Aplomado Research Articles

Using camera traps to inform reintroduction success and recovery of the Northern Aplomado Falcon (Falco femoralis septentrionalis)

Anthropogenic disturbances, including habitat changes, climate change, and pesticides, contribute significantly to species declines and extinctions worldwide. These disturbances also hinder conservation efforts like species reintroductions by creating novel ecosystems that no longer support the species that is being reintroduced. Using camera traps, we observed Great Horned Owls (Bubo virginianus), which are a dominant avian predator, perching on the nests of Northern Aplomado Falcons (Falco femoralis septentrionalis), a federally endangered species reintroduced to coastal Texas with a current breeding population of 23 pairs. The presence of Great Horned Owls on five of the twenty cameras placed on Northern Aplomado Falcon nest structures led us to consider the impact this interaction may have on occupancy and productivity of the nests. Throughout the study system, fast-growing tree and shrub species have become more prominent, which could be facilitating the interaction. We hypothesize that encroachment of woody vegetation is drawing Great Horned Owls into the open coastal grassland habitat of Northern Aplomado Falcons, which may limit the occupancy and productivity of falcon nests. Based on this hypothesis from the camera trap observations and anecdotal evidence of habitat encroachment, quantifying this relationship is a key next step in the recovery process. This will enable us to define priority areas for targeted restoration to push back woody vegetation, as well as areas best suited to release Northern Aplomado Falcons that will minimize the likelihood of predation by Great Horned Owls.

Trio of Aplomado Falcons Captures a Swallow-Tailed Kite

Trio of Aplomado Falcons Captures a Swallow-Tailed Kite

Long-term demography of a reintroduced population of endangered falcons

We examined long-term demography of an endangered subspecies, the Northern Aplomado Falcon ( Falco femoralis septentrionalis ), in South Texas, USA. The population has been managed and monitored since reintroductions began in 1993. Data spanning 1993–2018 enabled us to build an integrated population model (IPM) and a Cormack-Jolly-Seber model to estimate survival for three life stages (first-year, non-breeders, and breeders) and both sexes, abundance of males, fecundity, immigration, and emigration. Male falcons survived at lower rates than females during their first year; Hurricane Harvey caused a decline in survival rates of first-years and breeders; and fecundity increased after 2011 coinciding with changes in management focused on improving nest platforms and habitat quality. Both immigration of non-breeders and emigration were likely negligible for this population suggesting a potentially isolated population. The IPM likely overestimated immigration of breeders warranting further research. Population growth rates were greatest during years having more released captive-reared young and greater probabilities of breeder survival. Importantly, an apparent decrease in breeder survival of unknown cause occurred during 2006–2009 when breeder survival declined and remained low for several years. Our ability to identify the cause for reduced survival is now greatly hampered by the extended time that has passed, limiting the usefulness of this recent awareness for informing management and further highlighting the importance of real-time monitoring for proactive decision making processes. Our study greatly improves knowledge of demographics for a reintroduced, isolated, and intensively managed population of Aplomado Falcons. Applying this IPM to new data each year will enable adaptive management of the South Texas population by providing annual evaluations of vital rates along with revised assessments of monitoring and management. • We created an IPM to evaluate vital rates and management of Aplomado Falcons. • Hurricane Harvey caused a decline in survival of first-years and breeders. • Emigration was trivial, and immigration was likely trivial but needs more study. • Breeder survival was an important vital rate, and declined during 2006–2009. • Management of artificial nest boxes, habitat, and hacking improved vital rates.

Retrospective Study of Fractures in both Appendicular and Axial Skeletons of Birds Belonging to the Families Falconidae and Cariamidae

This retrospective study aimed to identify and classify fractures in the appendicular and axial skeletons of birds from the Cariamidae and Falconidae families presented to a referral centre. Twelve of thirteen adult red-legged seriemas (Cariama cristata) had appendicular skeleton fractures and one an axial skeleton fracture. All appendicular skeleton fractures occurred in pelvic limbs, but one bird also had a thoracic limb fracture. Among the long-bone fractures, ten were of the tibiotarsus. Among these fractures, six were comminuted, two transverse and two spiral. One seriema had an ulnar spiral fracture, and two had exposed fractures of the tibiotarsus. The Falconidae included nine Carcara plancus, five Falco sparverius and two Falco femoralis. Appendicular skeleton fractures were detected in 14 Falconidae, axial skeleton fractures in one,and another bird had fractures in both skeletons. Three fractures occurred in pelvic limbs, and the other was thoracic limb fractures. Out of all the long-bone fractures, eight were found in the humerus, three of which were exposed, two comminuted, two spiral, and one oblique. Four ulna fractures were found; two of them were comminuted, one spiral and transverse. There were two comminuted radius fractures. Tibiotarsus fractures included two transversal and one comminuted fracture. In conclusion, in both families the highest prevalence of fractures was in the appendicular skeleton; however, the fractures in Cariamidae occurred mainly in the pelvic limbs, whereas the fractures in Faconidae were found more frequently in the thoracic limbs.

Temporal Genetic Diversity and Effective Population Size of the Reintroduced Aplomado Falcon (Falco femoralis) Population in Coastal South Texas

Reintroductions are an important tool in conservation for preserving and enhancing biodiversity and preventing extinction, and post-release monitoring is essential to evaluate and inform conservation management and maximize recovery success. By quantifying genetic diversity levels and effective population size (Ne) over time, managers can gauge to what degree additional efforts are needed to increase the likelihood of population persistence. The endangered Northern Aplomado Falcon (Falco femoralis septentrionalis) population in South Texas was reestablished and supplemented with captive-bred individuals originating from 27 founders collected in eastern Mexico (San Luis Potosí, Veracruz, Tabasco, and Chiapas). A total of 927 Aplomado Falcons were released at 23 locations along the southern coast of Texas between 1985 and 2004, and in 2012 and 2013. To assess the species' reintroduction and recovery, we applied a genetic monitoring approach using sampled nestlings (n = 267) from a total of 108 nests in 2004–2005 and 2012–2016. Based on ten microsatellite loci, levels of genetic diversity (i.e., allelic richness and heterozygosity) remained stable over the sampled time period, with no indication of inbreeding. Diversity levels were comparable to a subset of samples collected from the captive population founders (n = 11). Similarly, individuals from the South Texas population showed strong admixture with the founding population, and levels of both Ne and of effective breeding (Nb) showed no signs of decline over the sampled time period. To what degree overlapping generations and the release of additional Aplomado Falcons during the sampled time period limited our assessment of the South Texas population is not fully known. Continued monitoring across multiple generations is advisable to assess the population's ability to persist.

Natal Dispersal of Aplomado Falcons in Chihuahua, Mexico

The persistence of a species throughout its geographic range requires dispersal among its populations. The study of dispersal is particularly relevant for species whose geographic range has contracted, such as the endangered Northern Aplomado Falcon (Falco femoralis septentrionalis). We used Argos 5-g PTT-100 satellite transmitters to determine the movements of two wild Chihuahuan Desert Aplomado Falcons (one female and one male) from fledging to breeding (male), or transmitter failure (female), at 1062 d and 439 d of age, respectively. Both falcons dispersed from their natal territories 2–3 mo after fledging. These falcons then wandered between activity centers near historic breeding territories and some territories recently converted to farmlands. These two falcons also explored areas outside known breeding areas via some long-distance movements to areas of potential breeding habitat being converted to farmland. In 2 yr, movements of the male covered 7412 km2. This falcon nested unsuccessfully with an unbanded female in a vacant breeding territory 15 km from his natal site. His nesting attempt the following year yielded two fledglings. While a breeding bird, the male falcon had a home range of 200 km2. For 17 mo, the female falcon wandered through an area of 12,136 km2. The farthest distance she traveled from her nest site prior to transmitter failure was 154 km.

Inventario avifaunístico de Poza Rica, Veracruz, México

La urbanización se ha extendido de forma acelerada y ha modificado los ambientes donde habitan las aves. Generalmente, los ambientes urbanos conllevan una serie de modificaciones al entorno que derivan en cambios en la composición de aves y en la necesidad de realizar inventarios de éstas. El estado de Veracruz concentra más del 60% de la avifauna mexicana, pero hay zonas donde su conocimiento es aún deficiente, como la zona norte. En este estudio registramos la riqueza de aves de Poza Rica, una ciudad industrial, y cotejamos la categoría de conservación (nacional e internacional) y de residencia de las especies. De 2014 a 2017 realizamos una búsqueda intensiva no sistemática de aves con recorridos ad libitum en diferentes sitios del paisaje urbano. Registramos 64 especies (de 13 órdenes y 27 familias). Cuatro especies (Buteo swainsoni, Cairina moschata, Falco femoralis y Psarocolius montezuma) están protegidas por la legislación nacional. La riqueza de aves en Poza Rica fue relativamente baja, y es muy probable que sea por las condiciones industrializadas de la ciudad y su extensión. Por último, resaltamos que las zonas urbanas, aun siendo pequeñas, sirven como resguardo de especies protegidas y pueden ser espacios donde las personas observen, interactúen y protejan a las aves silvestres.

Persistent organic pollutants in eggs from south Texas Aplomado falcons.

A program to reintroduce the Northern Aplomado falcon (Falco femoralis septentrionalis) in south Texas and the southwestern United States was initiated in the late 1970s. Fledgling Aplomado falcons were first released in the Laguna Atascosa National Wildlife Refuge in 1993 and the first nesting pair in the area was recorded by 1995. During 2004-2017 we collected addled eggs from nesting pairs in the Laguna Atascosa National Wildlife Refuge and Matagorda Island in south Texas, to determine if environmental contaminants in Aplomado falcon eggs had decreased over time and if eggshell thickness values were similar to those in the pre-DDT era. We analyzed organochlorine pesticides, PCBs, and PBDEs in 60 egg homogenates by gas chromatography-mass spectrometry. Eggshells were measured to determine thickness and to correlate with contaminant concentrations. Mean concentration in eggs were 244ng/g ww for p,p'- DDE, 270ng/g ww for PCBs and 10ng/g ww for PBDEs. These values were lower than those reported in a previous study for eggs collected between 1999 and 2003, with a mean of 821ng/g ww for p,p'-DDE and 1228ng/g ww for total PCBs. Eggshell thickness ranged from 0.206mm to 0.320mm (n=156). Overall, contaminant concentrations in eggs of Aplomado falcons were low, at levels not likely to impact the recovery of the species. Data from this and previous studies indicate that DDE has decreased significantly in eggs of Aplomado falcons over the last 25 years in south Texas. Breeding populations have been steady at over 30 breeding pairs in south Texas since 2011, although they decreased to 24 pairs in 2018 following Hurricane Harvey.

Opportunistic predation reveals a hidden cost of fighting in birds

Predation risk is often hypothesized to be a cost of escalated fighting, and it relies on the assumption that predators eavesdrop on distracted prey. However, there is no direct evidence supporting these two ideas. Here, I report a predation event that occurred immediately after escalated fighting in birds. Two Rufous Horneros (Furnarius rufus) were engaged in a contest on the ground, while a third hornero watched from a close by (~ 3 m) perch. The hornero that won the contest, having strongly pecked its opponent, then joined the third hornero on the perch. The loser hornero appeared to be injured or fatigued after fighting and crouched motionless, wings down, and belly touching the ground. Approximately 10 s after the fight, a large Aplomado Falcon (Falco femoralis) suddenly flew toward the loser hornero, caught the bird, and flew away. This casual predation record indicates the falcon was eavesdropping on these horneros’ contest, possibly using the opportunity to attack the loser hornero which, due to being injured or fatigued after the contest, was more vulnerable to predation. This anecdotal evidence indicates the existence of a predation cost associated with escalated fighting, stressing the importance of natural history records in animal behavior research.

Natal Dispersal of Aplomado Falcons in Chihuahua, Mexico

The persistence of a species throughout its geographic range requires dispersal among its populations. The study of dispersal is particularly relevant for species whose geographic range has contracted, such as the endangered Northern Aplomado Falcon (Falco femoralis septentrionalis). We used Argos 5-g PTT-100 satellite transmitters to determine the movements of two wild Chihuahuan Desert Aplomado Falcons (one female and one male) from fledging to breeding (male), or transmitter failure (female), at 1062 d and 439 d of age, respectively. Both falcons dispersed from their natal territories 2–3 mo after fledging. These falcons then wandered between activity centers near historic breeding territories and some territories recently converted to farmlands. These two falcons also explored areas outside known breeding areas via some long-distance movements to areas of potential breeding habitat being converted to farmland. In 2 yr, movements of the male covered 7412 km2. This falcon nested unsuccessfully with an unbanded female in a vacant breeding territory 15 km from his natal site. His nesting attempt the following year yielded two fledglings. While a breeding bird, the male falcon had a home range of 200 km2. For 17 mo, the female falcon wandered through an area of 12,136 km2. The farthest distance she traveled from her nest site prior to transmitter failure was 154 km.

Temporal Genetic Diversity and Effective Population Size of the Reintroduced Aplomado Falcon (Falco femoralis) Population in Coastal South Texas

Temporal Genetic Diversity and Effective Population Size of the Reintroduced Aplomado Falcon (Falco femoralis) Population in Coastal South Texas

Nesting biology of the Aplomado Falcon (Falco femoralis) at Parque Nacional das Emas, central Brazil

Te objective of this study was to investigate aspects of the nesting biology of the Aplomado Falcon, Falco femoralis (Temminck, 1822), at Parque Nacional das Emas, Brazil. Woodland (Campo Cerrado) frebreaks were searched for nests in October 2006 and October 2009 by driving a vehicle along a road adjacent to these fre managed vegetation strips. Most (62%) of the eight nests found were in canopies of fruiting Pouteria torta trees. Nests were at 2.2–3.8 m above ground. Invariably, clutch size was of three cream eggs and nestlings had a white plumage in the frst days of life. For two active nests, adults also defended an additional empty nest located in the surroundings. No evidences of nest destruction or predation were detected. Falco femoralis successfully uses frebreaks for breeding at Parque Nacional das Emas.

The history of Aplomado Falcon Falco femoralis subspecies diagnoses

I present the historical details associated with early 20th century descriptions of Aplomado Falcon subspecies. I identify potential weaknesses in these diagnoses that justify re-examination of traditional taxonomy, and stress that climate change, habitat modification and large-scale reintroduction efforts may have altered or eliminated any valid subspecies boundaries that once existed. I recommend that conservation efforts in the Northern Hemisphere focus on the Chihuahuan Desert of Mexico where Aplomado Falcons have declined severely in recent years.

Coastal Prairie Recovery in Response to Shrub Removal Method and Degree of Shrub Encroachment

Shrub encroachment into grasslands is a worldwide phenomenon with no signs of abating and numerous ecological consequences. In South Texas, honey mesquite (Prosopis glandulosa Torr.) and huisache (Vachellia farnesiana [L.] Wight & Arn.) are two shrubs encroaching into coastal prairies, reducing cover of the dominant native grass, gulf cordgrass (Spartina spartinae [Trin.] Merr. ex Hitchc.), and decreasing habitat for the endangered Aplomado Falcon (Falco femoralis), which requires grasslands or savannas for survival. To determine the best management approach for deterring shrub encroachment and restoring native grasslands, the US Fish and Wildlife Service used several shrub removal techniques within coastal prairies of the Bahía Grande Wetland Complex of the Laguna Atascosa National Wildlife Refuge, a core site for Aplomado Falcon reintroductions. Here, we assess native grass recovery over a 2-yr period in response to these shrub removal methods (mechanical plus prescribed fire and/or herbicide treatments) and degree of shrub encroachment before treatment. In general, areas with high levels of shrub encroachment before treatment had the highest amount of bare ground and lowest grass cover immediately following an initial mechanical treatment; this legacy effect persisted throughout the study irrespective of shrub removal treatment. Regardless of degree of shrub encroachment before treatment, grasses in areas treated with either mechanical or mechanical followed by herbicide methods recovered the slowest, likely due to residual woody material that hindered seed germination. Herbicide treatment following mechanical removal or mechanical removal plus fire effectively hindered shrub regrowth. Overall, mechanical treatment followed by prescribed fire and then herbicide application most effectively promoted grass recovery while hindering shrub regrowth. These findings suggest that grassland recovery following shrub encroachment into South Texas coastal prairies may be promoted through the application of shrub removal methods that combine mechanical, fire, and herbicide treatments.

SOIL CONTAMINANT SAMPLING RESULTS FROM LOWER RIO GRANDE VALLEY NATIONAL WILDLIFE REFUGE'S BOCA CHICA TRACT, CAMERON COUNTY, TEXAS

SOIL CONTAMINANT SAMPLING RESULTS FROM LOWER RIO GRANDE VALLEY NATIONAL WILDLIFE REFUGE'S BOCA CHICA TRACT, CAMERON COUNTY, TEXAS

Assessing the importance of artificial nest‐sites in the population dynamics of endangered Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas using stochastic simulation models

Habitat availability might be the most important determinant of success for a species reintroduction programme, making investigation of the quality and quantity of habitat needed to produce self‐sustaining populations a research priority for reintroduction ecologists. We used a stochastic model of population dynamics to predict whether attempts to improve existing breeding territories using artificial nest platforms improved the population growth rate and persistence of a reintroduced population of Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas. We further assessed whether the creation of new territories, i.e. conversion of entire areas to suitable habitat and not simply the erection of nest platforms, would lead to a subsequent increase in the nesting population. Our model was able to reproduce several characteristics of the wild population and predicted the number of breeding pairs per year strikingly well (R2 = 0.97). Simulations revealed that the addition of nest platforms improved productivity such that the population would decline to extinction without them but is stable since their installation. Moreover, the model predicted that the increase in productivity due to nest platforms would cause the population to saturate available breeding territories, at which point the population would contain a moderate proportion of non‐territorial birds that could occupy territories if new ones become available. Population size would therefore be proportional to the increase in available territories. Our study demonstrates that artificial nest‐sites can be an effective tool for the management of reintroduced species.

Spatial size dimorphism in New Zealand's last endemic raptor, the Kārearea Falco novaeseelandiae, coincides with a narrow sea strait

Although New Zealand's avifauna includes many unusual birds, species‐level diversity within lineages is typically low. There are, however, several instances where different allied forms are recognized in each of the two main islands. Among them is the Kārearea Falco novaeseelandiae, which is the only surviving endemic raptor species in New Zealand. Recent analysis confirms it to be a distinct lineage in the global radiation of this genus and most closely related to the Aplomado Falcon Falco femoralis of South America. We examined body size metrics and neutral genetic markers in Kārearea sampled across New Zealand to assess subspecific variation within the species. We found strong evidence using linear modelling and Bayesian clustering for two distinct sizes within Kārearea, in addition to the recognized sexual dimorphism. The boundary between the size clusters coincides closely with the Cook Strait, a narrow seaway between the two largest islands. However, analysis of mitochondrial sequence data and nuclear microsatellites showed no compelling partitioning at neutral loci. These data suggest adaptive change along a stepped environmental cline. Lineage splitting in Kārearea has either yet to become apparent in the distribution of neutral genetic variation and/or regional adaptation is proceeding despite gene flow.

The Imminent Disappearance of the Aplomado Falcon from the Chihuahuan Desert

Desaparicion Inminente de Falco femoralis Del Desierto Chihuahuense Seguimos la ocupacion territorial de Falco femoralis durante un periodo de 12 anos (2003–2014) en el centro de Chihuahua, Mexico, bajo condiciones de sequia severa y destruccion de su habitat de anidamiento. La conversion de los territorios de cria de los halcones a tierras agricolas ha destruido hasta ahora 17 de los 35 territorios de cria ocupados por parejas de F. femoralis conocidos al menos una vez desde el ano 2000. Solo una pequena fraccion territorio de los restantes fue ocupada en 2014. La desaparicion de los halcones de los territorios de cria antiguos que se mantienen intactos sugiere un deficit de reclutamiento causado por tasas reproductivas bajas relacionadas con una disminucion general en la calidad de los pastizales y en la cantidad de presas. La persistencia de unas pocas parejas sugiere que la poblacion se mantiene actualmente por la elevada supervivencia de los adultos mas que por su fertilidad. Esta tendencia, asi como...

The Effect of Supplemental Feeding on the Known Survival of Reintroduced Aplomado Falcons: Implications for Recovery

Abstract The northern Aplomado Falcon (Falco femoralis septentrionalis) inhabited the inland and coastal grasslands of Texas, New Mexico, and Arizona until about 1930, when records of aplomados in the United States decreased. In 1986, the species was classified as endangered under the Endangered Species Act. Among other recovery efforts, 102 birds were released from 2006 through 2011, in its former range in New Mexico at the Armendaris Ranch in the south–central portion of the state. To promote their survival, an extended supplemental feeding program was conducted. From 2006 through 2008, supplemental food was provided daily, whereas from 2009 through 2011 food was provided every other day. Providing food once daily corresponded with an increase in the known survival of the aplomados, where known survival was obtained from the recorded observations of falcons at feedings, and the establishment of nearby nesting pairs. Unfortunately, this increase in known short-term survival and reproduction did not seem ...

Rapid expansion of croplands in Chihuahua, Mexico threatens declining North American grassland bird species

Grasslands are one of the most imperiled ecosystems worldwide. Conversion to cropland and desertification, including shrub encroachment, are primary factors behind the loss of temperate grasslands across the globe. Governments and conservation organizations in North America have identified the highest priority grasslands from Canada to Mexico in an effort to conserve grassland biodiversity, particularly migratory birds. Twenty-nine of 33 (88%) grassland-obligate bird species breeding in western North America’s Great Plains are migratory and 90% of these overwinter in the Chihuahuan Desert. The 2.7Mha Valles Centrales is a region of northern Mexico comprised of desert shrublands, mountains and grassland valleys. It supports wintering populations of 28 migratory grassland bird species from the Great Plains, in addition to threatened and endangered species in Mexico such as Aplomado Falcon (Falco femoralis), Pronghorn (Antilocapra americana mexicana) and others. Using remote sensing, we documented a 6.04% annual rate of cropland expansion in the Valles Centrales from 2006 to 2011, resulting in a loss of 69,240ha of valley-bottom grasslands and shrub lands. Open grasslands are the principle habitat for most declining, grassland-obligate bird species. Expansion of center-pivot irrigated cropland was the primary driver of grassland loss. The area cleared for agriculture, as determined via remote sensing, exceeded the amount of land that had been permitted for land-use change to cropland, according to government records, by >2000%. As a consequence of this habitat loss, we estimate the winter carrying capacity for 28 species of grassland birds in this region has been reduced by approximately 355,142 individual birds. At the current rate, the ongoing expansion of ground-water irrigated cropland could eliminate the remaining low-slope valley bottom grasslands from the Valles Centrales region by 2025. Cumulative grassland losses in the Chihuahuan Desert could have severe impacts on global populations of declining migratory grassland birds, as well as several threatened and endangered species. Our findings demand an urgent call to action by governments and responsible resource management agencies to work with the agricultural sectors to address land use change, sustainable agriculture and grassland ecosystem services in this globally-important region for grassland birds and biodiversity.