Walking with confident steps between the fields, the herd egret is accustomed to searching for its favorite food of insects, worms, mice or small frogs, which usually hides in the folds of the soil, providing a great service to farmers who are trying to confront these creatures that threaten their crops.
"Herd egret" is the unknown name of the bird that spreads throughout the countries of the Arab world and the world, and is called by different names. It is called “bird monkey”, “crane”, or “cowbird”. It has been an important component of the agricultural environment for thousands of years.
Egret bird and garbage
The egret bird did not have enough of his important biological role to survive the environmental threats that affected many other creatures. Over recent years, there have been repeated sightings of the bird, known as “the friend of the farmers”, searching for food among the garbage remnants of city roads, instead of its usual presence in the middle of the fields.
Speaking to “Green in Arabic”, Dr. Naglaa Al-Arabani, assistant professor at the College of Sciences and Human Studies at Shaqra University in Saudi Arabia and assistant professor at the College of Science at Damietta University in Egypt, says that “egret birds” abandon the areas that are sprayed with pesticides, and resort to piles of garbage and waste that is full of decomposing organic materials, in search of worms and insects.
credit: Reuters
The size of the global pesticide market in 2022 reached approximately 20 billion US dollars, with expectations that it will rise to about 30 billion dollars by 2027, according to the statistics website “Statista”.
Several years ago, Al-Arabani participated in a study published by the African Journal of Biological Sciences. The study addressed the effects of environmental pollution on egret birds, and the role they can also play in confronting it.
Speaking to us, Al-Arabani points out that living organisms usually develop biological responses to confront the accumulation of heavy metals in the environment resulting from human activities, and therefore analysis of these responses can be used as a vital indicator of the presence of these pollutants.
The results of the study published in 2019, which dealt with the New Damietta region in Egypt, indicated that egret birds found in industrial areas suffered from a decrease in the number of red blood cells, an increase in the number of white blood cells, and a change in the levels of kidney and liver functions. This means that it is negatively affected by the high concentrations of heavy metals included in the research sample, such as lead, zinc, and cadmium.
The use of herd egrets in assessing the degree of pollution was also supported by a later study published by the journal “Environmental Chemistry and Ecotoxicology” at the end of 2023, which concluded that it could be used as an indicator to measure the presence of persistent organic pollutants (POPS), through analyzing the eggs it lays.
Persistent organic pollutants are toxic substances that remain undecomposed for very long periods, harm the environment, human health and organisms, and are used in various fields such as pesticide manufacturing, according to the United Nations Environment Program website.
An almost universal indicator
According to the study, there are several advantages that qualify the bird to be a “near-global indicator,” including its spread in large numbers in different regions of the world, and that its eggs are relatively large and easy to collect, and it is still off the list of threatened species.
Al-Arabani points out, in her talk to us, that although the “egret bird” is not considered one of the species threatened by the phenomenon of climate change, the resulting rise in temperature has affected its areas of distribution, and made it reach areas that it had not previously inhabited, such as the city of Somerset in England, after the tropical and subtropical regions had the largest share of its habitats.
In addition to the Arab world, the egret is found in eastern and southern Asia, Australia, and in the southern parts of Europe.
The scientist specializing in animal physiology adds that the spread of egret birds in many countries with human and industrial activities in different geographical locations, enables scientists to compare between those countries while “fixing the standard of comparison,” which is the bird itself. This ends up with more credible results.
She continued that the diverse activities of herds can be used to measure pollution in both water and land as it lives in trees on the banks of water bodies such as rivers and canals, and spends most of its time on land, but it lays its eggs in the water.
“Egret birds” and the Stockholm Agreement
The study published in 2023 pointed out that the bird can be used to monitor the implementation of the Stockholm Convention on Persistent Organic Pollutants, which was signed by 186 countries and entered into force in 2004, and aims to prevent or restrict the production and use of these pollutants, including DDT pesticides.
