Monica Louise Bond

The Klamath-Siskiyou Ecoregion (KSE) of southwest Oregon–northern California, USA, has globally exceptional biodiversity but is experiencing mounting pressures from climate change and land uses. We conducted an ecoregional conservation assessment of the KSE and the Siskiyou Crest subregion (SCS), a proposed climate refugium within the KSE. We integrated protected area priorities based on established conservation targets with climate change planning and fire risk reduction for communities. Both areas contained very low levels (1 km from nearest structures, far removed from effective community fire protection in both locales. The relatively higher-elevation SCS is projected to maintain refugia properties (cooler, wetter) for longer periods than the KSE; however, that function may dissipate toward the end of the century and under a higher emissions scenario. We recommend increased protections of potential refugia combined with fire risk reduction of the built environment to more effectively maintain unique biota and prepare communities for increased likelihood of wildfire spillover events.

The Klamath-Siskiyou Ecoregion (KSE) of southwest Oregon-northern California, USA has globally exceptional biodiversity but is experiencing mounting pressures from climate change and land uses. We conducted an ecoregional conservation assessment of the KSE and the Siskiyou Crest subregion (SCS), a proposed climate refugium within the KSE, to integrate protected area priorities with climate change planning and fire risk reduction for communities. Both areas contained very low levels (1-km from nearest structures, far removed from effective community fire protection in both locales. The relatively higher-elevation SCS is projected to maintain refugia properties (cooler, wetter) for longer periods than the KSE; however, that function may dissipate toward the end of the century and under a higher emissions scenario. Stepped up protections especially of potential refugia combined with fire risk reduction of the built environment are urgently needed to prevent unprecedented losses.

Phenotype‐dependent demography may result from heterogeneous selection pressures, which can be altered by temperature anomalies. Understanding which phenotypes are best adapted to different temperatures could clarify how populations may adapt to climatic changes and guide effective conservation measures. Animal markings are heritable phenotypic traits that show variation within populations, which suggest they may be adaptive. Variation in marking shape and size may influence thermoregulation and lead to differing individual responses to temperature anomalies. Therefore, markings may affect survival in variable and changing environments and be important for adapting to climate change. Using resighting data from 810 wild giraffes over 8 years, we estimated viability selection on spot patterns and whether it was affected by temperature anomalies. Calves with smaller lobate and adult males with smaller lobate or larger polygonal spots survived better. Additionally, calves and adult males with larger (vs. smaller) spots that experienced anomalously low (vs. high) temperatures survived better. Spot patterns had a smaller effect on adult females, with individuals of all spot types having lower survival in anomalously high temperatures. Synthesis and applications . Spot patterns influenced giraffe survival and their effects were altered by temperature anomalies. In calves, spot size may help with thermoregulation while spot shape may conceal them from predators. In adults, sex‐specific selection pressures suggest sex differences in heat tolerance and trade‐off with different functions. Conservation management maintaining variation in spot patterns by facilitating genetic exchange (e.g. through habitat connectivity) may help giraffes to adapt to climate change. Markings may have fitness consequences in other mammalian species and be important for population adaptation.

Responses of natural populations to climate change are driven by how multiple climatic and biotic factors affect survival and reproduction, and ultimately shape population dynamics. Yet, despite substantial progress in synthesizing the sensitivity of populations to climatic variation, comparative studies still overlook such complex interactions among drivers that generate variation in population-level metrics. Here, we use a common framework to synthesize how the joint effects of climate and biotic drivers on different vital rates impact population change, using unique long-term data from 41 species, ranging from trees to primates. We show that simultaneous effects of multiple climatic drivers exacerbate population responses to climate change, especially for fast-lived species. However, accounting for density feedbacks under climate variation buffers the effects of climate change on population dynamics. In all species considered in our analyses, such interactions between climate and density had starkly different effects depending on the age, size, or life-cycle stage of individuals, regardless of the life history of species. Our work provides the first general framework to assess how covarying effects of climate and density across a wide range of population models can impact populations of plants and animals under climate change.

Survival, reproduction, and movement are the key demographic parameters that drive population dynamics. Factors affecting these demographic parameters in large, long‐lived, extinction‐threatened mammals are diverse and may differentially affect subpopulations in disparate parts of an ecosystem. We conducted annual photographic surveys to uniquely identify 1,520 giraffes at 4 subpopulations around the Serengeti Ecosystem in Tanzania to estimate demographic parameters of age‐ and sex‐specific survival probabilities, reproduction, population densities, group sizes, and long‐distance movements. In the Seronera (central) subpopulation, we combined 15 years of data from 3 independent survey schemes, developed a Bayesian hidden Markov model to estimate demographic parameters, and conducted a retrospective population analysis to elucidate the demographic drivers of temporal changes in population growth rate. We collected data over 4–5 years for 3 other subpopulations, and used frequentist methods to estimate demographic parameters. We compared our results with historical estimates from the 1970s and 2000s to examine long‐term population trends and demographic drivers. We found significant differences in adult and subadult survival probabilities among subpopulations, with lower adult survival associated with declining subpopulations. Retrospective population analysis for the Seronera subpopulation reiterated that adult survival is a critical demographic driver of population dynamics for giraffes. The 2 subpopulations adjacent to the protected area boundary declined over 48 years, whereas the Seronera subpopulation stabilized since 2008. Only one individual moved between subpopulations, providing evidence for subpopulation insularity and potential genetic structuring of the overall population. These factors underscore the need for subpopulation‐specific conservation strategies aimed at raising adult survival within the western and northeastern parts of the Serengeti Ecosystem. Community‐based conservation efforts adjacent to protected areas have been effective in raising adult survival and density elsewhere. Our findings highlight the importance of understanding subpopulation dynamics and their demographic drivers for evidence‐based conservation and management to recover endangered giraffe populations.

Giraffes exhibit a large sexual dimorphism in body size. Whether sexual dimorphisms also exist in body proportions of the axial and appendicular skeleton has been debated, particularly regarding the giraffe’s iconic long neck. We examined the anatomical proportions of the neck, forelegs, hindlegs, and body trunk of the Masai giraffe (G. tippelskirchi) in captive and wild populations. We found that female Masai giraffes have proportionally longer necks relative to their forelegs than males in contradiction to the original necks-for-sex hypothesis that proposed that the evolution of the giraffe’s long neck was driven by male-male competition. However, male neck width and apparent mass are proportionally larger than females’, supporting a modification of the necks-for-sex hypothesis. Moreover, male foreleg length is proportionally longer whereas female trunk length is proportionally longer. These sexual dimorphisms were found in both captive and wild Masai giraffes. We speculate that the initial evolution of the giraffe’s long neck and legs was driven by interspecific competition and the maternal nutritional demands of gestation and lactation through natural selection to gain a competitive advantage in browsing, and then later the neck mass was further increased as a consequence of male-male competition and sexual selection. Differences in the proportions of major body components define sex phenotypes, but several giraffes display opposite-sex phenotypes with a significantly higher level of discordancy seen in captive males. We speculate that body proportion sexual dimorphisms are maintained in the wild by natural and/or sexual selection, but in captivity selection is relaxed resulting in a higher occurrence of discordances in sexual phenotypes.

Megaherbivores play “outsized” roles in ecosystem functioning but are vulnerable to human impacts such as overhunting, land‐use changes, and climate extremes. However, such impacts—and combinations of these impacts—on population dynamics are rarely examined using empirical data. To guide effective conservation actions under increasing global‐change pressures, we developed a socially structured individual‐based model (IBM) using long‐term demographic data from female giraffes (Giraffa camelopardalis) in a human‐influenced landscape in northern Tanzania, the Tarangire Ecosystem. This unfenced system includes savanna habitats with a wide gradient of anthropogenic pressures, from national parks, a wildlife ranch and community conservation areas, to unprotected village lands. We then simulated and projected over 50 years how realistic environmental and land‐use management changes might affect this metapopulation of female giraffes. Scenarios included: (1) anthropogenic land‐use changes including roads and agricultural/urban expansion; (2) reduction or improvement in wildlife law enforcement measures; (3) changes in populations of natural predators and migratory alternative prey; and (4) increases in rainfall as predicted for East Africa. The factor causing the greatest risk of rapid declines in female giraffe abundance in our simulations was a reduction in law enforcement leading to more poaching. Other threats decreased abundances of giraffes, but improving law enforcement in both of the study area's protected areas mitigated these impacts: a 0.01 increase in giraffe survival probability from improved law enforcement mitigated a 25% rise in heavy rainfall events by increasing abundance 19%, and mitigated the expansion of towns and blockage of dispersal movements by increasing abundance 22%. Our IBM enabled us to further quantify fine‐scale abundance changes among female giraffe social communities, revealing potential source–sink interactions within the metapopulation. This flexible methodology can be adapted to test additional ecological questions in this landscape, or to model populations of giraffes or other species in different ecosystems.

With the rapid pace of global warming, there is an urgent need to understand survival responses to climate, particularly for large mammals that are already experiencing population declines associated with anthropogenic pressures such as poaching and habitat loss. We tested hypotheses about the interactive effects of local climatic anomalies (variations around a long-term mean) and proximity to edge of protected area boundaries on seasonal adult and juvenile survival in a population of 2,385 individually identified giraffes monitored over 8 years in the Tarangire Ecosystem of northern Tanzania. Temperature anomalies were positively correlated with seasonal survival of adult giraffes, suggesting these megaherbivores are adapted to hot conditions. Higher seasonal rainfall anomalies were negatively correlated with both juvenile and adult survival, and greater vegetation greenness was associated with lower adult survival. During seasons of anomalously high rainfall and vegetation greenness, higher parasite and disease abundance, poorer-quality nutrition in forage, and higher predation risk may all play a role in lowering giraffe survival. Furthermore, climate-associated reduction in survival was most pronounced during the short rainy season for adult giraffes living closer to the edge of protected areas, indicating that the influence of climate anomalies may be exacerbated by anthropogenic edge effects such as poaching or livestock keeping. Precipitation in East Africa is projected to increase substantially, with a greater proportion of rain falling during heavy events in the short rainy season, which may threaten persistence of giraffes in one of Earth’s most important landscapes for large mammals.