Allen H. Hurlbert

Long‐term standardized surveys are the cornerstone of our ability to measure changes in populations. Throughout North America, the North American Breeding Bird Survey (BBS) has been instrumental in documenting population changes on a broad scale. However, individual survey routes are often far apart, posing a challenge to assessing population dynamics at a fine spatial scale or to address responses to local land‐use change. Community science efforts like eBird have helped to fill this gap by expanding spatial coverage, but the lack of standardized survey effort limits its suitability for evaluating trends. To bridge this gap, we present the North Carolina Mini Breeding Bird Survey (NCMBBS), a long‐term, standardized breeding bird surveying program designed to provide high spatial resolution data for three counties in central North Carolina. The NCMBBS has been conducted annually since 1999 and has so far surveyed 208,366 individuals of 119 bird species as of 2025. The temporal extent of the NCMBBS enables analysis of long‐term population change, while the spatial coverage supports study of local drivers of change. The NCMBBS complements large‐scale programs such as the BBS by enabling multi‐scale analyses of standardized data. The data are available for reuse under the MIT License, and users should cite this data paper if they make use of the NCMBBS and acknowledge the contributions of the volunteers who conduct our surveys.

Macroevolutionary studies have shown that the shape of phylogenetic trees differs in space, time, and between taxa. It is commonly assumed that these differences in tree shape reflect variability in the underlying ecological and evolutionary processes that produced them, and mechanistic eco-evolutionary models are increasingly used to explore this link. A concern in this context is whether conclusions drawn from such mechanistic models are robust to idiosyncrasies in how eco-evolutionary processes are formalized in the models. Here, we use eight mechanistic macroevolutionary models to study how 52 metrics of phylogenetic tree shape respond to variation in the strength of five fundamental processes: competition, dispersal, environmental filtering, niche conservatism, and speciation. We find that models agree on how some tree metrics respond to changes in these processes, in particular dispersal and speciation. However, no tree metric uniquely correlated with a single process, suggesting that single tree metrics have limited utility as shortcuts for inferring the underlying eco-evolutionary processes. Moreover, although it was possible to infer the underlying processes if the data-generating model was known, inference was not consistent across the different models. We conclude that the relationship between phylogenetic patterns and eco-evolutionary processes in macroevolutionary analysis is likely sensitive to the structural and mechanistic details of how a given process is implemented within models.

Aim: To determine how species richness gradients—commonly considered universal—vary across the phylogenetic hierarchy of birds and mammals, and to uncover how clade age and size predetermine the gradients. Location: Global. Time Period: Last 120 million years. Taxa Studied: Birds and mammals (~15,000 species). Methods: We used large‐scale phylogenies of birds and mammals and captured the species richness gradient for each of their monophyletic clades. Gradient strength was quantified with respect to latitude, environmental productivity and temperature using multiple measures (raw slopes, log transformation, log–log transformation, and correlations). To distinguish statistical from biological effects, we compared the observed gradients to those generated by null models that randomly reassigned species to clades while preserving the phylogeny and species distributions. Results: Species richness gradients show considerable variation. Small and young clades exhibited inconsistent gradients—including reverse or flat gradients—while older and larger clades converged on steep, consistent gradients. Even moderately large clades (~500 species) commonly displayed reverse gradients. Null models replicated this trend but only partially, implying that biological effects also drive gradient variation. These phylogenetic trends were sensitive to the choice of gradient measure: raw slopes frequently inflated the strength of this trend and the apparent differences among clades, while log and log–log transformations revealed only moderate trends. Main Conclusions: Species richness gradients are not universal, nor are they phylogenetic scale‐invariant. Instead, they follow systematic trends across the phylogenetic hierarchy. Young, small clades often bear signatures of their region of origin and historical dispersal, whereas older, larger clades converge on similar gradients. Recognising the variation and the phylogenetic trends within it elucidates the formation of biodiversity patterns. We offer guidelines for choosing gradient measures, arguing that multiple metrics, combined with careful use of null models, are necessary for a nuanced understanding of how, and why, global biodiversity patterns diverge from the presumed universal gradients.

Alien plants have generally been shown to support reduced arthropod abundance, biomass, and diversity, but inferences have typically come from studies limited in taxonomic and geographic scope. Here, we make use of data from a unique citizen science project, Caterpillars Count! , that consists of nearly 70,000 standardized surveys of woody plant branches across eastern North America on over 100 plant species. From these data we find that caterpillar (i.e. larval Lepidoptera) occurrence was nearly 4 times higher, beetle (order Coleoptera) occurrence was 50% higher, and spider (order Araneae) occurrence was 17% higher on native versus alien plants. The occurrence of hoppers and allies (suborder Auchenorrhyncha) was slightly higher on alien plants, while there was little difference in occurrence on native versus alien plants for ants (family Formicidae) or true bugs (suborder Heteroptera). Species richness of caterpillars, spiders, and beetles was also higher on average on native versus alien plants. The increased occurrence of caterpillars on native plants was consistent across plant families, whereas differences between native and alien plants for the other arthropod groups were highly variable across plant families. Caterpillar occurrence varied widely both within and between plant families, suggesting the importance of other plant species characteristics beyond native versus alien origin. Finally, we show that caterpillar occurrence appears to increase with latitude on alien plants at a faster rate than it does on native plants, but that this difference can be attributed to shifts in the identity and composition of plant species across the latitudinal gradient within our dataset. These findings have implications for how the increased spread of alien plants may impact ecosystems and food webs, and for land managers seeking to mitigate those changes.

Motivation: Here, we make available a second version of the BioTIME database, which compiles records of abundance estimates for species in sample events of ecological assemblages through time. The updated version expands version 1.0 of the database by doubling the number of studies and includes substantial additional curation to the taxonomic accuracy of the records, as well as the metadata. Moreover, we now provide an R package (BioTIMEr) to facilitate use of the database.Main Types of Variables Included: The database is composed of one main data table containing the abundance records and 11 metadata tables. The data are organised in a hierarchy of scales where 11,989,233 records are nested in 1,603,067 sample events, from 553,253 sampling locations, which are nested in 708 studies. A study is defined as a sampling methodology applied to an assemblage for a minimum of 2 years.Spatial Location and Grain: Sampling locations in BioTIME are distributed across the planet, including marine, terrestrial and freshwater realms. Spatial grain size and extent vary across studies depending on sampling methodology. We recommend gridding of sampling locations into areas of consistent size.Time Period and Grain: The earliest time series in BioTIME start in 1874, and the most recent records are from 2023. Temporal grain and duration vary across studies. We recommend doing sample‐level rarefaction to ensure consistent sampling effort through time before calculating any diversity metric.Major Taxa and Level of Measurement: The database includes any eukaryotic taxa, with a combined total of 56,400 taxa.Software Format: csv and. SQL.

Climate change has been repeatedly linked to phenological shifts in many taxa, but the factors that drive variation in phenological sensitivity remain unclear. For example, relatively little is known about phenological responses in areas that have not exhibited a consistent warming trend, making it difficult to project phenological responses in response to future climate scenarios for these regions. We used an extensive community science dataset to examine changes in the adult flight onset dates of 38 butterfly species with interannual variation in spring temperatures in the Piedmont region of North Carolina, a region that did not experience a significant overall warming trend in the second half of the 20th century. We also explored whether voltinism, overwintering stage, and mean adult flight onset dates explain interspecific variation in phenological sensitivity to spring temperature. We found that 12 out of 38 species exhibited a significant advance in adult flight onset dates with higher spring temperatures. In comparison, none of the 38 species exhibited a significant advance with year. There was a significant interaction between mean onset flight date and voltinism, such that late-emerging, multivoltine species tended to be the most sensitive to spring temperature changes. We did not observe a significant correlation between phenological sensitivity and the overwintering stage. These results suggest that butterfly arrival dates may shift as temperatures are projected to rise in the southeastern United States, with late-emerging, multivoltine species potentially exhibiting the greatest shifts in adult flight onset dates.

We assessed the relative importance of environmental filtering and dispersal limitation in structuring foliage- and ground-dwelling arthropod communities in central North Carolina. We hypothesized that differences in both local environment and dispersal distance between sites would predict differences in community composition, but that dispersal distance would be more important for ground arthropods than for foliage arthropods. We used variance partitioning to quantify the relative explanatory power of differences in the local environment and dispersal distance between sampling plots. For foliage arthropods, the full set of predictors explained 37–39% of the variance in community dissimilarity, while the full set of predictors explained 42–56% of the variance for ground arthropods. Environmental predictors alone consistently explained more variance in community dissimilarity than geographic predictors alone for ground arthropods, but the variance explained by each predictor set alone varied for foliage arthropods depending on the metric of community dissimilarity. Examining communities of multiple arthropod groups across the same spatial gradient highlights the scale-dependence of these processes and illustrates how variation in the environment can alter the relative abundance of specialist and generalist taxa.

We assessed the relative importance of environmental filtering and dispersal limitation in structuring foliage- and ground-dwelling arthropod communities in central North Carolina. We hypothesized that both the local environment and the dispersal distance between sites would predict community composition, but that dispersal distance would be more important for ground arthropods than for foliage arthropods. In both groups, variation in habitat characteristics was important in structuring communities, and the role of dispersal in structuring communities was much greater after accounting for variation in landscape connectivity. Our results demonstrate the importance of both dispersal limitation and environmental filtering in shaping community composition and emphasize the importance of variation in the landscape for modeling these forces. Examining communities of multiple arthropod groups across the same spatial gradient highlights the scale-dependence of these processes and illustrates how variation in the environment can alter the relative abundance of specialist and generalist taxa.

Changes in phenology in response to ongoing climate change have been observed in numerous taxa around the world. Differing rates of phenological shifts across trophic levels have led to concerns that ecological interactions may become increasingly decoupled in time, with potential negative consequences for populations. Despite widespread evidence of phenological change and a broad body of supporting theory, large-scale multitaxa evidence for demographic consequences of phenological asynchrony remains elusive. Using data from a continental-scale bird-banding program, we assess the impact of phenological dynamics on avian breeding productivity in 41 species of migratory and resident North American birds breeding in and around forested areas. We find strong evidence for a phenological optimum where breeding productivity decreases in years with both particularly early or late phenology and when breeding occurs early or late relative to local vegetation phenology. Moreover, we demonstrate that landbird breeding phenology did not keep pace with shifts in the timing of vegetation green-up over a recent 18-y period, even though avian breeding phenology has tracked green-up with greater sensitivity than arrival for migratory species. Species whose breeding phenology more closely tracked green-up tend to migrate shorter distances (or are resident over the entire year) and breed earlier in the season. These results showcase the broadest-scale evidence yet of the demographic impacts of phenological change. Future climate change–associated phenological shifts will likely result in a decrease in breeding productivity for most species, given that bird breeding phenology is failing to keep pace with climate change.