European Bird Populations Threatened by Intensive Farming, Study Finds

Intensive farm­ing in Europe might affect bird species and pop­u­la­tion num­bers more than pre­vi­ously thought.

A new study pub­lished in PNAS, a peer review sci­en­tific jour­nal of the U.S. National Academy of Sciences, con­sid­ers a mas­sive amount of data retrieved in 28 European coun­tries across 37 years.

A team of inter­na­tional sci­en­tists assessed 170 com­mon bird species in 20,000 dif­fer­ent sites and researched how those species reacted to four sources of anthro­pogenic pres­sure: urban­iza­tion, change in for­est cover, tem­per­a­ture change and agri­cul­tural inten­si­fi­ca­tion.

In the area being con­sid­ered, researchers found that farm­lands’ birdlife dropped by 60 per­cent in the four decades from 1980 to 2016.

The researchers’ goal was to estab­lish the extent of the bird pop­u­la­tion decline and to uncover the rela­tion­ships among those four dif­fer­ent pres­sures and their com­bined impacts on birdlife. Intensive farm­ing was sin­gled out as the most impact­ing pres­sure.

European Union offi­cial data show that almost 40 per­cent of the E.U. is ded­i­cated to agri­cul­ture. According to the researchers, such exten­sive farm­land helps explain its poten­tial impact on birdlife.

The new research mea­sured inten­sive farm­ing as the cover of farms with high input of pes­ti­cides and fer­til­iz­ers.

“Among the rea­sons for the sharp decline in birds pop­u­la­tion as inten­sive agri­cul­ture expands, there is the sig­nif­i­cant drop in avail­able prey, such as insects,” Federica Luoni, a bio­di­ver­sity man­age­ment and pro­tec­tion sci­en­tist at the Italian Association for the Protection of Birds and Nature (Lipu), told Olive Oil Times.

“Previous research, such as a recent study in Germany, showed how in the last 20 years, there were areas where the insect pop­u­la­tion dropped by 80 per­cent,” added Luoni, who is not directly involved in the new research.

Crucial insects such as pol­li­na­tors are directly affected by the wide­spread use of chem­i­cals in agri­cul­ture.

“We are reach­ing the point where some are plan­ning man­ual or mechan­i­cal pol­li­na­tion oper­a­tions where the wild insect pop­u­la­tion can­not guar­an­tee pol­li­na­tion any­more,” Luoni explained.

According to the study, inver­te­brates are a cru­cial part of many bird species’ diets, espe­cially at spe­cific stages of their devel­op­ment. Of the 170 species con­sid­ered, 143 depend on insects dur­ing breed­ing.

The researchers wrote that a highly cur­tailed insect pop­u­la­tion will likely affect repro­duc­tion, parental behav­ior and nestling sur­vival ​“in addi­tion to direct con­t­a­m­i­na­tion by seed con­sump­tion and trophic accu­mu­la­tion with sub­lethal effect.”

“Chemicals indi­rectly hit birdlife by slash­ing avail­able prey,” Luoni said. ​“But they also affect birds directly, pro­vok­ing acute intox­i­ca­tion or, more fre­quently, chronic intox­i­ca­tion. Those are caused by sev­eral dif­fer­ent mol­e­cules such as neon­i­coti­noids and oth­ers that are under inves­ti­ga­tion.”

According to Luoni, in a coun­try widely praised for its bio­di­ver­sity, such as Italy, bird num­bers in agri­cul­tural areas have dropped by 30 per­cent since 2000. If only plains are con­sid­ered, where most inten­sive farm­ing is done, the drop exceeds 50 per­cent.

Considering the four anthro­pogenic pres­sures, the new research found inten­sive agri­cul­ture has broader effects in the west­ern regions of Europe, where it has been expand­ing faster. Of the 50 bird species affected by inten­sive farm­ing, 31 were neg­a­tively affected.

“We find a mostly neg­a­tive influ­ence of high-input farm cover not only for farm­land species but also for species with a diet at least partly based on inver­te­brates dur­ing the breed­ing sea­son, long-dis­tance migrants, and wood­land birds, i.e., a vast major­ity of the com­mon birds,” the researchers wrote.

The research also hinted at how large agri­cul­tural oper­a­tions use inten­sive farm­ing prac­tices more than smaller ones. Data show that birdlife fares bet­ter in coun­tries where small farms are the norm.

The study showed how bird species reacted evenly to the pres­sure fac­tors. For instance, ris­ing tem­per­a­tures neg­a­tively impacted 27 species, while 28 seemed to ben­e­fit from those changes.

Scientists also found that expand­ing for­est cover affected nine species and ben­e­fited 16.

“Forest cover often expands in areas where agri­cul­ture is not prof­itable any­more, areas that end up being mostly aban­doned,” Luoni said. ​“While this might ben­e­fit some wood­land species, it also reduces those open mead­ows cru­cial for other species.”

While some species may profit from changes trig­gered by human activ­i­ties, the over­all num­ber of birds fol­lows a trend of sharp decline.

Whereas the farm­land bird pop­u­la­tion dropped by almost 60 per­cent, other bird pop­u­la­tions were hit by a slower decline. Woodland bird num­bers dropped by 18 per­cent, urban dwellers by 28 per­cent, cold dwellers by 40 per­cent and hot dwellers by 17 per­cent.

“To counter these trends, it is cru­cial to estab­lish and fol­low good agri­cul­tural prac­tices,” Luoni said. ​“That means an approach to agri­cul­ture which must be based on agroe­col­ogy, where sus­tain­able farm­ing works with nature.”

According to Luoni, the increase in organic farm­ing in some areas pro­vides hope for the future.

However, the authors of the new research warned that fur­ther stud­ies are needed to fully under­stand the deep casual rela­tion­ships among the dif­fer­ent anthro­pogenic pres­sures and bird num­bers decline.

They also under­lined how cru­cial data are often under-reported by local and national insti­tu­tions. Still, they noted how their study pro­vides evi­dence of the agri­cul­tural prac­tices’ impact on a con­ti­nen­tal scale.

“Considering both the over­whelm­ing neg­a­tive impact of agri­cul­tural inten­si­fi­ca­tion and the homog­e­niza­tion intro­duced by tem­per­a­ture and land-use changes, our results sug­gest that the fate of com­mon European bird pop­u­la­tions depends on the rapid imple­men­ta­tion of trans­for­ma­tive change in European soci­eties, and espe­cially in agri­cul­tural reform,” the researchers con­cluded.

• European Commission