Not only jackals in the cities and dolphins in the harbours: less optimism and more systems thinking is needed to understand the long-term effects of the COVID-19 lockdown

Recent evidence has shown how the global ‘Anthropause’, i.e. ‘The Great Pause’ (sensu Rutz et al. 2020) following the lockdown adopted by many countries to combat the COVID-19 coronavirus (SARS-CoV2) pandemic, has led to an immediate reduction in people mobility and, consequently, to a significant reduction in pollution due to motor-vehicle traffic (Connerton et al. 2020; Le Quéré et al. 2020; Loh et al. 2021). It has been suggested that this phenomenon could induce positive cascade effects on species, communities, ecosystems and processes (Bar 2021; Bera et al. 2021; Mandal 2020; Manenti et al. 2020). After the lockdown, an environmental-based optimism characterized the information on mass media with news stories about dolphins swimming in harbours (Trieste, Italy) and about jackals (Tel Aviv, Israel), pumas (Santiago, Chile), deer (Nara, Japan) and monkeys (New Delhi) observed in the cities (e.g. Mohite and Sarode 2020; Rutz et al. 2020; Silva-Rodríguez et al. 2021) – indeed, social media abounds with posts sharing occurrences of wild animals in urbanized areas (e.g. https://www.countryliving.com/uk/news/g32066174/ animals-deserted-towns-cities-lockdown/). This linear cause–effect relationship (i.e. lockdown = less mobility = less impact on ecosystems) was widely communicated by mass and social media to the general public, who perceived a simple and intuitive message: ‘Thanks to “Great Pause”, Nature recovers’ (Franza 2018; ‘Nurture to Nature via COVID’: Paital 2020). Certainly, one of the immediate effects of the long lockdowns and the consequent stalling of national economies is the reduction in resource consumption and human-induced impacts on ecosystems. However, the super-complexity of socio-ecological systems, as adaptive systems characterized by high uncertainty and low predictability (Maldonado et al. 2020), could start counterintuitive and non-linear medium-/longterm processes, able to generate ‘surprises’ and ‘Black Swans’ (i.e. rare and unexpected events with dramatic consequences; McDaniel, Jordan, and Fleeman 2003; Anderson et al. 2017; Platje, Harvey, and RaymanBacchus 2020; Figure 1). Just a few examples: (i) when tourist traffic to a seabird colony of common murres (Uria aalge) closed down following the COVID-19 lockdown, it led to an unexpected increase in a top predator, white-tailed eagles (Haliaeetus albicilla), resulting in the worst breeding season for this rare bird of conservation concern (Hentati-Sundber et al. 2021); (ii) in India, some rivers have benefited from reduced pollution but, unexpectedly, food-insecure peoples have turned to iconic endangered fish for food, bringing about the paradox that cleaner rivers increase the extinction risk to threatened species (Pinder et al. 2020) – and so on (see examples in Cooke et al. 2021a). With this in mind, perhaps a brainstorming exercise should be proposed among ecologists and conservation managers to examine this first, explorative 10-point list. First: in the face of a lockdown-induced reduction in people mobility, the restriction of large sections of the population to their homes led to a surge in domestic consumption (water, gas, electricity, production of household waste) when compared to pre-COVID-19 times (Ning and Wang 2020). The net balance and the resulting implications of a possible impact on species and ecosystems have not yet been investigated. Second: fear of contagion led to a heavy reduction in the use of public transport in the phases preceding and following the lockdown, with a consequent increase in private vehicle traffic (with possible consequent impacts on biodiversity, e.g. animal roadkill: Manenti et al. 2020) and a surge in consumption of fossil fuels and in pollu-