Songbird Species Research Articles

Springing forward: Migrating songbirds catch up with the start of spring in North America.

In temperate regions, the annual pattern of spring onset can be envisioned as a 'green wave' of emerging vegetation that moves across continents from low to high latitudes, signifying increasing food availability for consumers. Many herbivorous migrants 'surf' such resource waves, timing their movements to exploit peak vegetation resources in early spring. Although less well studied at the individual level, secondary consumers such as insectivorous songbirds can track vegetation phenology during migration as well. We hypothesized that four species of ground-foraging songbirds in eastern North America-two warblers and two thrushes-time their spring migrations to coincide with later phases of vegetation phenology, corresponding to increased arthropod prey, and predicted they would match their migration rate to the green wave but trail behind it rather than surfing its leading edge. We further hypothesized that the rate at which spring onset progresses across the continent influences bird migration rates, such that individuals adjust migration timing within North America to phenological conditions they experience en route. To test our hypotheses, we used a continent-wide automated radio telemetry network to track individual songbirds on spring migration between the U.S. Gulf Coast region and northern locations closer to their breeding grounds. We measured vegetation phenology using two metrics of spring onset, the spring index first leaf date and the normalized difference vegetation index (NDVI), then calculated the rate and timing of spring onset relative to bird detections. All individuals arrived in the southeastern United States well after local spring onset. Counter to our expectations, we found that songbirds exhibited a 'catching up' pattern: Individuals migrated faster than the green wave of spring onset, effectively closing in on the start of spring as they approached breeding areas. While surfing of resource waves is a well-documented migration strategy for herbivorous waterfowl and ungulates, individual songbirds in our study migrated faster than the green wave and increasingly caught up to its leading edge en route. Consequently, songbirds experience a range of vegetation phenophases while migrating through North America, suggesting flexibility in their capacity to exploit variable resources in spring.

Genomic divergence and introgression between cryptic species of a widespread North American songbird.

Analysis of genomic variation among related populations can sometimes reveal distinct species that were previously undescribed due to similar morphological appearances, and close examination of such cases can provide much insight regarding speciation. Genomic data can also reveal the role of reticulate evolution in differentiation and speciation. White-breasted nuthatches (Sitta carolinensis) are widely distributed North American songbirds that are currently classified as a single species but have been suspected to represent a case of cryptic speciation. Previous genetic analyses suggested four divergent groups, but it was unclear whether these represented multiple reproductively isolated species. Using extensive genomic sampling of over 350 white-breasted nuthatches from across North America and a new chromosome-level reference genome, we asked if white-breasted nuthatches are comprised of multiple species and whether introgression has occurred between divergent populations. Genomic variation of over 300,000 loci revealed four highly differentiated populations (Pacific, n = 45; Eastern, n = 23; Rocky Mountains North, n = 138; and Rocky Mountains South, n = 150) with geographic ranges that are adjacent. We observed a moderate degree of admixture between Rocky Mountain populations but only a small number of hybrids between the Rockies and the Eastern population. The rarity of hybrids together with high levels of differentiation between populations is supportive of populations having some level of reproductive isolation. Between populations, we show evidence for introgression from a divergent ghost lineage of white-breasted nuthatches into the Rocky Mountains South population, which is otherwise closely related to Rocky Mountains North. We conclude that white-breasted nuthatches are best considered at least three species and that ghost lineage introgression has contributed to differentiation between the two Rocky Mountain populations. White-breasted nuthatches provide a dramatic case of morphological similarity despite high genomic differentiation, and the varying levels of reproductive isolation among the four groups provide an example of the speciation continuum.

Germline-restricted chromosomes of the songbirds.

Germline-restricted chromosomes (GRCs) are present in the genomes of germline cells and absent from somatic cells. A GRC is found in all species of the songbirds (Passeri) and in none of the other bird orders studied to date. This indicates that GRC originated in the common ancestor of the songbirds. The germline-restricted chromosome is permanently absent from somatic cells of the songbird, while female germline cells usually contain two copies of GRC and male ones have one copy. In females, GRCs undergo synapsis and restricted recombination in their terminal regions during meiotic prophase. In males, it is almost always eliminated from spermatocytes. Thus, GRC is inherited almost exclusively through the maternal lineage. The germline-restricted chromosome is a necessary genomic element in the germline cells of songbirds. To date, the GRC genetic composition has been studied in four species only. Some GRC genes are actively expressed in female and male gonads, controlling the development of germline cells and synthesis of the proteins involved in the organization of meiotic chromosomes. Songbird species vary in GRC size and genetic composition. The GRC of each bird species consists of amplified and modified copies of genes from the basic genome of that species. The level of homology between GRCs of different species is relatively low, indicating a high rate of genetic evolution of this chromosome. Transmission through the maternal lineage and suppression of the recombination contribute significantly to the accelerated evolution of GRCs. One may suggest that the rapid coordinated evolution between the GRC genes and the genes of the basic genome in the songbirds might be responsible for the explosive speciation and adaptive radiation of this most species-rich and diverse infraorder of birds.

Living on the edge: Predicting songbird response to management and environmental changes across an ecotone.

Effective wildlife management requires robust information regarding population status, habitat requirements, and likely responses to changing resource conditions. Single-species management may inadequately conserve communities and result in undesired effects to non-target species. Thus, management can benefit from understanding habitat relationships for multiple species. Pinyon pine and juniper (Pinus spp. and Juniperus spp.) are expanding into sagebrush-dominated (Artemisia spp.) ecosystems within North America and mechanical removal of these trees is frequently conducted to restore sagebrush ecosystems and recover Greater Sage-grouse (Centrocercus urophasianus). However, pinyon-juniper removal effects on non-target species are poorly understood, and changing pinyon-juniper woodland dynamics, climate, and anthropogenic development may obscure conservation priorities. To better predict responses to changing resource conditions, evaluate non-target effects of pinyon-juniper removal, prioritize species for conservation, and inform species recovery within pinyon-juniper and sagebrush ecosystems, we modeled population trends and density-habitat relationships for four sagebrush-associated, four pinyon-juniper-associated, and three generalist songbird species with respect to these ecosystems. We fit hierarchical population models to point count data collected throughout the western United States from 2008 to 2020. We found regional population changes for 10 of 11 species investigated; 6 of which increased in the highest elevation region of our study. Our models indicate pinyon-juniper removal will benefit Brewer's Sparrow (Spizella breweri), Green-tailed Towhee (Pipilo chlorurus), and Sage Thrasher (Oreoscoptes montanus) densities. Conversely, we predict largest negative effects of pinyon-juniper removal for species occupying early successional pinyon-juniper woodlands: Bewick's Wren (Thryomanes bewickii), Black-throated Gray Warblers (Setophaga nigrescens), Gray Flycatcher (Empidonax wrightii), and Juniper Titmouse (Baeolophus ridgwayi). Our results highlight the importance of considering effects to non-target species before implementing large-scale habitat manipulations. Our modeling framework can help prioritize species and regions for conservation action, infer effects of management interventions and a changing environment on wildlife, and help land managers balance habitat requirements across ecosystems.

Domains of scale in cumulative effects of energy sector development on boreal birds

ContextIndustrial development in Canada’s boreal forest creates cumulative environmental effects on biodiversity. Some effects may be scale-dependent, creating uncertainty in understanding and hindering effective management.ObjectivesWe estimated cumulative effects of energy sector development on distributions of sixteen migratory songbird species at multiple spatial scales within the boreal region of Alberta, Canada, and evaluated evidence for scale domains in species responses.MethodsWe used a hierarchical, multi-scale sampling and modelling framework to compare effects of oil and gas footprint on songbirds at five spatial scales. We used Bayesian Lasso to facilitate direct comparison of parameter estimates across scales, and tested for differences in grouped parameter estimates among species.ResultsWe found consistent scale-dependent patterns across species, showing variable responses to development occurring at the smallest scale, little effect at intermediate scales, and stronger, mainly positive effects at the largest scales. Differences in grouped parameter estimates across scales showed strong evidence for scale domains in the response of songbirds to energy sector development.ConclusionsWe concluded that variable effects at the smallest scale represented individual habitat selection, while larger scale positive effects reflected expanding distributions of open habitat- and disturbance-associated species in areas of high oil and gas footprint. Our results show that single-scale analyses do not reflect population processes occurring at other scales. Future research on linking patterns at different scales is required to fully understand cumulative effects of land use change on wildlife populations.

Climate change does not equally affect temporal patterns of natural selection on reproductive timing across populations in two songbird species.

Climate change has led to changes in the strength of directional selection on seasonal timing. Understanding the causes and consequences of these changes is crucial to predict the impact of climate change. But are observed patterns in one population generalizable to others, and can spatial variation in selection be explained by environmental variation among populations? We used long-term data (1955-2022) on blue and great tits co-occurring in four locations across the Netherlands to assess inter-population variation in temporal patterns of selection on laying date. To analyse selection, we combine reproduction and adult survival into a joined fitness measure. We found distinct spatial variation in temporal patterns of selection which overall acted towards earlier laying, and which was due to selection through reproduction rather than through survival. The underlying relationships between temperature, bird and caterpillar phenology were however the same across populations, and the spatial variation in selection patterns is thus caused by spatial variation in the temperatures and other habitat characteristics to which birds and caterpillars respond. This underlines that climate change is not necessarily equally affecting populations, but that we can understand this spatial variation, which enables us to predict climate change effects on selection for other populations.

Let's stick together: Infection enhances preferences for social grouping in a songbird species.

Acute infections can alter foraging and movement behaviors relevant to sociality and pathogen spread. However, few studies have directly examined how acute infections caused by directly transmitted pathogens influence host social preferences. While infected hosts often express sickness behaviors (e.g., lethargy) that can reduce social associations with conspecifics, enhanced sociality during infection might be favored in some systems if social grouping improves host survival of infection. Directly assaying social preferences of infected hosts is needed to elucidate potential changes in social preferences that may act as a form of behavioral tolerance (defined as using behavior to minimize fitness costs of infection). We tested how infection alters sociality in juvenile house finches (Haemorhous mexicanus), which are both highly gregarious and particularly susceptible to infection by the bacterial pathogen Mycoplasma gallisepticum (MG). We inoculated 33 wild-caught but captive-held juvenile house finches with MG or media (sham control). At peak infection, birds were given a choice assay to assess preference for associating near a flock versus an empty cage. We then repeated this assay after all birds had recovered from infection. Infected birds were significantly more likely than controls to spend time associating with, and specifically foraging near, the flock. However, after infected birds had recovered from MG infection, there were no significant differences in the amount of time birds in each treatment spent with the flock. These results indicate augmented social preferences during active infection, potentially as a form of behavioral tolerance. Notably, infected birds showed strong social preferences regardless of variation in disease severity or pathogen loads, with 14/19 harboring high loads (5-6 log10 copies of MG) at the time of the assay. Overall, our results show that infection with a directly transmitted pathogen can augment social preferences, with important implications for MG spread in natural populations.

Variation in avian responses to rice intensification in the central plains of Thailand guides conservation opportunities

Multiple studies indicate that grassland and farmland birds are declining in temperate zones, but few have been conducted in the tropics. Here we examined effects of rice intensification on landbird communities and estimated habitat-specific densities of eight songbird species of national and/or global conservation concern in the central plains of Thailand where rice is intensively cultivated often with triple annual rice crops. From 1410 point-counts, we observed 236 species including 26 landbirds of conservation concern. The landbird species community was significantly associated with different intensification levels, with eleven species of concern primarily found in single-cropped fields. Three of the eight focal species (i.e., Horsfield's bushlark Mirafra javanica, Oriental skylark Alauda gulgula, and striated grassbird Megalurus palustris) had lower densities with increased intensification. Natural habitat features (i.e., field margins, reedbeds, and scattered trees) positively influenced densities of all species, even those unaffected by intensification. Densities of Manchurian reed warbler Acrocephalus tangorum, streaked weaver Ploceus manyar, and Asian golden weaver P. hypoxanthus were positively correlated with increases in field margins and reedbeds. Plain-backed sparrow Passer flaveolus density was positively related to presence of scattered trees. Long-tailed shrike Lanius schach density appeared to have a positive correlation with field margins and was significantly negatively correlated with urbanization. Our findings underscore the necessity of adopting policies that encourage wildlife-friendly land management in Southeast Asia, reducing intensification of agricultural landscapes that support species of conservation concern and preserving natural habitat features. Long-term population monitoring is also needed to better understand trends and judge management efficacy.

Long-term decline in Brown-headed Cowbird (Molothrus ater) abundance has not led to less brood parasitism of four riparian songbird species

Long-term decline in Brown-headed Cowbird (Molothrus ater) abundance has not led to less brood parasitism of four riparian songbird species

Songbird species that display more-complex vocal learning are better problem-solvers and have larger brains.

Complex vocal learning, a critical component of human spoken language, has been assumed to be associated with more-advanced cognitive abilities. Tests of this hypothesis between individuals within a species have been inconclusive and have not been done across species. In this work, we measured an array of cognitive skills-namely, problem-solving, associative and reversal learning, and self-control-across 214 individuals of 23 bird species, including 19 wild-caught songbird species, two domesticated songbird species, and two wild-caught vocal nonlearning species. We found that the greater the vocal learning abilities of a species, the better their problem-solving skills and the relatively larger their brains. These conclusions held when controlling for noncognitive variables and phylogeny. Our results support a hypothesis of shared genetic and cognitive mechanisms between vocal learning, problem-solving, and bigger brains in songbirds.

Mercury causes degradation of spatial cognition in a model songbird species

Mercury is a widespread pollutant of increasing global concern that exhibits a broad range of deleterious effects on organisms, including birds. Because the developing brain is well-known to be particularly vulnerable to the neurotoxic insults of mercury, many studies have focused on developmental effects such as on the embryonic brain and resulting behavioral impairment in adults. It is not well understood how the timing of exposure, for example exclusively in ovo versus throughout life, influences the impact of mercury. Using dietary exposure to environmentally relevant methylmercury concentrations, we examined the role that timing and duration of exposure play on spatial learning and memory in a model songbird species, the domesticated zebra finch (Taeniopygia guttata castanotis). We hypothesized that developmental exposure was both necessary and sufficient to disrupt spatial memory in adult finches. We documented profound disruption of memory for locations of hidden food at two spatial scales, cage- and room-sized enclosures, but found that both developmental and ongoing adult exposure were required to exhibit this behavioral impairment. Methylmercury-exposed birds made more mistakes before mastering the spatial task, because they revisited unrewarded locations repeatedly even after discovering the rewarded location. Contrary to our prediction, hippocampal volume was not affected in birds exposed to methylmercury over their lifetimes. The disruption of spatial cognition that we detected is severe and would likely have implications for survival and reproduction in wild birds; however, it appears that individuals that disperse or migrate from a contaminated site might recover later in life if no longer exposed to the toxicant.

Migratory songbirds exhibit seasonal modulation of the oxygen cascade.

Migratory flight requires birds to maintain intensive aerobic exercise for many hours or days. Maintaining O2 supply to flight muscles is therefore important during migration, especially since migratory songbirds have been documented flying at altitudes greater than 5,000 m above sea level, where O2 is limited. Whether songbirds exhibit seasonal plasticity of the O2 cascade to maintain O2 uptake and transport during migratory flight is not well understood. We investigated changes in the hypoxic ventilatory response, haematology, and pectoralis (flight) muscle phenotype of 6 songbird species from 3 families during migratory and non-migratory conditions. Songbirds were captured during southbound migration in southern Ontario, Canada. Half of the birds were assessed during migration, and the rest were transitioned onto a winter photoperiod to induce a non-migratory phenotype and measured. All species exhibited seasonal plasticity at various stages along the O2 cascade, but not all species exhibited the same responses. Broadly, songbirds were more hypoxia tolerant during migration, withstanding 5 kPa O2, and breathed more effectively through slower, deeper breaths. Warblers had a stronger haemoglobin-O2 affinity during fall migration (decrease of ∼4.7 Torr), while the opposite was observed in thrushes (increase of ∼2.6 Torr). In the flight muscle there was an ∼1.2-fold increase in the abundance of muscle fibers with smaller fiber transverse areas during fall migration, but no changes in capillary-fiber ratio. These adjustments would enhance O2 uptake and transport to the flight muscle. Our findings demonstrate that in the O2 cascade there is no ideal migratory phenotype for all songbirds.

Avian Haemosporidians Infecting Short- and Long-Distance Migratory Old World Flycatcher Species and the Variation in Parasitaemia After Endurance Flights

PurposeAvian haemosporidians are widespread parasites, occurring in many bird families and causing pathologies ranging from rather benign infections to highly virulent diseases. The state of knowledge about lineage-specific intensities of haemosporidian infection (i.e., parasitaemia) is mainly based on infection experiments conducted under laboratory conditions. The levels and range of parasitaemia in natural host–parasite associations as well as their influencing factor remain largely unexplored.MethodsThus, we explored the parasitaemia of four songbird species (i.e., European Robins, Black and Common Redstarts and Whinchats) during migration by screening individuals upon landing on an insular passage site after extensive endurance flights to (1) describe their natural host–parasite associations, (2) quantify parasitaemia and (3) explore potential host- and parasite-related factors influencing parasitaemia.ResultsWe found 68% of Whinchats to be infected with haemosporidians, which is more frequent than any other of the studied host species (30–34%). Furthermore, we confirmed that parasitaemia of Haemoproteus infections was higher than average Plasmodium infections. Median parasitaemia levels were rather low (parasite cells in 0.01% of hosts’ red blood cells) and varied largely among the different parasite lineages. However, we found four individuals hosting infections with parasitaemia higher than typical chronic infections.ConclusionsBased on the known transmission areas of the respective lineages, we argue that these higher intensity infections might be relapses of consisting infections rather than acute phases of recent primary infections.

Collocating pipelines to minimize fragmentation: evaluating ecological costs of a shale gas mitigation practice

AbstractShale gas development occurs in forests of the Appalachian Basin within breeding habitat for forest songbirds. Development requires linear infrastructure (e.g., pipelines, gas access roads) that fragments habitat and reduces core forest. Collocation is a mitigation practice that sites new pipelines adjacent to existing surface disturbance such as forest roads; it reduces core forest loss but may have associated ecological costs, defined as negative effects on native species and ecosystems. We conducted a paired sampling design between forest roads and collocated pipelines (expanded gas access roads collocated with pipelines) to evaluate ecological costs to forest songbirds in 2013 in Pennsylvania, USA. We surveyed 4 focal songbird species: 3 territorial species that varied in habitat requirements and the non‐territorial brown‐headed cowbird (Molothrus ater), an obligate brood parasite. We used spot mapping to survey focal species within linear corridors and the adjacent mature forest. Territory density of forest interior ovenbirds (Seiurus aurocapilla) was significantly lower on collocated pipelines (5.1 fewer territories per 10 ha) compared to forest road sites. We found no effect of collocation on territory density for the early successional species, eastern towhee (Pipilo erythrophthalmus) and chestnut‐sided warbler (Setophaga pensylvanica). Territories of all 3 territorial focal species crossed collocated pipeline sites less frequently than forest roads (ovenbird: 16%, eastern towhee: 14%, chestnut‐sided warbler: 31%) and the barrier effect increased with increasing corridor width. In contrast, brown‐headed cowbird abundance was 15 times greater at collocated pipelines compared to forest roads, suggesting that wider gas corridors provide enhanced access routes for cowbirds. Our study indicates the expansion of forest roads to collocated pipelines exacerbates the negative ecological effects already present with the existing road including increased edge avoidance by a forest interior species, greater barrier effects for all 3 territorial forest songbirds, and increased access for brown‐headed cowbirds into core forest. We support collocation as a mitigation strategy but emphasize restricting overall corridor width to reduce the additional ecological costs associated with this practice.

Neuroscience of cognitive control in crows

Crows, a group of corvid songbird species, show superb behavioral flexibility largely stemming from their advanced cognitive control functions. These functions mainly originate from the associative avian pallium that evolved independently from the mammalian cerebral cortex. This article presents a brief overview of cognitive control functions and their neuronal foundation in crows.

Prevalence and diversity of malaria parasites (genus Plasmodium) in the imperiled Saltmarsh Sparrow are greater at northern sites

Abstract Malaria parasites (genus Plasmodium) are important agents of infectious disease in birds and multiple factors, including warming temperatures and environmental contamination, may act to increase their geographic and host ranges. Here, we examined the role of geographical variation and environmental mercury exposure in malaria parasite infection dynamics in an imperiled songbird species with high mercury exposition, the Saltmarsh Sparrow (Ammospiza caudacutus). Using polymerase chain reaction (PCR) methods, we screened 280 Saltmarsh Sparrows from across their breeding range for malaria parasite infection. We detected malaria parasites in 17% of sampled birds and a total of 6 Plasmodium lineages. Prevalence of infection and diversity of parasite lineages varied across the breeding range of the Saltmarsh Sparrow and increased at more northern latitudes. Although mercury is a known immunosuppressant and has been documented to alter an individual’s susceptibility to pathogens, we did not find a significant difference in blood mercury levels between infected and not infected birds, perhaps due to sampling methods and/or small sample sizes. As a specialist of coastal wetlands, the Saltmarsh Sparrow is an excellent indicator species for ecological health, and the patterns of malaria parasite infection with host distribution and mercury suggest that birds at northern latitudes are at greater risk of disease and should be priorities for conservation, habitat, and pathogen monitoring.

Local weather affects body condition of three North American songbird species on the Texas Coast.

Body condition is a frequently used physiological indicator of avian health and can be affected by an array of environmental variables. Although a number of studies have investigated the specific effects of individual weather variables on body condition in birds, few have analyzed the effects of both temperature and precipitation within the context of an extreme weather event such as hurricanes. In this study, we examined the relationship between breeding-season body condition and daily maximum temperature, daily minimum temperature, and monthly total precipitation for three passerine bird species at the Welder Wildlife Refuge near Rockport, Texas. We also evaluated yearly changes in body condition over a 12-year period for northern cardinals (Cardinalis cardinalis), painted buntings (Passerina ciris), and white-eyed vireos (Vireo griseus), focusing on the extreme precipitation event of Hurricane Harvey, which caused heavy localized flooding. We found that body condition declined with average daily minimum and maximum temperatures, while precipitation had varied, species-specific effects in the three species analyzed. Our results also suggest that northern cardinals experienced a notable reduction in average body condition in the 2 years following Hurricane Harvey. Taken together, we conclude that short-term precipitation and temperature drivers can be important correlates of body condition in songbirds and that severe weather events may reduce body condition in some bird species.

Interspecific avoidance of song overlap in tropical songbirds: species-specific responses to acoustically similar and different intruders

To ensure effective acoustic communication, signals should reach receivers in the least distorted form possible. Animals use various short- and long-term strategies to avoid signal degradation and masking. However, we still have an insufficient understanding of how animals’ vocal behaviour is impacted by the vocalisations of other animals in their acoustic communities. We experimentally examined how two tropical, sedentary, territorial songbirds in Western Uganda—the scaly-breasted illadopsis (Illadopsis albipectus) and the green-backed camaroptera (Camaroptera brachyura)—modify their singing behaviour after the simulated appearance of new, unfamiliar acoustic competitors, whose songs vary in similarity to those of the species studied. We found that scaly-breasted illadopsis sang significantly less during the playback of songs of acoustically similar species than of acoustically different species or silence and avoided song overlapping with acoustically similar species but not with acoustically different species. Green-backed camaroptera sang significantly more during the playback of both acoustically similar and different simulated intruders than during the control containing silence, and patterns of overlap with the songs of both the acoustically similar and different species were random. Our results show that even a single-point noise source present within a territory can modify a bird’s singing behaviour. The new sound may affect species differently, depending in part on the level of acoustic similarity with the species’ song. To mitigate the effect of song masking, different species may use different strategies, such as temporal avoidance or signal redundancy. Studies examining the adaptive abilities of species in natural and modified habitats are needed to predict the consequences of changes in acoustic community structure.Significance statementTo ensure effective communication, birds may use different strategies to avoid signal masking in common acoustic space, particularly in the complex acoustic environment of a tropical forest. While multiple studies have focused on responses to interference caused by anthropogenic noise, the effect of new individual species on the acoustic community structure has received little attention. We simulated intrusions by unfamiliar species with different levels of song similarity into the territories of two tropical songbird species. The appearance of new simulated acoustic intruders modified the birds’ singing behaviour, but the two study species responded differently. These results suggest that the level of acoustic similarity, as well as the species ecology, may affect the species response, which may be particularly important when predicting the effects of new species appearance as a result of changes in habitat and climate.

Riskiness of Movement Lifestyle Varies Inversely with Adult Survival Probability among Species.

AbstractWhy do species differ in their movement lifestyles? Animals that spend more time sitting motionless and acquire food using less conspicuous movements can be more vigilant and less obvious to predators. More active animals that use food types and sites that require more conspicuous behaviors increase vulnerability to predators. Life history theory predicts that aversiveness to mortality risk evolves inversely to adult survival probability. Consequently, we postulated that long-lived species evolved inconspicuous movement lifestyles, whereas shorter-lived species use more conspicuous movement lifestyles. We tested this hypothesis by quantifying the movement lifestyles of nine tropical songbird species. Use of conspicuous movement and foraging behaviors, such as flying and hovering, was greatest in shorter-lived species and decreased with increasing adult survival probability across species. Similarly, foraging speed decreased with increasing adult survival based on a meta-analysis of 64 songbird species. Faster and conspicuous movement lifestyles of shorter-lived species likely increase food acquisition rates, which fits with faster life history strategies that include more feeding trips for young and faster growth. Similarly, slow movement lifestyles of long-lived species fit with the reduced food needs of slower life history strategies. Movement lifestyles may have evolved as an integrated component of the slow-fast life history continuum.

Comparison of impacts of oil infrastructure on grassland songbirds between landscape-scale noise addition and noise removal experiments

As anthropogenic noise becomes increasingly widespread in natural habitats, noise addition and removal studies have become an important and commonly used method to assess the effects of noise on wildlife. Despite their wide implementation, it is difficult to determine whether the results from these studies translate to natural environments. Oil extraction operations provide a unique opportunity to conduct large-scale natural and experimental noise studies because they emit high-amplitude noise and are subject to interruptions or cessation of operations. We conducted a 6-year study aimed at identifying the effects of different types of oil infrastructure and noise on four species of grassland songbirds in the Canadian prairies. We measured abundance and nesting success of our focal species and compared between a large-scale playback experiment (i.e., noise addition) and in response to real infrastructure (i.e., noise removal). We also conducted an in-depth species analysis of reproductive output, stress, and population structure of an endangered species, Chestnut-collared Longspur ( Calcarius ornatus ). This multi-species and species-specific approach enabled us to assess noise impacts that may vary among species and for different life-history traits. Overall, our comparative study suggests that noise addition experiments can result in different conclusions regarding the ecological impacts of noise generated from in situ field studies in sites with associated disturbances. While noise clearly impacts birds in many ways, when layered with the many other ecosystem changes associated with real-world oil extraction activity, the effects of noise may be less prominent. As such, caution must be taken when applying results of noise experiments to conservation and management plans and regulations, as effects of noise predicted by lab and field noise addition experiments may simply not be realized under real-world conditions.