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Projects to reduce emissions from deforestation and degradation (REDD) are designed to reduce carbon emissions through avoided deforestation and degradation, and in many cases, to produce additional community and biodiversity conservation co-benefits. While these co-benefits can be significant, quantifying conservation impacts has been challenging, and most projects use simple species presence to demonstrate positive biodiversity impact. Some of the same tools applied in the quantification of climate mitigation benefits have relevance and potential application to estimating co-benefits for biodiversity conservation. In western Tanzania, most chimpanzees live outside of national park boundaries, and thus face threats from human activity, including competition for suitable habitat. Through a case study of the Ntakata Mountains REDD project in western Tanzania, we demonstrate a combined application of deforestation modelling with species distribution models to assess forest conservation benefits in terms of avoided carbon emissions and improved chimpanzee habitat. The application of such tools is a novel approach that we argue permits the better design of future REDD projects for biodiversity co-benefits. This approach also enables project developers to produce the more manageable, accurate and cost-effective monitoring, reporting and verification of project impacts that are critical to verification under carbon standards.

Chimpanzees, like all great ape species, have experienced a dramatic decline in global numbers during the past decades. The degradation, fragmentation and loss of suitable habitat impede chimpanzee movements, reducing the potential for dispersal and thus population viability. In Tanzania, 90% of the 2000–3000 remaining chimpanzees are found within the Greater Mahale Ecosystem (GME), the majority of which live at low densities outside of national park boundaries. Recent genetic analyses have identified potential boundaries between the northern and southern populations of the GME. Using landscape connectivity modelling, we aimed to clarify population connectivity across this vast ecosystem (>20,000 km2) and assess change over time. We developed habitat suitability models to create an index of habitat selection by chimpanzees and mapped connectivity using circuit theory. Our results suggest that, in recent history (1973), the entire ecosystem was linked by a series of corridors showing a high likelihood of chimpanzee movement. Our analysis also reveals a reduction of connectivity by 2017 impacting the two corridors linking the northern and southern GME. When projected to 2027, areas contributing to connectivity are predicted to continue to decline, threatening all available corridors between the northern and southern GME. By modelling connectivity across time, we were able to identify key areas to focus conservation efforts to maintain population viability within the largest chimpanzee population in Tanzania.

Dispersal and establishment of new breeding populations of Sitta pusilla (Brown-headed Nuthatch) outside of its historic range in Virginia have been recorded since the 1960s. We systematically gathered published and unpublished occurrences of Brown-headed Nuthatches beyond their historic range in Virginia from 1966 to 2019 and evaluated local and landscape characteristics of sites in these areas. Brown-headed Nuthatches have expanded their distribution in Virginia into 29 counties, with breeding confirmed and/or sustained observations over more than 1 year recorded at 38 sites in 16 counties (26 sites in the Piedmont in 10 counties; 12 sites in the Ridge and Valley in 6 counties). The majority (25 of 38; 66%) of these new sites occupied by Brown-headed Nuthatches occur in semi-open recreational and residential areas, and the remaining 13 sites occur in areas broadly classified as forest. Pinus spp. (pines) are present at 37 of 38 occupied sites, most frequently P. virginiana (Virginia Pine) and P. strobus (Eastern White Pine), with an average canopy cover (all tree species) of 57% within a 250-m radius of each site. Pine-dominated forest represented a small percentage (1–24%) of land-cover types at a landscape scale (areas within a 5-km radius of occupied sites), not exceeding 4% in the Ridge and Valley region. Most colonization of these sites by Brown-headed Nuthatches in Virginia was not associated with the expansion of pine plantations, except for an apparent recent (2015–2018) association with P. taeda (Loblolly Pine) in the northern Piedmont. In the context of the current range expansion, we identify 3 management interventions (provision of nest boxes, management of Loblolly Pine plantations, restoration of P. echinata [Shortleaf Pine]) that could serve to provide suitable nesting habitat conditions for Brown-headed Nuthatches in Virginia.