Early "Homo sapiens" facilitated the establishment of the Bonelli's eagle in the Mediterranean 50,000 years ago - Canal UGR
Not only is there no sign at all that the conversion of leading biologists to creationism's childish fairy tale in place of the scientific Theory of Evolution, that creationist cult leaders have been assuring their dupes is imminent - and has been for the last 50 years or so - it's as though they've never even heard of it. They still keep finding evidence of events that happened ten of thousand, even tens of millions of years before the Universe existed, according to the ludicrous creation myths they are supposedly about to adopt. And those events are frequently evidence of evolution or recent human history.
Imagine a serious, grown-up scientist who has been through university, with so much contrary information at his or her fingertips believing that account of magic creation 10,000 years ago written by ignorant Bronze Age pastoralists yet belonging to the creation cult requires fools to believe such an absurdity.
About 9 months ago while on holidat near Bezier, France, we were driving to Carcassonnes when, about a mile apart, we saw two majestic eagles that neither of us recognised. I now know they were Bonelli's eagles, and I probably have the activities of early Homo sapiens about 40,000 years ago to thank for them being there.
A study led by scientists from the University of Granada (UGR), Spain, shows how the activities of early Homo sapiens in the Iberian Peninsula, 40,000 years before creationists think their god created a universe consisting of a small, flat planet with a dome over it in the Middle East, may well have facilitated the expansion of the range of Bonelli's Eagle, Aquila fasciata, north of the Mediterranean Basin.
Tell me all about the evolution and range of Bonelli's Eagle, Aquila fasciata, please. Bonelli's Eagle (Aquila fasciata) is a medium-sized bird of prey found in various regions across Europe, Africa, and Asia. The species is notable for its adaptability to different habitats and its striking hunting prowess. Here is a comprehensive overview of the evolution, range, and general characteristics of Bonelli's Eagle:The team believe they have shown that in the competition between Golden eagles and Bonelli's eagle, in which Bonelli's eagle normally comes off worst, human habitation, which Golden eagles avoid, allowed Bonelli's Eagle to become established in coastal areas of Spain, Italy and Greece.
Evolution
Bonelli's Eagle is part of the Accipitridae family, which includes hawks, eagles, and kites. The evolutionary lineage of Bonelli's Eagle, like other members of the Aquila genus, can be traced back to the Miocene epoch, roughly 23 to 5 million years ago. Over millions of years, these birds have adapted to a variety of ecological niches, leading to the diversification of the genus Aquila. The genus name "Aquila" is derived from the Latin word for eagle, emphasizing their status as true eagles. Bonelli's Eagle has developed several adaptations that make it a formidable predator, including powerful talons, keen eyesight, and a robust flight musculature.
Range and Distribution
Bonelli's Eagle has a wide distribution across three continents:
- Europe: In Europe, Bonelli's Eagle is found in the Mediterranean region, including Spain, France, Italy, and Greece. The populations here are relatively isolated and are considered vulnerable due to habitat loss and human interference.
- Africa: The African range of Bonelli's Eagle extends across North Africa, from Morocco to Egypt. They inhabit mountainous regions and semi-deserts, adapting well to the arid conditions.
- Asia: The Asian range is the most extensive, covering regions from the Middle East, including Israel, Jordan, and Iran, to South Asia in India, Pakistan, and further east to China and Southeast Asia. In these areas, the eagles are found in diverse habitats, including forests, open woodlands, and mountainous regions.
Habitat
Bonelli's Eagle prefers rugged terrains such as cliffs, rocky outcrops, and mountainous regions, which provide excellent nesting sites and vantage points for hunting. They can also be found in open woodlands, semi-deserts, and savannas, demonstrating their adaptability to different environments. These birds are known to build large nests on cliffs or in tall trees, often using the same nest site for many years.
Physical Characteristics
Bonelli's Eagle is characterized by its striking plumage and robust build:
Diet and Hunting
- Size: They typically range from 55 to 65 cm (22 to 26 inches) in length, with a wingspan of about 150 to 180 cm (59 to 71 inches).
- Plumage: Adults have dark brown upperparts and a white underside with dark streaks. Juveniles are generally lighter with more rufous tones and less pronounced streaking.
- Beak and Talons: They have a powerful hooked beak and strong talons, adapted for catching and killing prey.
Bonelli's Eagles are apex predators with a diet that primarily includes medium-sized mammals and birds. Common prey items include rabbits, hares, pigeons, and partridges. They are also known to hunt reptiles and occasionally other birds of prey. Their hunting technique involves soaring at great heights to spot prey and then executing a swift, powerful dive to capture it.
Conservation Status
Bonelli's Eagle is currently listed as "Least Concern" by the IUCN Red List, but the species faces several threats that could impact its populations:
- Habitat Loss: Urbanization, deforestation, and agricultural expansion have led to habitat fragmentation and loss.
- Human Disturbance: Nest disturbance and persecution by humans, especially in regions where they are blamed for livestock predation, pose significant threats.
- Decline in Prey: Reduction in the populations of key prey species due to hunting and habitat changes affects their food supply.
Conservation Efforts
Efforts to conserve Bonelli's Eagle include habitat protection, legal protection from hunting, and initiatives to monitor and support breeding populations. Conservation programs in Europe have been particularly focused on maintaining and restoring suitable habitats and reducing human disturbances near nesting sites.
Conclusion
Bonelli's Eagle is a remarkable raptor with a significant presence across three continents. Despite facing various threats, ongoing conservation efforts aim to ensure the survival of this majestic bird. Their adaptability and hunting prowess continue to make them an important species in the ecosystems they inhabit.
How they arrived at this conclusion is the subject of an open access paper in the journal People And Nature and is explained in a news release from the University of Granada (UGR):
A study led by the University of Granada (UGR) shows that our ancestors influenced the relationship between Bonelli’s eagles and their main competitors, golden eagles.A plain-language summary of the study is given in the journal's blog:
Paradoxically, the future of the Bonelli’s eagle is now being threatened by human activity.
A team of Spanish and Portuguese scientists led by the UGR have unravelled the ancestral history of one of the most iconic birds of prey in the current Iberian fauna: the Bonelli’s eagle (Aquila fasciata).
The study, published in the prestigious scientific journal People and Nature, combines evidence from several disciplines, including palaeontology, genetics and ecology, to answer questions about when and why the Bonelli’s eagle, a species primarily found in tropical and subtropical areas, colonised the Mediterranean Basin.
As Marcos Moleón Paiz, a Senior Lecturer at the UGR’s Department of Zoology and lead author of the paper, explains:
The Bonelli’s eagle is a ‘newcomer’ to Europe. This species probably began to establish itself in the Mediterranean Basin no more than 50,000 years ago, while others, such as the golden eagle (Aquila chrysaetos), have been here much longer, as evidenced by the fossil record.
Marcos Moleón Paiz, lead author
Department of Applied Biology,
Miguel Hernández University, Elche, Spain
And Department of Conservation Biology
Doñana Biological Station-CSIC, Seville, Spain.
The spatial analysis carried out in the study showed that cold climatic periods are largely unfavourable for the Bonelli’s eagle, but not for the golden eagle.
During the last glacial period, the Bonelli’s eagle could only find refuge in warm coastal areas, which is precisely where the oldest fossils of this species have been found
Marcos Moleón Paiz.
Genetic analysis confirmed that around the Last Glacial Maximum, the Mediterranean population of Bonelli’s eagles consisted of only a few individuals. This ancestral population of Bonelli’s eagles thrived as the temperature in the Mediterranean Basin rose and the human population grew and became sedentary.
However, as Moleón points out:
Once the question of ‘when’ was resolved, the inevitable question arose: Why did Bonelli’s eagle begin to colonise the Mediterranean in such a complex climatic period? And why did it establish itself during the last glacial cycle and not before?
After testing several alternative hypotheses, all of the pieces of the puzzle indicated that the first settlers of our species (Homo sapiens) in Europe played a fundamental role.
In addition, our mathematical models showed that if we were able to eliminate all the existing golden eagle pairs in climatically favourable areas, we would expect to see a significant increase in the number of Bonelli’s eagle pairs, but not the other way round. We also know that golden eagles can kill Bonelli’s eagles and take over their territories, but not vice versa.
Marcos Moleón Paiz.
The role of our ancestors
The study collected and analysed the most comprehensive information currently available on the competitive interactions between Bonelli’s eagles and golden eagles. This enabled the scientists to confirm that the golden eagle is the dominant species and the Bonelli’s eagle is the subordinate species in this relationship. Thus, the results showed that Bonelli’s eagles can only survive in places where golden eagles are rare, which is mainly in areas that are densely populated by humans. It is worth noting that golden eagles are less tolerant of human presence than Bonelli’s eagles. The authors hypothesise that with the arrival of the first anatomically modern humans in Europe, some of the golden eagle territories closest to human settlements were abandoned and these “vacant” territories were then occupied by Bonelli’s eagles from the Middle East.
In short, Bonelli’s eagles could not have established themselves in the Mediterranean before the arrival of the first Homo sapiens because the competitive pressure from golden eagles and other species would have been too overwhelming.
Marcos Moleón Paiz.
Living near or far from humans
Knowledge of the ability of humans to influence species distribution is nothing new. The novelty of this study lies in revealing a mechanism called «human-mediated competitive release», by which our species, including our ancestors, could indirectly affect the distribution of other species, including long-lived species.
In order to understand what we observe in nature today, we often have to look to the past.
Marcos Moleón Paiz.
However, the advantage that living close to humans once gave Bonelli’s eagles has now turned against them.
Paradoxically, the future of the Bonelli’s eagle in the Mediterranean region is currently being threatened by the relentless intensification of human activities in the environment, which is reflected, among other factors, in the deaths caused by power lines, the lack of prey, and the disturbance of nesting sites.
Marcos Moleón Paiz.
Plain Language Summary: Wildlife following people: A multidisciplinary assessment of the ancient colonization of the Mediterranean Basin by a long-lived raptor.For technical details and background to the study, we have the team's open access paper in People And Nature:
By Marcos Moleón, Eva Graciá, Nuria García, José M. Gil-Sánchez, Raquel Godinho, Pedro Beja, Luís Palma, Joan Real, Antonio Hernández-Matías, A. Román Muñoz, Eneko Arrondo, and José A. Sánchez-Zapata.
Understanding what we observe in nature today often requires looking to the past. The Mediterranean Basin is home to the Bonelli’s eagle (Aquila fasciata), a species that has garnered significant attention from scientists, conservationists, and the general public. In our study, we propose that the presence of this species in the region is relatively recent and that its colonization was unintentionally facilitated by early Europeans. By compiling multiple sources of evidence and integrating various disciplines, our objective was to reconstruct the puzzle of the ancient colonization of the Mediterranean Basin by the Bonelli’s eagle and to propose a plausible mechanism that explains the observed patterns.
We found that Bonelli’s eagle fossils were confined to the last 50 thousand years. This timeframe aligns with the arrival of the first anatomically modern humans in Europe. Surprisingly, this suggests that Bonelli’s eagles, a species heavily constrained by low temperatures, began colonizing the Mediterranean Basin during a period considerably cooler than the present. Genetic data confirmed that the population of Bonelli’s eagles was very small during the last glacial maximum, which occurred approximately 27 to 19 thousand years ago.
But, why did Bonelli’s eagles arrive around 50 thousand years, and not earlier during preceding inter-glacial periods that were climatically favorable for this species? To address this question, we also investigated the competitive interactions between Bonelli’s and golden eagles (A. chrysaetos) in present-day ecosystems. Our observations revealed that Bonelli’s eagles faced limitations due to the dominance of golden eagles. In the absence of golden eagles, we could expect a proliferation of Bonelli’s eagle pairs; however, the reverse scenario does not hold true. Nevertheless, Bonelli’s eagles exhibit significantly higher tolerance towards human presence, enabling them to inhabit humanized areas that are free from their larger competitors.
Thus, our findings align with the human-mediated competitor release hypothesis, by which anatomically modern humans could have unintentionally favored the large-scale colonization by Bonelli’s eagles of a previously competitively hostile Mediterranean Basin. In other words, Bonelli’s eagles could not have established in the Mediterranean until the arrival of humans, which indirectly created an increasing number of patches free from competition with larger eagles. Paradoxically, the initial advantages of living near humans have transformed into an ecological trap for Bonelli’s eagles in contemporary times. Presently, the populations of this species in the western Palearctic are significantly jeopardized by threats such as electrocution and habitat degradation, which stem from the extensive intensification of human activities.
The interesting thing here, and what creationists will need to ignore, is the way an environmental change altered the competitive balance allowing Bonelli's eagle to exploit the fact that, while they tolerate human habitation well, golden eagles don't, so this created a vacant niche Bonelli's could move into.Abstract
- Modern humans widely shaped present ecosystems through intentional and unintentional geographical redistribution of wildlife, both in historical and pre-historical times. However, the patterns of ancient human-mediated indirect changes in wildlife range are largely unknown, and the mechanisms behind them remain obscure. We used a multidisciplinary approach to (a) reconstruct the process of colonization of the Mediterranean Basin by a long-lived bird of prey, the Bonelli's eagle (Aquila fasciata), and (b) test the hypothesis that this colonization was unintentionally favoured by anatomically modern humans through a release of competition by dominant species, primarily golden eagles (A. chrysaetos).
- The fossil record of Bonelli's eagles in the Mediterranean Basin was restricted to the last c. 50 ky. This timing matches the period of modern human presence in Europe. Distribution modelling showed that Bonelli's eagles find more suitable conditions in interglacial periods, while glacial maxima are largely unfavourable unless in coastal refugia. In agreement with this, all Bonelli's eagle's fossils were found in coastal areas, and demographic inference from genetic data revealed a drop in the effective population size by around the last glacial maximum.
- In today's communities, we found a strongly asymmetric competitive relationship between (subordinate) Bonelli's and (dominant) golden eagles, with the former occupying far more humanized areas than the latter both at the landscape scale and the local (i.e. nesting cliff) scale. Moreover, the nesting habitat overlap analysis indicated that, in the absence of the other species, a notably higher population of Bonelli's eagle, but not of golden eagle, could be expected.
- Our findings are consistent with the human-mediated competitor release hypothesis, by which anatomically modern humans could have unintentionally favoured the large-scale colonization by Bonelli's eagles of a previously competitively hostile Mediterranean Basin. Reconstructing the role of ancient humans in shaping present ecosystems may help to understand the historical, current and future population trajectories of competing species of conservation concern under the ongoing scenario of global environmental change. It also illustrates how human-mediated apparent competition may promote large-scale redistribution and colonization of wildlife, including long-lived species.
1 INTRODUCTION
The modern human fingerprint in ecosystems through species extinctions and geographical redistribution has been pervasive since our lineage spread out of Africa (Boivin et al., 2016). Early humans contributed to precipitate the extermination of Pleistocene megafauna in several continents (Araujo et al., 2015; Barnosky et al., 2004; Dembitzer et al., 2022; Sandom et al., 2014), and we are currently driving an alarming biodiversity global crisis (Barnosky et al., 2012; Dirzo et al., 2014.1). Since the rise of agriculture and domestication, especially in historical times, there are numerous examples of human-caused reshaping of the distribution range of both domestic (Diamond, 2002; Zeder, 2008) and wild species (Davies, 2009; Lockwood et al., 2013). However, little is known about the patterns and mechanisms behind human-mediated indirect changes in wildlife demography and distribution that occurred in pre-historical and pre-domestication times (Boivin et al., 2016).
The Mediterranean Basin has undergone multiple and continued cultural exchanges (Valdiosera et al., 2018). Anatomically modern humans have been present in northern Africa since at least 160 ka (Smith et al., 2007), and they spread later into the European Mediterranean coast, with records since 56.8–51.7 ka for western Europe (Slimak et al., 2022.1). During the Pleistocene–Holocene transition, humans induced severe changes in Mediterranean landscapes, involving not only the extinction of megaherbivores (Rodríguez et al., 2004.1), but also the use of fire that created open habitats (Haws, 2012.1; Steward, 1956). Human impact on the Mediterranean Basin increased with the establishment of farming and herding societies (Naveh, 1975), which spread in Europe along an east (10.5 ka) to west (7.3 ka) wave and reached northern Africa 7 ka (Simões et al., 2023; Zeder, 2008). As a result of this ecological and socio-cultural context, human-related intentional and unintentional changes in species range have been common in the Mediterranean region in both ancient and recent times (Clavero et al., 2016.1; Gaubert et al., 2009.1; Gippoliti & Amori, 2006).
However, many past wildlife–human relationships must remain undiscovered in the Mediterranean and elsewhere—though there are signs that suggest an anthropogenic fingerprint in the present distribution of some species. This may be the case of the Bonelli's eagle (Aquila fasciata), a long-lived, large bird of prey whose presence in the Mediterranean Basin is suspected to be relatively recent. Although the status of the Bonelli's eagle during the Pleistocene in Europe has never been analysed in detail, fossils of this species in the Mediterranean Basin seem to be restricted to the period after the arrival of anatomically modern humans. In contrast, other representatives of the genus Aquila, such as golden (A. chrysaetos) and Spanish imperial eagles (A. adalberti), were present in this area well before (Sánchez-Marco, 2004.2). Also, the occurrence of the Bonelli's eagle in the Mediterranean is noteworthy from the geographical point of view, as the Mediterranean Basin represents the northwestern extreme of its current distribution range, which mainly falls into tropical and subtropical areas of southern Asia (Ferguson-Lees & Christie, 2001; IUCN, 2016.2; Appendix S1: Figure S1). Not surprisingly, this species is highly sensitive to low temperatures (Gil-Sánchez et al., 2004.3; Moreno-Rueda et al., 2009.2; Muñoz et al., 2005; Ontiveros & Pleguezuelos, 2003). The main documented competitor of Bonelli's eagle in Mediterranean regions is the golden eagle, a larger species that influences Bonelli's eagle's nest-site selection (Gil-Sánchez et al., 1996) and negatively impacts several demographic parameters (Carrete et al., 2006.1; Gil-Sánchez et al., 2004.3), including territory displacement, nest usurpation and even mortality through direct attacks (Bautista et al., 2013.1; Bosch et al., 2007.1). Both species widely segregate throughout their global distribution area, but overlapping is widespread in the Mediterranean Basin (IUCN, 2016.2; Appendix S1: Figure S1). All this raises a number of questions: Were Bonelli's eagles actually absent from the Mediterranean Basin before the arrival of humans? If so, what caused the establishment and spread of the Bonelli's eagle through a competitively unfavourable environment? Could humans have altered this competitive scenario?
In this study, we gather insights from different disciplines to test the hypothesis that the current distribution of a competitively subordinate species, the Bonelli's eagle, in the Mediterranean Basin is a product of the unintentional human-mediated release of competition by dominant species, especially the golden eagle. We followed a two-pronged approach, whereby we first describe the colonization pattern of the Mediterranean Basin by the Bonelli's eagle and then propose an ecological mechanism that could explain it. On one hand, we reconstructed the potential past geographical distribution of Bonelli's eagle and its main competitor in the Mediterranean Basin through spatial modelling, and used genetic data to trace the demographic history of the Bonelli's eagle in the Mediterranean Basin. This allowed us to explore the influence of climatic changes related to glacial ages on distribution and demographic patterns. We also revised the fossil record to estimate the time by which Bonelli's eagles established in the Mediterranean Basin. On the other hand, we disentangled the asymmetric competitive interactions between Bonelli's and golden eagles in relation to human presence, as a mechanism potentially behind the human-mediated competitive release hypothesis.
Moleón, M., Graciá, E., García, N., Gil-Sánchez, J. M., Godinho, R., Beja, P., Palma, L., Real, J., Hernández-Matías, A., Muñoz, A. R., Arrondo, E., & Sánchez-Zapata, J. A. (2024).
Wildlife following people: A multidisciplinary assessment of the ancient colonization of the Mediterranean Basin by a long-lived raptor. People and Nature, 6, 1303–1319. https://doi.org/10.1002/pan3.10642
Copyright: © 2024 The authors.
Published by John Wiley & Sons, Inc. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
Creationists who don't understand evolution will latch onto the obvious here and claim this isn't evolution - which of course no-one is claiming it is - but it neatly illustrates how subtle environmental change can bring about an extension of a species range into new territory, where a combination of the founder effect and genetic drift as well as the operation of new environmental selectors can result in allopatric speciation and increased biodiversity.
Then, of course, there is the fact that like about 99.999% of the history of life in Earth, this all happened before 'Creation Week' - some 40,000 years before it to be precise - when Homo sapiens, whom creationists think hadn't been magicked up out of dirt yet, were migrating around the northern shores of the Mediterranean and bringing about environmental changes that benefitted Bonelli's eagle.
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