Photo credit: www.sciencedaily.com

Mapping Global Herbivore Distribution Through Dung Analysis

Recent research has utilized dung records to develop detailed maps of herbivore populations worldwide. In a groundbreaking study published in Nature Food, scientists have illustrated a significant correlation between the presence of dung and grazing pressure, suggesting that the amount of dung found in a given area can provide insights into the abundance of herbivores inhabiting that region.

Often dismissed as mere waste from animals like horses and cows, dung is a vital asset for millions around the globe. It serves multiple roles beyond being a byproduct of livestock; it can act as a biological marker, offering critical information about environmental conditions and the herbivorous fauna in different areas.

Led by Professor David Eldridge from UNSW Sydney, an international team from Australia, Spain, China, and Saudi Arabia has conducted the first comprehensive assessment of dung from both livestock and native grazing species across dryland ecosystems—representing approximately 40% of the planet’s terrestrial surface.

The research identified significant dung production hotspots while simultaneously revealing that livestock and native herbivores such as kangaroos and deer typically occupy different ecological niches.

“Recognizing herbivore distribution is essential for various reasons,” notes Prof. Eldridge. “Understanding this can enhance our comprehension of the grazing sector, including the propagation of bovine diseases. A clearer picture of animal locations allows for more targeted land management practices.”

Enhanced Understanding of Livestock Density

Traditionally, livestock density has been assessed using broad environmental indicators, such as rainfall and temperature, which offer limited accuracy in determining where herbivores are most concentrated. Organizations like the United Nations Food and Agriculture Organisation (FAO) require precise data on livestock populations and their distributions, relying on basic computer models for such estimates.

With the aim of refining these methodologies, Prof. Eldridge and his colleagues investigated a unique approach—one that leverages dung, often considered a byproduct of meat production, as an indicator of animal presence. Dung carries nutrients and has various uses in the construction and cooking industries, particularly in developing nations. “Mapping dung can assist organizations in enhancing their estimates of animal distribution,” states Prof. Eldridge.

Research Methodology and Outcomes

The research involved compiling 50 global datasets detailing dung mass and grazing pressure from a variety of herbivorous animals, including antelopes, sheep, and kangaroos. The analysis confirmed strong positive correlations between dung mass and grazing pressure across almost all datasets.

“These results indicate a robust relationship between dung quantity and grazing activity,” Prof. Eldridge explains. “Knowing the dung volume allows us to infer animal distribution patterns.”

The research team synthesized dung data from 760 dryland sites worldwide, creating high-resolution maps that reflect independent herbivory measurements. Interestingly, the findings revealed that while there is some overlap between the territories of native herbivores and livestock, considerable areas exhibit no interaction. This discrepancy may stem from competition for resources or the tendency of wild herbivores to avoid areas where livestock might introduce diseases.

Hotspots of notable dung production were identified in regions such as central Africa, northern and eastern Australia, the Eurasian grasslands, parts of India, and the western United States. In contrast, lower dung production levels were observed in regions like north-central Africa and west-central China.

Dung’s Role in Scientific Research

A global understanding of livestock distribution plays a crucial role in land use planning, estimating methane emissions, predicting meat production, and assessing risks for livestock from diseases like brucellosis. This research bolsters organizations’ abilities to forecast trends in global food production and evaluate the impact of climatic and natural disasters on food security.

Counting dung can also be a more efficient method than counting the animals themselves, according to Prof. Eldridge. “For instance, research has shown that dung counts can provide more accurate estimates of elephant populations than aerial surveys.” It serves as a valuable tool for understanding habitat preferences of elusive species and informs farmers where to strategically position resources like fences and watering points to optimize livestock management.

However, assessing dung presents specific challenges, as noted by Prof. Eldridge. “In some regions, particularly in Asia and Africa, farmers collect dung, which can limit field assessments and lead to underestimations of dung production.” Other complexities arise because certain herbivores, like deer, may bury their dung, and in tropical climates, decomposition by dung beetles and termites occurs rapidly, complicating assessments.

Despite these hurdles, the study provides a pioneering global perspective on dung from both livestock and wild herbivores in dryland areas, offering a pathway for organizations to integrate dung data into their livestock distribution models.

Source
www.sciencedaily.com