Great blue herons reach heights of four and a half feet and can have wingspans of up to six and a half feet wide. As a general rule, it’s accepted that the size of a bird correlates to its lifespan. So it’s no wonder great blue herons have a much longer lifespan than most smaller birds.

In fact, the oldest great blue heron on record is believed to be at least twenty-four. Flamingoes are another example of this general rule as these tall birds have an average lifespan of thirty years or more.

The Dangers Young Herons Face

While great blue herons live to an older age than many other bird species, there are also many perils and challenges they must face early on and often even before even hatching. Despite the fact that herons typically lay from three to six eggs in an average brood only two young herons on average will survive.

Herons are extremely sensitive when nesting and may abandon nests, young, and breeding colonies if they are disturbed by humans. While adult herons don’t have many predators once full-grown, many animals eat young herons and heron eggs. Predators such as raccoons, opossums, minks, and alligators are common threats among a handful of others.

Eagles in particular are a big threat, especially bald eagles. And just like when disturbed by humans, when there is a persistent eagle threat herons may abandon their nests completely.

In times when food is hard to find the weakest hatchlings typically die of starvation and then there is always the threat of simply falling out of the nest. Cold weather, windstorms, and heavy rain during hatching also commonly cause the death of baby herons.

High-Mortality Rate

Things don’t get any easier for young herons, at least not at first. Past studies on banded great blue herons in North America have shown that after leaving the nest the mortality rate for the first year of their life is around seventy percent. These are usually due to mistakes made because of the birds’ lack of experience. However, after the first year, the death rate decreases steadily.

Challenges Of Adult Herons

As adults, great blue herons have few predators, because of their large size and sharp beak they are simply too much to handle for most animals. However many herons are killed each year and often illegally by humans. Herons primarily eat fish which can cause them to get into trouble when it comes to stealing fish from commercial fish farms and backyard ponds.

There are a few ways to efficiently and humanely deter herons such as by using a heron decoy for example. Decoys trick these territorial feeders into thinking that another heron has already claimed the area, so they won’t land. However, a bullet is unfortunately sometimes used instead.

Because herons are at the top of the food chain they are affected by toxins. While we don’t know the full effects of the toxins on adult birds it does affect their reproduction. Mercury, selenium, and PCBs, in particular, have been proven to cause their eggshells to become too fragile to survive normal incubation.

Last but not least draining wetlands and the loss of other feeding habitats for development can drastically impact the reproduction rate of local heron populations. This is due to the fact that the number of breeding great blue herons is directly related to the amount of feeding habitat available.

Great blue herons are special and unique birds. While they can be considered pests in some circumstances deterrents are always the best solution. And to help ensure great blue herons live as long as possible feeding habitats and breeding areas need to be protected.

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