The status of bears in the Apennines
Great potential, but a fragile fate
The first attempts to quantify the number of bears actually present in the Abruzzo, Lazio and Molise National Park (PNALM) date back to between the 1970s and 1990s.
In those years, the presence of bears was essentially limited to the area of the PNALM, with a number of individuals varying between 100 and 40, depending on the sources. It is difficult to say with certainty what happened in the population during that twenty-year period, as the methods used to count the bears were still rudimentary. With the advent of innovative non-invasive genetic techniques, in the decade between 2004 and 2014 researchers were, however, able to produce more reliable numbers, showing that over this period the population had remained stable at around 50 bears. A small population in terms of numbers, but with a medium to high density (about 4 bears per 100 km2) and composed mainly of adults (about 60% of bears) with a positive balance in favour of females.
Counts of bears made from the 70s to today. Only after 2004, the introduction of new methods made it possible to produce more accurate data and the degree of precision of each count. The vertical bars represent the uncertainty around the point value.
In the same time frame, researchers also produced the first map of bear distribution in the central Apennines. Despite the generally high level of environmental suitability documented in the Apennines, the bear’s range only extends for about 5422 km2, with a core area of stable presence limited to little more than the area of the PNALM, including the buffer zone and some external areas (about 1460 km2), with an additional peripheral area extended as far as the Sibillini (about 3962 km2) where a few itinerant males are occasionally reported. Until 2014, the presence of family units, in other words, females capable of reproducing, was limited to little more than the area of the PNALM. Research conducted by biologists, geneticists and statisticians has identified the main causes of this lack of numerical growth and geographical expansion as the low number of females reproducing each year in the population, the cubs’ high mortality rate during the first year of life and the excessive levels of mortality in adult females.
A female of bear hit by a vehicle and killed in Molise in 2019.
Each breeding season, this small population makes the most of all its resources in order to reproduce
Every summer for more than 10 years since 2006, researchers, technicians and volunteers have been working together to obtain information on the reproductive capacity of the population. From 2006 to 2014, 1-6 females with offspring were recorded each year in the PNALM, in 70% of cases associated with 2 or 3 young, with a total of 3 to 12 newborn cubs each year. So it only takes one hand, two at most, to count all the females breeding in the core area. This figure is not surprising, as it is a small population, with females accounting for just over half. Considering that bears do not breed every year and excluding young females, it is rare to expect more than 4 or 5 females to give birth each year. Despite these efforts, the average number of female cubs a mother manages to raise each year (known as the reproduction rate) is just 0.18, one of the lowest known in Europe and beyond. How can a female give birth to less than one cub per year? This is explained by the fact that females do not reproduce every year. Births are usually between 3 and 4 years apart. It can also take more than 6 years for a female to give birth for the first time and it seems that some females may not reproduce for as long as 10 consecutive years. What’s more, half the cubs born do not survive until the following year, very low values compared to other brown bear populations. Considering all these facts together, the breeding times for Apennine bears mean that the death of a reproductive adult female bear leaves a void that a female cub may take as long as 12 years to fill. If you consider that survival after the first year of life can’t be taken for granted, that time may be even longer.
Zoologist Paolo Ciucci tells us about bears and numbers.
Being so many and so closely related may not work in the bears’ favour
A number of hypotheses may explain these numbers. Every living species has its own self-regulating systems to ensure that the number of individuals tends not to exceed certain critical values, thus reducing, for example, competition for food. Infanticide by adult males and inhibition of subordinates’ reproduction by dominant females are both systems employed by bears in large populations in Scandinavia and Alaska. Cases of proven or suspected infanticide have also been documented in the last ten years in the Apennines. Although bears have probably reached their maximum numbers in the core area, the generally good health of the individuals captured, both in the past and recently, the rich and diversified diet observed in individual animals, the small size and wide overlap of the territories and the females’ ability to give birth to up to three cubs in a year mean that undernourishment can be excluded as a reason for the bears’ failure to survive or reproduce . It cannot, however, be ruled out that the high rate of inbreeding among Marsican bears may be responsible for the occurrence of birth defects, diseases and congenital malformations that weaken the newborn cubs or reduce the females’ fertility.
On a May afternoon, a female bear emerges from the woods with her two cubs in tow. It is the first time the sow has taken her cubs out of the den, where they were born. To do this, she has chosen a quiet, rugged area where neither humans nor other bears should bother them until the cubs are able to follow her on her journeys. All hope for this small Apennine population rests with these experienced females.
E’ nella sopravvivenza delle femmine adulte che si gioca il futuro dell’orso
Estimated at 13 to 14 in any year, many experts consider the number of reproductive adult females to be extremely low, especially when compared to the number of females that die each year. From 1970 to 2014, an average of 2 to 3 juvenile and adult bears were found dead each year, including at least one female more than a year old. This corresponds to a mortality of about 6% of the females counted in this population, excluding youngsters from that year. Considering that some authors believe the observed mortality (based on bears found dead by chance) could be up to two times lower than the actual mortality (how many were not found?), these values would seem to be incompatible with a growth in numbers. This scenario has also been confirmed by a recent study published in 2017. This showed that, based on current survival data for adult females in the Apennines (between 0.87 and 0.95), the population might even decrease over the next 100 years and risk extinction (with a probability of 20%). This scenario is even more serious when you consider that more than 80% of bears found dead have died from human-derived causes such as poaching, poisoning, or road and rail accidents. The same study shows the population to be highly susceptible to catastrophic events (mass mortality events) which could triple the risk of extinction if repeated over time, even several decades apart. However, a positive element also emerges. An increase of even 2% in the survival of adult females would ensure that numbers can grow and bears survive for the foreseeable future.
Changes in the number of reproductive females, family units and year-old cubs observed each year in the PNALM and SPA/buffer zone. The number of females found dead each year is also reported.
There have been some positive signs over the last few years, but we must not lower our guard
Thanks to activation of a monitoring network involving not only the protected areas, but also the regional authorities and the Carabinieri Forestali, since 2014, the technicians and researchers who continue to monitor bears inside and outside the Park are witnessing a very encouraging phenomenon. The number of females breeding each year in the core area (3 to 9 females) and the number of cubs born (6 to 16 cubs) are higher than the average observed in previous years. In 2019 in particular, partly thanks to the great abundance of beech nuts recorded in 2018, nine family groups were counted in the core area for a total of 16 cubs born, values among the highest ever observed. What’s more, since the end of 2014, between 1 and 4 females with cubs have been frequenting areas outside the stable core area (even as far as 30-40 km away), with a total of at least 13 adult females and at least 19 newborn cubs outside the PNALM. At the same time, the number of males in peripheral areas also indicates an increasing and stable presence.
These data suggest that in recent years new reproductive females have been recruited into the population in the core area, but above all that the territory is expanding and numbers are growing in new territories. However, it must be remembered that mortality levels have not changed in recent years. One to two females continue to die each year inside and outside the PNALM, including a female with a year-old cub, run over in 2019 on a provincial road on the edge of the PNALM buffer zone. Although the Park is still the stronghold for saving bears, their future lies outside. In order for the population to really grow, the females must conquer new territories and establish new populations.
In the Apennines, there is room for more than 200 bears. To save bears, the big challenge is to reduce the risks they will face.