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Avian population sizes fluctuate and change over vast spatial scales, but the mechanistic underpinnings remain poorly understood. A key question is whether spatial and annual variation in avian population dynamics is driven primarily by variation in breeding season recruitment or by variation in overwinter survival. We present a method using large‐scale volunteer‐collected data from project eBird to develop species‐specific indices of net population change as proxies for survival and recruitment, based on twice‐annual, rangewide snapshots of relative abundance in spring and fall. We demonstrate the use of these indices by examining spatially explicit annual variation in survival and recruitment in two well‐surveyed nonmigratory North American species, Carolina wren Thryothorus ludovicianus and northern cardinal Cardinalis cardinalis. We show that, while interannual variation in both survival and recruitment is slight for northern cardinal, eBird abundance data reveal strong and geographically coherent signals of interannual variation in the overwinter survival of Carolina wren. As predicted, variation in wintertime survival dominates overall interannual population fluctuations of wrens and is correlated with winter temperature and snowfall in the northeastern United States, but not the southern United States. This study demonstrates the potential of participatory science (also known as citizen science) datasets like eBird for inferring variation in demographic rates and introduces a new complementary approach towards illuminating the macrodemography of North American birds at comprehensive continental extents.

Information about seed dispersal effectiveness (SDE) for plant species of conservation concern is rarely available to inform management strategies and actions. For Lindera subcoriacea (bog spicebush, Lauraceae), a rare endemic dioecious shrub of the southeastern United States, we examined the influence of two intrinsic and five extrinsic drivers on the number and proportion of seeds either dispersed, or predated pre- and post-dispersal. The number of seeds dispersed characterizes the quantitative component of SDE, while pre- and post-dispersal seed predation can affect the qualitative component of SDE. Using fruit counts, seed traps, and seed removal depots over multiple years, we estimated that approximately 28% of L . subcoriacea seeds are lost to pre-dispersal predation, 69% of seeds are dispersed, 3% of seeds fail to disperse, and 65% of dispersed seeds are predated post-dispersal. We observed substantial variation in these three processes among individuals. We also found that both intrinsic (plant height, crop size) and extrinsic (understory cover, time since last fire, conspecific fruiting neighborhood, substrate) drivers differentially influenced the three processes. We identified four generalist, seasonally frugivorous, avian visitors at fruiting individuals that likely act as variably effective dispersers, while the Northern Cardinal ( Cardinalis cardinalis L.) is a seed predator. Rodent granivores were important pre- and post-dispersal seed predators. The magnitude of our pre-dispersal and post-dispersal seed predation estimates suggest that, given the low fecundity of L . subcoriacea , conservation strategies should emphasize facilitating dispersal and reducing the effects of seed predation.

The distributions of animal populations change and evolve through time. Migratory species exploit different habitats at different times of the year. Biotic and abiotic features that determine where a species lives vary due to natural and anthropogenic factors. This spatiotemporal variation needs to be accounted for in any modeling of species' distributions. In this paper we introduce a semiparametric model that provides a flexible framework for analyzing dynamic patterns of species occurrence and abundance from broad-scale survey data. The spatiotemporal exploratory model (STEM) adds essential spatiotemporal structure to existing techniques for developing species distribution models through a simple parametric structure without requiring a detailed understanding of the underlying dynamic processes. STEMs use a multi-scale strategy to differentiate between local and global-scale spatiotemporal structure. A user-specified species distribution model accounts for spatial and temporal patterning at the local level. These local patterns are then allowed to \"scale up\" via ensemble averaging to larger scales. This makes STEMs especially well suited for exploring distributional dynamics arising from a variety of processes. Using data from eBird, an online citizen science bird-monitoring project, we demonstrate that monthly changes in distribution of a migratory species, the Tree Swallow ( Tachycineta bicolor ), can be more accurately described with a STEM than a conventional bagged decision tree model in which spatiotemporal structure has not been imposed. We also demonstrate that there is no loss of model predictive power when a STEM is used to describe a spatiotemporal distribution with very little spatiotemporal variation; the distribution of a nonmigratory species, the Northern Cardinal ( Cardinalis cardinalis ).

The invasive Jorō spider ( L. Koch: Araneae: Nephilidae), which was found to be established in Georgia in 2014, has become abundant and spread to many other states. Almost nothing is known about what predates the Jorō spider in its invasive range. A previous paper reported a Northern Cardinal ( L. [Passeriformes: Cardinalidae]) perching on the web of a Jorō spider and lunging towards it, in what was interpreted to be a predation attempt. This note reports attacks by two Northern Cardinals (referred to hereafter as Cardinal) on Jorō spiders in Atlanta, Georgia. The first attack was observed when a male Cardinal continuously pecked at the top of a caged Jorō, just above the large female spider. Shortly after this attack a large living female Jorō spider was tethered by a thread around the pedicel and hung above and near to the caged Jorō that was attacked. After nearly an hour had passed, a female Cardinal flew in and grabbed the Jorō in its beak and tried to fly away with the spider. The Cardinal quickly returned and attacked the spider two more times but was unable to fly away with it because the tether held the spider in place. The spider was killed but not dismembered. Cardinals may be responsible for the destroyed and empty Jorō webs that are commonly seen. Although Cardinals are thought by many people as seed feeders, research has shown that they are among the most insectivorous of common birds.

Much attention has been paid to the impacts of plastics and other debris on marine organisms, but the effects of plastic on terrestrial organisms have been largely ignored. Detrimental effects of terrestrial plastic could be most pronounced in intensively human-modified landscapes (e.g., urban and agricultural areas), which are a source of much anthropogenic debris. Here, we examine the occurrence, types, landscape associations, and consequences of anthropogenic nest material in the American crow (Corvus brachyrhynchos), a North American species that breeds in both urban and agricultural landscapes. We monitored 195 nestlings in 106 nests across an urban and agricultural gradient in the Sacramento Valley, California, USA. We found that 85.2% of crow nests contained anthropogenic material, and 11 of 195 nestlings (5.6%) were entangled in their nests. The length of the material was greater in nests in agricultural territories than in urban territories, and the odds of entanglement increased 7.55 times for each meter of anthropogenic material in the nest. Fledging success was significantly lower for entangled than for unentangled nestlings. In all environments, particularly urban, agricultural, and marine, careful disposal of potential hazards (string, packing and hay bale twine, balloon ribbon, wire, fishing line) could reduce the occurrence of entanglement of nestling birds.

In many agroecosystems, brown marmorated stink bugs (Halyomorpha halys) (Hemiptera: Pentatomidae) are polyphagous pests that cause significant economic losses to numerous crops every year. Insectivorous birds may provide a means of sustainable predation of invasive pests, such as H. halys. In forest margins surrounding peach, pecan, and interplanted peach–pecan orchards, we monitored H. halys populations with pheromone-baited traps, mist-netted birds, and collected avian fecal samples for molecular gut content analysis. We screened 257 fecal samples from 19 bird species for the presence of H. halys DNA to determine whether birds provide the biological control of this pest. Overall, we found evidence that four birds from three species consumed H. halys, including Northern cardinal (Cardinalis cardinalisis), Tufted titmouse (Baeolophus bicolor), and Carolina wren (Thryothorus ludovicianus). Halyomorpha halys captured in traps increased over time but did not vary by orchard type. Although incidence of predation was low, this may be an underestimate as a result of our current avian fecal sampling methodology. Because birds are members of the broader food web, future studies are needed to understand avian ecosystem services, especially in terms of pest control, including H. halys and other pest species.

Tool use has been observed in over two dozen families of birds, though few wild birds outside of corvids have been observed using tools in acts of agonism; we present additional accounts of this behavior in both corvids and cardinals. On 9 June 2023 we observed and video-recorded a male Northern Cardinal (Cardinalis cardinalis) repeatedly pick up a pebble and strike the side-view mirror of a vehicle in a parking lot at Great Smoky Mountains National Park, Tennessee, USA. We searched YouTube and found several videos of wild birds attacking their reflection in a mirror or window. None appeared to use a pebble or other weapon to attack, but a White-winged Chough (Corcorax melanorhamphos) used a pebble to strike the windshield of a vehicle and a Common Raven (Corvus corvax) dropped a stone on a domestic dog. We interpret our observation as indicating tool use by a Northern Cardinal, one of the few accounts outside of corvids of a bird using a tool in an act of agonism. We also show that online videos can help researchers detect novel behaviors, including tool use and tooling, in wild birds. Se ha observado el uso de herramientas en más de dos docenas de familias de aves, aunque pocas aves silvestres fuera de la familia de los córvidos han sido observadas usando herramientas en actos de agonismo; presentamos reportes adicionales de este comportamiento tanto en córvidos como en cardenales. El 9 de junio del 2023 observamos y video-grabamos un cardenal Cardinalis cardinalis macho que repetidamente levantó un guijarro y golpeó el espejo lateral de un vehículo en un estacionamiento en Great Smoky Mountains National Park, Tennessee, Estados Unidos. Hicimos una búsqueda en YouTube y encontramos varios videos de aves silvestres atacando su propio reflejo en espejos o en ventanas. Ninguna parecía usar guijarros para atacar pero un corvino Corcorax melanorhamphos usó un guijarro para golpear el parabrisas de un vehículo y un cuervo Corvus corax dejó caer una piedra sobre un perro doméstico. Interpretamos nuestra observación como una indicación de uso de herramienta por un cardenal, uno de los pocos reportes fuera de los córvidos de uso de herramienta como acto de agonismo. También mostramos que los videos en línea pueden ayudar a los investigadores a detectar comportamientos novedosos, incluyendo el uso de herramientas y de herramientas en aves silvestres. Palabras clave: agonismo, comportamiento, espejo, uso de herramientas aviares, vídeos en línea, YouTube

Background Earth history events such as climate change are believed to have played a major role in shaping patterns of genetic structure and diversity in species. However, there is a lag between the time of historical events and the collection of present-day samples that are used to infer contemporary population structure. During this lag phase contemporary processes such as dispersal or non-random mating can erase or reinforce population differences generated by historical events. In this study we evaluate the role of both historical and contemporary processes on the phylogeography of a widespread North American songbird, the Northern Cardinal, Cardinalis cardinalis . Results Phylogenetic analysis revealed deep mtDNA structure with six lineages across the species' range. Ecological niche models supported the same geographic breaks revealed by the mtDNA. A paleoecological niche model for the Last Glacial Maximum indicated that cardinals underwent a dramatic range reduction in eastern North America, whereas their ranges were more stable in México. In eastern North America cardinals expanded out of glacial refugia, but we found no signature of decreased genetic diversity in areas colonized after the Last Glacial Maximum. Present-day demographic data suggested that population growth across the expansion cline is positively correlated with latitude. We propose that there was no loss of genetic diversity in areas colonized after the Last Glacial Maximum because recent high-levels of gene flow across the region have homogenized genetic diversity in eastern North America. Conclusion We show that both deep historical events as well as demographic processes that occurred following these events are critical in shaping genetic pattern and diversity in C. cardinalis . The general implication of our results is that patterns of genetic diversity are best understood when information on species history, ecology, and demography are considered simultaneously.

Wildlife faces many challenges living alongside humans, but certain species can overcome these obstacles and succeed even in urban areas. Boldness and neophobia are 2 potential aspects of animal personality that could affect urban adaptation and, if correlated, may form a behavioral syndrome. If urban individuals are bolder and less neophobic than rural individuals, they may be able to exploit anthropogenic landscapes more fully. We tested this idea by conducting flight initiation distance and novel object experiments with 10 urban and 10 rural Northern Cardinals (Cardinalis cardinalis). Urban birds had shorter flight initiation distances and foraged near novel objects more readily than rural birds, and both behaviors were highly repeatable within individuals, suggestive of personality. We found a positive correlation wherein bolder individuals were also less neophobic, but only in the rural population. Thus, the urban environment may impose selective pressures that result in population-level differences in these 2 behaviors, while also decoupling them such that urban individuals can fine tune their behaviors in response to novel conditions. In contrast, the existence of a behavioral syndrome in rural birds may be an adaptive response to a more consistent environment. In total, these results help explain how Northern Cardinals can modify their behaviors, either plastically or via genetic evolution, to thrive in urban areas. La vida silvestre enfrenta muchos retos al coexistir con humanos, pero ciertas especies pueden superar esos obstáculos y tener éxito aún en áreas urbanas. Atrevimiento y neofobia son 2 aspectos potenciales de personalidad animal que pueden afectar la adaptación urbana y, si están correlacionadas, pueden formar un síndrome de comportamiento. Si los individuos urbanos son más atrevidos y menos neofóbicos que los individuos rurales, pueden ser capaces de aprovechar los paisajes antropogénicos completamente. Probamos la idea haciendo experimentos de distancia de vuelo de iniciación y y de objetos nuevos con 10 cardenales Cardinalis cardinalis urbanos y 10 rurales. Las aves urbanas tenían distancias más cortas de vuelo inicial y forrajeaban objetos nuevos cercanos más rápidamente que las aves rurales, y ambos comportamientos eran altamente repetibles en un individuo, lo que sugiere personalidad. Encontramos una correlación positiva en la que individuos más audaces eran menos neofóbicos, pero solo en poblaciones rurales. Por lo tanto, el ambiente urbano puede imponer presiones selectivas que resulten en diferencias poblacionales en estos dos comportamientos, a la vez que se desacoplan en medios urbanos de manera que los individuos urbanos pueden tener un ajuste fino de estos comportamientos en respuesta a las condiciones nuevas. En contraste, la existencia de un síndrome de comportamiento en aves rurales puede ser una respuesta adaptativa a un ambiente más consistente. En total, estos resultados ayudan a explicar cómo los cardenales pueden modificar su comportamiento, ya sea de manera plástica o por evolución genética, para prosperar en áreas urbanas. Palabras clave: adaptación urbana, distancia de vuelo de iniciación, ecología urbana, personalidad, síndrome de comportamiento.

Eastern equine encephalitis virus (EEEV) is the most pathogenic arbovirus endemic to the United States. Studies have demonstrated Florida's role as a regional reservoir for the virus and its ability to support year-round transmission. Previous research has developed risk index models for mapping locations most at risk for EEEV transmission. We compared vector abundance, vector feeding behavior, potential host species, and fauna presence at high versus low–moderate risk sites during the winter and spring. Predicted high-risk sites had a significantly greater abundance of mosquitoes overall, including Culiseta melanura (Coquillett) (Diptera: Culicidae), the primary enzootic vector of EEEV. Twenty host species were identified from Cs. melanura bloodmeals, with the majority taken from avian species. Culiseta melanura largely fed upon the Northern Cardinal (Cardinalis cardinalis (Passeriformes: Cardinalidae)), which accounted for 20–24.4% of the bloodmeals obtained from this species in years 1 and 2, respectively. One EEEV-positive mosquito pool (Cs. melanura) and nine EEEV seropositive sentinel chickens were confirmed during winter-spring collections from high-risk sites; no seropositive chickens nor mosquito pools were found at the low–moderate risk sites. These results suggest that high-risk sites for EEEV activity are characterized by habitats that support populations of Cs. melanura and which may also provide ample opportunities to feed upon Northern Cardinals. The overall low level of mosquito populations during the winter also suggests that control of Cs. melanura populations in winter at high-risk sites may prove effective in reducing EEEV transmission during the peak summer season.