Peregrine Research Articles

Environmental conditions experienced upon first breeding modulate costs of early breeding but not age-specific reproductive output in peregrine falcons.

Although once considered uncommon, there is growing evidence of widespread senescence in wildlife populations. However, few studies have examined the traits involved, inter-sexual differences, and environmental correlates of age-specific performance in raptors. We studied age-specific reproductive performance and actuarial senescence (decrease in survival probability with age) in a peregrine falcon population monitored for 21 years. We analysed changes with age in the number of offspring produced and incubation start date. We also inspected variation in lifespan and breeding lifespan (number of breeding occasions in a lifetime). In every case, we assessed associations between variations in traits and age, sex, recruitment age, and environmental conditions (cumulative rainfall during breeding season) experienced upon the first breeding attempt. We found scarce evidence for reproductive senescence. Only the incubation start date in females, which was delayed after approximately 8 cy (calendar years), suggested reproductive senescence in our study population. Regarding actuarial senescence, our data did not support it as we only found evidence of higher juvenile mortality. Furthermore, expected lifespan in peregrines recruited at 2 cy was associated with conditions experienced upon the first breeding attempt. The lifespan and breeding career of individuals recruited as yearlings and experiencing low rainfall upon first breeding did not significantly differ from those recruited as adults. However, those recruited as yearlings and experiencing poor environmental conditions upon the first breeding attempt showed reduced lifespan and breeding lifespan.

Does fluctuating selection maintain variation in nest defense behavior in Arctic peregrine falcons (Falco peregrinus tundrius)?

Behavioral expression can vary both within‐ (i.e., plasticity) and among‐individuals (i.e., animal personality), and understanding the causes and consequences of variation at each of these levels is a major area of investigation in contemporary behavioral ecology. Here, we studied sources of variation in both plasticity and personality in nest defense behavior in Arctic peregrine falcons (Falco peregrinus tundrius) in two consecutive years. We found that peregrines adjusted their nest defense in response to nesting stage and year, revealing plastic, state‐dependent, adjustment of nest defense. At the same time, nest defense behavior was repeatable in peregrine falcons both within and between years. We tested if fluctuating selection on behavioral types (i.e., individuals average phenotypic expression) and/or assortative mating acted to maintain long‐term among‐individual differences in nest defense behavior. We found that selection on female nest defense differed across years; being positive in 1 year and negative in the other. We also found support for assortative mating in the first year, but disassortative mating in the second. We propose two potential explanations for the observed year‐specific patterns of nonrandom mating: (1) year‐specific plastic adjustment of nest defense and/or (2) changes in the age‐structure of the breeding population. These posthoc explanations are speculative, and require further study. Unfortunately, we could not evaluate this directly with the available data, and future studies are needed with more than 2 years of data on nest‐defense and fitness outcomes, and with a larger number of marked individuals, to properly evaluate these potential explanations.

Swamps as habitats of rare raptor species in the Nizhny Novgorod region

This article presents relevant contribution to the distribution and number of six species of birds of prey listed in the Red Data Book of RF, in the territory of swamps in the Nizhny Novgorod region. Three species of rare birds of prey in the Nizhny Novgorod region demonstrate a very strong relationship with the swamps of the region - Golden Eagle, Short-toed Eagle and Osprey. All the nesting sites of Golden Eagles are rigidly connected with bog complexes; 66.1% sites of the Short-toed Eagle sites are located in swamps. Osprey can also nest along rivers, but, most likely, the loss of densely located nesting sites in bogs (45.8%) will lead to catastrophic consequences for the species. The Greater Spotted Eagle and White-Tailed Eagle are associated with swamps for the second time, and their rates are 11.8% and 11.7%. Earlier the Peregrine Falcon in the region had a significant percentage of nesting sites in wetlands (26.7%), but now seems to be lost as a breeding species. The total percentage of neting sites located in wetlands for all raptor species listed in the Red Data Book of RF in the Nizhny Novgorod region is 39.5%. All the species under consideration are bioindicators of wetlands and adjacent habitats and allow assessing the conditions of this habitat.

The digital peregrine: A technonatural history of a cosmopolitan raptor

AbstractHumans, non‐human animals, and technologies are increasingly entangled. Using the peregrine falcon (Falco peregrinus) as an illustrative example, we propose ‘technonatural history’ as a theoretical and methodological approach for observing, describing, and examining the role technologies play in shaping human relations with other species. After nearing extinction in the 20th century, peregrines have become woven into the fabric of everyday urban life and are a frequently sighted urban raptor in the UK, nesting on high‐rise buildings and church spires since the late 1990s. Their unexpected presence in cities symbolises hope for multispecies conviviality amid the contemporary ecological crisis. As their populations resurged, crucially, webcam and livestreaming technologies developed rapidly. Peregrines were one of the first animals to be broadcast over the internet via ‘nestcams’, granting broad publics access to their intimate lives. We examine the related technological histories of livestreaming technologies and natural histories of peregrine falcons in the UK, tracing the emergence of ‘the digital peregrine’ and its manifold implications for more‐than‐human and digital geographies. To do so, we build on oral history interviews with people associated with digital peregrines throughout the UK: nestcam technicians, peregrine conservationists, professional ecologists, activists, and citizen scientists. While digitisation brings broad publics closer to these cosmopolitan raptors, they can only ever grasp at the wildness of peregrine falcons and their wider milieus as the digital peregrine is a distinct entity, encountered via its own set of affects and affordances. In the peregrine's case, digital technologies create unexpected and radical opportunities for urban conviviality, signalling the positive potentials technologies host for forging meaningful more‐than‐human connections.

Evaluation of the Impact of the Peregrine Falcon (Falco peregrinus peregrinus) Reintroduction Process on Captive-Bred Population.

The main objective of this study was to determine the impact of increased demand for peregrine falcons via breeding (mainly Polish, Czech, German and Slovak) on the genetic structure of the birds. In the analysis, 374 specimens from six countries were sampled in 2008–2019 (omitting 2009), and all the birds analyzed were released into the wild as part of the Polish reintroduction program. The assessment of genetic variation was based on a well-known panel of 10 microsatellite markers described for the species. We calculated a fixation index for the samples from each year, and based on this, we determined the level of inbreeding. We also performed an analysis using the Bayesian cluster method, assuming that 1–19 hypothetical populations would define the division that best fit the samples. The most probable division was into two groups; in the first group, the samples from individuals delivered in 2013 were most often segregated; moreover, in this year, a jump in inbreeding, expressed by the fixation index, was observed.

THE MURMURATIONS OF EUROPEAN STARLINGS; AN ANTI-PREDATOR STRATEGY AND A HISTORICAL MISNOMER

I report on the predatory interaction of Peregrine Falcons and flocks of European Starlings in British Columbia, and I review the literature of raptors hunting starlings at their roost sites in Europe. A video analysis of peregrines attacking roosting flocks of starlings over Rome is compared to my long-term observations of peregrines hunting passerines and sandpipers in Canada. The results suggest that the starling murmurations are an anti-predator strategy. My observations, and a review of historical notes in the Oxford English Dictionary, show that the term murmuration was originally inspired by the chorus song of breeding starlings and that today's common use of that term to describe their roost site flights is a misnomer.

Peregrine Falcon Steals Prey from White-tailed Kites

Peregrine Falcon Steals Prey from White-tailed Kites

The DDT‐induced decline influenced genetic diversity in naturally recovered Peregrine falcons (Falco peregrinus) nesting within the Alaska Arctic and eastern interior

We assessed the influence of the severe mid‐20th century population decline on genetic diversity in non‐augmented Peregrine Falcon Falco peregrinus populations nesting within the Alaska Arctic and eastern Interior. Microsatellite and mitochondrial DNA (mtDNA) data were analysed for Peregrine Falcons sampled from three periods: pre‐decline, decline and post‐decline. The influence of the decline on genetic diversity differed between the two locales. The Alaska Arctic was characterized by shifts in mtDNA haplotype frequencies, increased inbreeding coefficient, reduction in effective population size and increase in private haplotypes, and a signature of post‐decline population growth was detected; by contrast, the eastern Interior showed a reduction in haplotype diversity and no differences in allelic or haplotypic frequencies between pre‐ and post‐decline periods, though pre‐decline birds clustered away from the other two periods and allelic frequency differences were observed between decline and post‐decline periods. Patterns in genetic diversity suggest populations recovered through recruitment from within and immigration.

Has the Australian Endemic Grey Falcon the Most Extreme Dietary Specialization among all Falco Species?

Simple SummaryThe diet of an animal is one of the most informative aspects of how it interacts with its environment. A clear understanding of a species’ diet is, therefore, crucial for conservation considerations. The Grey Falcon is a rare and threatened raptor, found only in Australia’s vast arid and semi-arid zone. Its diet is subject to dispute, therefore, we studied, through direct observation during more than 17 years of fieldwork, the food that these birds ingested. We found that Grey Falcons of all ages fed almost exclusively on birds. No other food type was ever taken with any regularity. Our results suggest strongly that the Grey Falcon, throughout the year, throughout its life, and across its vast distribution, feeds almost exclusively on birds. We compared our results with the diets of the other species in the genus (Falco) and found that the Grey Falcon’s diet is the most extreme, more so than the diet of even those falcon species that are commonly considered to take exclusively birds, such as the Peregrine Falcon. Our evolutionary explanation of the unique dietary specialization of the Grey Falcon takes into account aspects of the species’ environment and relative prey availability.A clear understanding of a species’ diet is crucial in understanding its spatio-temporal dynamics, and is, therefore, pertinent to conservation considerations. The diet of the Grey Falcon (Falco hypoleucos), a rare and threatened predator endemic to the Australian arid and semi-arid zone, is subject to diverging assertions; therefore, we studied its diet through direct observation of food ingestion during more than 17 years of fieldwork across the species’ distribution. We found that Grey Falcons of all ages fed almost exclusively on a single type of food, namely, birds, and non-avian food items never constituted a substantial portion of any individual’s diet. The extraordinary circumstances that were associated with the ingestion of non-avian food suggest strongly that, across its vast distribution, throughout the year, and throughout its life, the Grey Falcon feeds almost exclusively on birds. Further, we compared the diets of all Falco species and found that the dietary specialization is most extreme in the Grey Falcon, more so than even in the Taita (F. fasciinucha) and Peregrine Falcons (F. peregrinus). Based on aspects of the species’ environment and relative prey availability, we offer an evolutionary explanation of the apparently unique dietary specialization of the arid-adapted Grey Falcon.

Distribution and habitat use of the Madagascar Peregrine Falcon: first estimates for area of habitat and population size

SummaryAccurately demarcating distributions of biological taxa has long been at the core of ecology. Yet our understanding of the factors defining species range limits is incomplete, especially for tropical species in the Global South. Human-driven threats to the survival of many taxa are increasing, particularly habitat loss and climate change. Identifying distributional range limits of at-risk and data-limited species using Species Distribution Models (SDMs) can thus inform spatial conservation planning to mitigate these threats. The Madagascar Peregrine FalconFalco peregrinus radamais the resident sub-species of the Peregrine Falcon complex distributed across Madagascar, Mayotte, and the Comoros Islands. There are currently significant knowledge gaps regarding its distribution, habitat preferences, and population size. Here, we use penalized logistic regression and environmental ordination to identify Madagascar Peregrine Falcon habitat in both geographic and environmental space and propose a population size estimate based on inferred habitat. From the penalized logistic regression model, the core habitat area of the Madagascar Peregrine Falcon extends across the central and northern upland plateau of Madagascar with patchier habitat across coastal and low-elevation areas. Range-wide habitat use in both geographic and environmental space indicated positive associations with high elevation and aridity, coupled with high vegetation heterogeneity and >95% herbaceous landcover, but general avoidance of areas >30% cultivated land and >10% mosaic forest. Based on inferred high-class habitat from the penalized logistic regression model, we estimate this habitat area could potentially support a population size ranging between 150 and 300 pairs. Following IUCN Red List guidelines, this subspecies would be classed as ‘Vulnerable’ due to its small population size. Despite its potentially large range, the Madagascar Peregrine Falcon has specialised habitat requirements and would benefit from targeted conservation measures based on spatial models to maintain viable populations.

Linked-Read Sequencing of Eight Falcons Reveals a Unique Genomic Architecture in Flux.

Falcons are diverse birds of cultural and economic importance. They have undergone major lineage-specific chromosomal rearrangements, resulting in greatly reduced chromosome counts relative to other birds. Here, we use 10X Genomics linked reads to provide new high-contiguity genomes for two gyrfalcons, a saker falcon, a lanner falcon, three subspecies of peregrine falcons, and the common kestrel. Assisted by a transcriptome sequenced from 22 gyrfalcon tissues, we annotate these genomes for a variety of genomic features, estimate historical demography, and then investigate genomic equilibrium in the context of falcon-specific chromosomal rearrangements. We find that falcon genomes are not in AT–GC equilibrium with a bias in substitutions toward higher AT content; this bias is predominantly but not exclusively driven by hypermutability of CpG sites. Small indels and large structural variants were also biased toward insertions rather than deletions. Patterns of disequilibrium were linked to chromosomal rearrangements: falcons have lost GC content in regions that have fused to larger chromosomes from microchromosomes and gained GC content in regions of macrochromosomes that have translocated to microchromosomes. Inserted bases have accumulated on regions ancestrally belonging to microchromosomes, consistent with insertion-biased gene conversion. We also find an excess of interspersed repeats on regions of microchromosomes that have fused to macrochromosomes. Our results reveal that falcon genomes are in a state of flux. They further suggest that many of the key differences between microchromosomes and macrochromosomes are driven by differences in chromosome size, and indicate a clear role for recombination and biased gene conversion in determining genomic equilibrium.

Climate Effects on Breeding Phenology of Peregrine and Lanner Falcons in the Mediterranean

We explored the effects of weather on the timing and reproduction of the Mediterranean Peregrine Falcon Falco peregrinus brookei and the Lanner Falcon F. biarmicus feldeggii living on the Mediterranean island of Sicily. We found that the start date of incubation has changed during 1979–2019 and analysed whether incubation timing affected the productivity of both populations and whether the change of incubation date and the quality of breeding sites depended on climatic conditions. Overall spring temperature and rainfall increased on Sicily and the incubation date of the Peregrine and the Lanner Falcon has shifted to be about one week later over the time period 1979 to 2019. Linear mixed modelling showed the influence of winter conditions and random effects (climate sector of island, year of study) on incubation date in both species. The increase in February rainfall has delayed incubation in the Peregrine Falcon, while we could not identify a specific monthly effect delaying incubation in the Lanner Falcon. In both species, the shift in incubation date has resulted in a decrease in productivity (number of fledglings). Weather conditions in late spring predicted the quality of the breeding site of Lanner Falcons but not of Peregrines. The breeding phenology of both falcons shows a common response to weather conditions on Sicily, however the Lanner Falcon seems more sensitive than the Peregrine to the changing climate. Climate effects add to other anthropogenic impacts negatively affecting the future survival of this insular population, which is the largest in Europe.

A Novel Dipotassium Hydrogen Phosphate Phantom for Calibrating Computed Tomographic Bone Density Measurements in Birds.

The objective of this study was to construct a calibration phantom for bone mineral density (BMD) measurements adapted to avian anatomy by quantitative computed tomography. The determination of BMD is important to assess avian osteoporosis in poultry at production facilities and to study biological features in association with flight patterns in birds. Quantitative computed tomography measured in Hounsfield units is a well-established technique for BMD measurements. Translation of Hounsfield units into the International System of Units (mg/cm3) requires the use of a calibration phantom. Although calibration phantoms for routine use in humans are commercially available, phantoms suited to avian anatomy are not. A liquid dipotassium hydrogen phosphate calibration standard was constructed out of commercially available materials, easily allowing for variations in size, bone diameter, and adaptation to avian skeletal anatomy. Periodically, quantitative computed tomography scans were performed to monitor constant correlation to the calibration standard over 3 months and to monitor for the potential influence of gas bubbling and water evaporation in the rods on BMD measurements. Finally, the calibration phantom was tested for BMD measurements with carcasses from 2 bird species, including 3 peregrine falcons (Falco peregrinus; 2 juvenile males, 1 adult female with inactive reproductive status) and 4 Eurasian kestrels (Falco tinnunculus; 1 juvenile and 2 adult males, 1 adult female with inactive reproductive status). Results demonstrated stability of the calibration phantom without the need to refill or replace rods, plus a stable correlation line (R 2 = .99) over the 3-month evaluation period. It was possible to place the phantom directly on the bird carcasses, close to the measured bones, to improve BMD analysis. As evaluated, the phantom appeared to be adaptive to avian skeletal anatomy. Moreover, it was possible to build the phantom within 24 hours from commercially available materials.

Quantitative analysis of the morphing wing mechanism of raptors: Analysis methods, folding motions, and bionic design of Falco Peregrinus

Raptors can change the shape and area of their wings to an exceptional degree in a fast and efficient manner, surpassing other birds, insects, or bats. Some researchers have focused on the functional properties of muscle skeletons, mechanics, and flapping robot design. However, the wing motion of the birds of prey has not been measured quantitatively, and synthetic bionic wings with morphing abilities similar to raptors are far from reality. Therefore, in the current study, a 3D suspension system for holding bird carcasses was designed and fabricated to fasten the wings of Falco Peregrinus with a series of morphing postures. Subsequently, the wing skeleton of the falcon was scanned during extending motions using the computed tomography (CT) approach to obtain three consecutive poses. Subsequently, the skeleton was reconstructed to identify the contribution of the forelimb bones to the extending/folding motions. Inspired by these findings, we propose a simple mechanical model with four bones to form a wing-morphing mechanism using the proposed pose optimisation method. Finally, a bionic wing mechanism was implemented to imitate the motion of the falcon wing—divided into inner and outer wings with folding and twisting motions. The results show that the proposed four-bar mechanism can track bone motion paths with high fidelity.

Danger, risk and anti‐predator behavior in the life history of long‐distance migratory sandpipers

Two recent and independent studies both estimate substantially lower survival rates of semipalmated Calidris pusilla than of western C. mauri sandpipers, consistent with the pronounced multi‐decade population decline of the former. Migratory danger has climbed steadily for both these long‐distance migrants since the mid‐1970s as the number of peregrine falcons Falco peregrinus increased. These predators are present on the Pacific flyway as co‐migrants and are a natural (though now more abundant) feature of western sandpiper southbound migrations. Adjustments to migratory speed, timing and routing enable them to mitigate the danger. On the Atlantic flyway peregrines were introduced and breeding populations established in the 1980s at key staging areas, creating a novel hazard for southbound semipalmated sandpipers. Adjustments to migratory timing and speed do not aid in eluding such resident predators, and alternative routes are not available. Semipalmated sandpipers as a consequence have few effective defenses to counter this heightened danger, and we hypothesize that migratory mortality has increased, making over‐summering (i.e. skipping a breeding season) more advantageous. The risk effects (i.e. the consequent reduction in population growth rate) so generated are substantial, and may be able to account for a large portion of the population decline.

The Recovery of the American Peregrine Falcon in Alaska

American Peregrine Falcons nesting along Alaska’s upper Yukon River have been studied for nearly 50 years. Peregrine populations decreased in the 1960’s because widespread use of the insecticide DDT caused their eggshells to thin. Thin eggshells meant that eggs crushed easily in the nest, which reduced the number of baby birds produced. Eventually, Peregrine Falcons were listed as endangered under the Endangered Species Act in the United States (U.S.). After the U.S. banned the use of DDT, the U.S. Fish and Wildlife Service, National Park Service, and others helped Peregrine Falcons recover. Today, upper Yukon River Peregrine Falcons have rebounded and are thriving. The Peregrine Falcon’s recovery in the U.S. is a shining success story of the Endangered Species Act, although climate change and other pollutants create continuing challenges for the species.

Causes, temporal trends, and the effects of urbanization on admissions of wild raptors to rehabilitation centers in England and Wales.

Data from wildlife rehabilitation centers (WRCs) can provide on‐the‐ground records of causes of raptor morbidity and mortality, allowing threat patterns to be explored throughout time and space. We provide an overview of native raptor admissions to four WRCs in England and Wales, quantifying the main causes of morbidity and mortality, trends over time, and associations between threats and urbanization between 2001 and 2019. Throughout the study period, 14 raptor species were admitted totalling 3305 admission records. The Common Buzzard (Buteo buteo; 31%) and Tawny Owl (Strix aluco; 29%) were most numerous. Relative to the proportion of breeding individuals in Britain and Ireland, Peregrine Falcons (Falco peregrinus), Little Owls (Athene noctua), and Western Barn Owls (Tyto alba) were over‐represented in the admissions data by 103%, 73%, and 69%, respectively. Contrastingly Northern Long‐eared Owls (Asio otus), Western Marsh Harriers (Circus aeruginosus), and Merlin (Falco columbarius) were under‐represented by 187%, 163%, and 126%, respectively. Across all species, vehicle collisions were the most frequent anthropogenic admission cause (22%), and orphaned young birds (10%) were most frequent natural cause. Mortality rate was highest for infection/parasite admissions (90%), whereas orphaned birds experienced lowest mortality rates (16%). For one WRC, there was a decline in admissions over the study period. Red Kite (Milvus milvus) admissions increased over time, whereas Common Buzzard and Common Kestrel admissions declined. There were significant declines in the relative proportion of persecution and metabolic admissions and an increase in orphaned birds. Urban areas were positively associated with persecution, building collisions, and unknown trauma admissions, whereas vehicle collisions were associated with more rural areas. Many threats persist for raptors in England and Wales, however, have not changed substantially over the past two decades. Threats associated with urban areas, such as building collisions, may increase over time in line with human population growth and subsequent urban expansion.

A new cluster of West Nile virus lineage 1 identified in Spain

<h3>Purpose</h3> West Nile Virus (WNV) is a zoonotic arbovirus worldwide spread. In Spain, its active circulation provokes outbreaks in birds, horses and lately in humans. In September 2017, an outbreak affecting raptors, in the province of Málaga (Andalusia), was investigated. One northern goshawk (<i>Accipiter gentilis</i>) died, while two peregrine falcons (<i>Falco peregrinus</i>) recovered. Here we report the isolation and characterization of a new WNV lineage 1 variant from this outbreak. <h3>Methods & Materials</h3> Heart, feathers, brain and kidney samples from the goshawk were collected and firstly analysed by real-time RT-PCR for WNV (Jiménez-Clavero <i>et al</i>., 2006, https://doi.org/doi:10.1177/104063870601800505). Virus isolation was performed in BSR and Vero cells. The whole genome of the isolate was sequenced by Sanger method. Phylogenetic analyses were performed including a wide range of representatives of: 1) all described WNV lineages, and 2) the different clusters of WNV lineage 1. <h3>Results</h3> All samples from the goshawk were positive for WNV lineage 1 by RT-PCR. Virus isolation was successful in heart and brain samples. A full genome sequence of 10,919 nt was obtained for the WNV isolated from the brain (named Spain/2017/NG-b). Phylogenetic analyses confirmed that Spain/2017/NG-b belonged to WNV clade 1a. Surprisingly, this isolate was placed neither in the cluster 2 of this clade, which comprises most of the recent European and Mediterranean strains (including the preceding Spanish ones), nor in other closest clusters. When analysing the polyprotein, amino acid substitutions that define WNV clusters 1-4 were not found in Spain/2017/NG-b isolate (May <i>et al.</i>, 2011, https://doi.org/10.1128/jvi.01963-10). Moreover, it presented 12 unique residues compared to cluster 2 viruses. <h3>Conclusion</h3> These results strongly support that Spain/2017/NG-b represents a new, independent introduction of WNV into the Western Mediterranean since it showed no close relationship to other strains from this region. Therefore, we propose to associate this variant to a new cluster 7 within WNV clade 1a. Finally, a WNV outbreak occurred in equids in December 2017, nearby the raptors´ outbreak above mentioned, suggests the ability of this new variant to infect and cause disease also in horses.

Announcing the 2021 Journal of Experimental Biology Outstanding Paper Prize shortlist and winner.

Announcing the 2021 Journal of Experimental Biology Outstanding Paper Prize shortlist and winner.

Histomorphometrical study of the tongue epithelium of the peregrine falcon (Falco peregrinus).

The aim of this study is to examine the dorsal lingual epithelium of the peregrine falcon (Falco peregrinus) of the family Falconidae. The tongue in its dorsal, lateral and ventral surfaces is covered with a non-keratinized multilayered stratified squamous epithelium. Lamina propria is present beneath the epithelial layers. Morphometrically, thickness of the apex tongue epithelium is more than that in the tongue body. Thickness of the ventral surface of the tongue is less than that in the dorsal one. Thickness of the lateral surface of the tongue was thicker than that in the ventral one and tongue body. Large and small conical papillae appeared on the posterior dorsal surface of the lingual body. There are lingual glands in certain areas of tongue body with numerous openings through the dorsal surface.