Electrocution is an important threat to many bird species worldwide (Lehman et al., 2007; Kemper et al., 2013; Martín Martín et al., 2022). Amongst birds, raptors are particularly vulnerable to electrocution due to their large body size when compared to other groups, and especially because they spend a considerable amount of time perched while hunting (Dwyer et al., 2015), a behavior that, in areas with low availability of trees or other perches, increases the risk of electrocution (Lehman et al., 2010). For that reason, electrocution in power lines is of particular conservation concern for raptors and it has contributed to the declines of their populations on several continents (Eccleston and Harness, 2018; Slater et al., 2020).

However, and despite the significance of electrocution in power lines for raptor conservation, this anthropogenic source of mortality remains vastly understudied for large regions and across entire continents (Lehman et al., 2007; Guil and Pérez-García, 2022; Rebolo-Ifrán et al., 2023). Specifically, and as happens with other fields of avian research (Buechley et al., 2019, Gallego‐García and Sarasola, 2025), a great part of the southern hemisphere has a generalized scarcity of studies on avian electrocution (Guil and Pérez-García, 2022). In the case of South America, although it contains almost a third of the globally recognized raptor species (Sarasola et al., 2018), most recorded electrocution incidents are largely anecdotal (but see Galmes et al., 2018; Gusmão et al., 2020; Sarasola et al., 2020; Biasotto et al., 2022; Rebolo-Ifrán et al., 2023).

Electrocution of birds at power line poles occurs in two ways: when individuals touch two phases simultaneously, or when they touch one phase and a grounded object. Therefore, avian electrocution probability largely depends on two closely related factors: power line designs and the materials used to build them (Martín Martín et al., 2022). Most avian electrocution occurs at electrical distribution lines of low- to medium-voltage (i.e., 1–60 kV; Lehman et al., 2007) due to narrow clearances between energized and grounded components. Although with scarce reports, avian electrocution from southern South America mainly occurs on three-phase medium-voltage distribution lines (13.2–33 kV), but also on single-phase low-voltage (7.2 kV) lines. These incidents are often linked to poles and crossarms made of conducting materials (e.g., steel-reinforced concrete or metal) and with jumpers above the crossarms (Galmes et al., 2018; Sarasola et al., 2022b), or with lightning rods on single-phase power lines (Capdevielle et al., 2021). However, with fewer than ten scientific studies available to date, less than 10% of the total area of South America has been surveyed for avian electrocution (Guil and Pérez-García, 2022).

Here, we present a large-scale assessment of avian electrocutions across Argentina, aiming 1) to compile and summarize data on the spatial occurrence and species involved in electrocution events in this country, including biogeographic context, and 2) to provide information on the characteristics of the poles associated with such electrocution events. Considering that economic development typically necessitates the expansion of power line networks, and that large remote areas are being electrified lately due to improvements in electrical services (Stern et al., 2019), this information is crucial not only for assessing the current impacts of electrocution on bird species but also to incorporate it into both future and ongoing population conservation efforts and to promote distribution line monitoring programs focused on avian electrocution (Biasotto et al., 2025).

We documented electrocutions involving birds from 2019 to 2025 in Argentina, across the ecoregions of Monte Desert, Espinal, Dry Chaco, Humid Chaco, and Pampas (Fig. 1) (Cabrera, 1976; Busso and Fernández, 2018). These mortality events were opportunistically obtained as part of large-scale research and conservation projects in central and northern Argentina with the endangered Chaco Eagle (Buteogallus coronatus) (see for instance Sarasola et al., 2022a). We gathered information on electrocutions based on (1) our own findings across the study area, and (2) citizen science reports of mortalities made by local inhabitants, birdwatchers, rural workers and landowners, and conservation nongovernmental organizations. In both cases, but particularly for citizen science reports, we used the app Silent Song available at www.silentsong.top.

Fig. 1.

Map of the study area, depicting the electrocution event locations as white dots. Only those provinces where electrocution events took place are labelled, and the ecoregions are colored (see legend).

For each carcass found under a power line pole, the electrocution event was determined by external examination of the body or provided pictures, based on the presence of burns on the feathers and skin (Kagan, 2016), and georeferenced. We registered the date (and then classified it by season), identified the electrocuted birds to the species level and categorized them by age (immature or adult) based on plumage characteristics and using field identification guides (Narosky and Izurieta, 2011). For each electrocution record, we identified the pole involved and classified it according to its structural characteristics, including the design and material of the poles and crossarms, following Galmes et al. (2018) and Sarasola et al. (2020, 2022b). Poles were described based on the number of phases or cables, the presence and number of jumper wires (short cables that connect stretches of lines) above the crossarms, and the material of both crossarms and poles (steel-reinforced concrete, metal or wood). We also added information on the presence or absence of additional grounding materials such as lightning rods (Capdevielle et al., 2021), and of mitigation measures to avoid bird electrocution such as the insulation of wires (Chevallier et al., 2015).

Data on voltage for each power line where an electrocution event took place was extracted from the official website of the Argentinian Energy Secretary (Secretaría de Energía, 2025, https://sig.energia.gob.ar/visor/visorsig.php).

We documented a total of 160 electrocuted birds of 18 species, of which 150 individuals of 12 species were raptors (Accipitridae, Cathartidae, Falconidae, Strigidae, Tytonidae) (Table 1). Citizen science reports accounted for 63 electrocutions (39.38%), and the rest by our own project assessments. The most affected raptor species were the Black-chested Buzzard-eagle (Geranoaetus melanoleucus, n = 80), the Variable Hawk (G. polyosoma, n = 24), the Black Vulture (Coragyps atratus, n = 13), and the Chaco Eagle (B. coronatus, n = 11) (Table 1). Also, from those birds that could be aged (n = 141), 42.55% were adults and 57.45% were immatures. In most species, the number of immatures and adults electrocuted was similar. The exception was the Black-chested Buzzard-eagle, for which 74.32% of aged individuals were immatures (Table 1). The number of electrocutions per ecoregion was as follows: Monte Desert (n = 72), Espinal (n = 54), Dry Chaco (n = 25), Humid Chaco (n = 7), and Pampas (n = 2). Most electrocutions (n = 110; 68.75%) occurred in winter, followed by spring (n = 33; 20.63%), while very few occurred in autumn (n = 11) and summer (n = 6).

All electrocution events occurred at low-to-medium voltage distribution power lines (7.62 kV = 19 electrocutions; 13.2 kV = 68 electrocutions; 33 kV = 73 electrocutions), and at poles where the phase conductors were above the crossarms, either with wire jumpers or with pin insulators (n = 10 different designs, Table 2). The number of simultaneous electrocutions found per pole ranged from 1 to 6; all multiple mortality events involved Black-chested Buzzard-eagles (n = 16) or Variable Hawks (n = 5), and all but three of these events featured immature individuals. Most electrocution events in three-phase power lines occurred at poles made of concrete (n = 132). The most lethal design was that with a jumper wire over a concrete crossarm (n = 59, Fig. 2A), followed by two designs without the jumper wire, but with pin insulators, one with a concrete crossarm (n = 24, Fig. 2B), and the other with a wooden crossarm (n = 29) (Table 2). We also documented electrocutions in other three-phase combinations of pole-crossarms materials, with and without jumper wires (Table 2). Last, single-phase power lines and all-wood three-phase designs were only deadly when combined with additional grounding materials (e.g., lightning rods) and/or jumper wires (n = 26, Fig. 2C, D) (Table 2). We registered an electrocution event at a pole with a supplemental perch as a mitigation measure; other than that, none of the poles where birds were electrocuted had any mitigation measures implemented (e.g., insulators, retrofitting of phases).

Fig. 2.

Examples of different designs of power line poles where birds were documented electrocuted (Table 1). A = ID 1, three-phase power line, concrete pole and crossarm, and a jumper wire (© Diego Gallego-García); B = ID 2, three-phase power line, concrete pole and crossarm with pin insulators (an immature Chaco eagle, Buteogallus coronatus electrocuted) (© Carlos Robledo); C = ID 8, three-phase power line, wood pole and crossarm with pin insulators, lightning rod on top of the pole (an adult Black-chested Buzzard-eagle, Geranoaetus melanoleucus perched on the crossarm) (© José Hernán Sarasola); D = ID 9, single-phase power line, concrete pole, and a jumper wire (an adult Barn-owl, Tyto alba electrocuted) (© Mauricio Rossanigo). All designs have the wires above the crossarm (Table 2).

This research documented the electrocution of more than a hundred birds in Argentina over six years, most of them being raptors, updating the already large number of dead individuals by this anthropogenic cause of mortality. Additionally, electrocution events occurred all over the study area, mostly at dangerous distribution power line poles according to literature, such as those where the pole and/or the crossarms were made of concrete or metal, and/or those with jumper wires and additional grounding materials above the crossarms.

Our results coincide with previous studies in the Neotropical area, where the Black-chested Buzzard-eagle, the Variable Hawk, the Turkey Vulture (Cathartes aura), and the Black Vulture are recurring and numerous victims of this human-induced source of mortality (Galmes et al., 2018; Biasotto et al., 2022; Rebolo-Ifrán et al., 2023). Although these species are not currently of global conservation concern, electrocution has historically been a major driver of population declines and local extinctions in many raptor populations, regardless of their conservation status (Sergio et al., 2004; Eccleston and Harness, 2018; Slater et al., 2020). Given that records of electrocuted wildlife likely constitute a small fraction of the actual impact caused by power infrastructure, these results should raise concern among energy companies and environmental authorities about the ongoing and potentially large-scale impact on wildlife in this region, where thousands of birds may be electrocuted yearly (Sarasola and Zanón-Martínez, 2017; Sarasola et al., 2022b). Another species that we found electrocuted was the Crested Caracara (Caracara plancus), which may involve an additional risk of electrocution due to the species' habit of building its nests on the crossarms of power lines, due to the contact of the conductive anthropogenic materials (e.g., electric fence ropes, baling twine) of their nests with the energized components of the power line structure (Martínez-Miranzo et al., 2024). Concerning the endangered Chaco Eagle, whose low and declining global population estimates make it highly sensitive to anthropogenic mortality (Sarasola et al., 2022a), these new records confirm that electrocution on power lines constitutes a significant threat to its population (Sarasola et al., 2020). In fact, research up to date adds up to 26 individuals found electrocuted in Argentina (Chebez, 2008, Galmes et al., 2018; Sarasola et al., 2020), constituting an important source of mortality that may exceed other human-related mortality sources such as direct persecution and drowning in water reservoirs (Sarasola et al., 2020, 2022a).

In this country-level assessment, we added six new bird species for which electrocution was overlooked as a cause of mortality: the Great Black Hawk (Buteogallus urubitinga), the Roadside Hawk (Rupornis magnirostris), the Whistling Heron (Syrigma sibilatrix), the Blue-crowned Parakeet (Psittacara acuticaudatus), the Spot-winged Pigeon (Patagioenas maculosa), and the Red-crested Cardinal (Paroaria coronata). Additionally, four raptor species had not been documented electrocuted in Argentina until this study: the American Kestrel (Falco sparverius), the Chimango Caracara (Milvago chimango), the Barn-owl (Tyto furcata), and the Great Horned Owl (Bubo virginianus) (Rebolo-Ifrán et al., 2023). The relevance of electrocution as an important mortality source for birds is again reinforced, as it not only affects large species, but also smaller ones (e.g., American Kestrel) which often may die undetected by researchers (Borner et al., 2017), and even species that do not usually perch at power line pylons, but rather use fence poles and branches to hunt (e.g., Chimango Caracara and Roadside Hawk) (Ferguson-Lees and Christie, 2001; Bierregaard et al., 2024, 2025). Last, this research found that immatures of the Black-chested Buzzard-eagle comprise an important portion of the total mortality (more than one-third of the total number of birds recorded electrocuted), which is probably related to the large aggregations of juveniles that form during dispersal in areas that may have high-risk poles; this might be the main reason why most electrocution events were documented in winter (López et al., 2017; Galmes et al., 2018; Sarasola et al., 2022b). Other raptors whose juveniles may form aggregations (e.g., Variable Hawk – Juhant et al., 2022; Chaco Eagle – Gallego and Sarasola, 2023) did not show this marked pattern.

Despite the opportunistic nature of data gathering, which precludes the possibility of developing detailed spatial analyses, there were more electrocution events at the ecoregions with less overall arboreal cover, and thus with less availability of natural perches (Cabrera, 1976; Busso and Fernández, 2018). The number of records was higher in bush-dominated Monte Desert biome and lower in the dense dry forests of the Espinal and Chaco. The lowest number, however, was recorded for the Pampas region, where native tree species are naturally absent but where large stands of exotic tree species (e.g., Eucalyptus) are widespread and intensively used by raptors for nesting, perching, and roosting (Sarasola and Negro, 2006). However, these results should be contrasted in future research with a standardized study design that will allow specific hypotheses on the effects of the availability of natural perches on the number of electrocutions.

Avian electrocution usually occurs either with a phase-to-phase or phase-to-ground contact. Birds can perch directly on the crossarm, or on top of the pole, and often they have a narrow clearance between themselves and the energized components of the pole (phases, grounded pole, jumper wires and/or lightning rods). In our study, although we demonstrate that nearly all possible designs of poles, crossarms and phases may be risky for birds, some of them are particularly hazardous due to their design and materials. Specifically, the three-phase power line pole and its corresponding crossarm made of concrete, coupled with a jumper wire above it (ID = 1, Table 2), was the most dangerous power line pole design, with more than a third of all documented electrocutions. Furthermore, when considering all the pole designs that have jumper wires above the crossarm, and irrespectively of the crossarm material, this value doubles to reach almost more than half of all the electrocution events. Previous studies in central Argentina concluded that these concrete power line poles with jumper wires, either single- or three-phase, represent less than 2% of the total number of poles in the respective power lines (Galmes et al., 2018; Sarasola et al., 2020). Consequently, to safeguard a large number of birds from electrocutions, energy companies and environmental authorities could start by retrofitting a relatively small number of poles (Sarasola et al., 2020), a convenient first-step process in a scenario of limited funds to later extend the mitigation measurements to all potentially lethal pole configurations (Dwyer and Mannan, 2007; Dwyer et al., 2019). However, not all mitigation measures are equally effective; the documentation of an electrocution event at a power line pole that had a supplemental perch on it should warn energy companies about the obligatoriness of validating any mitigation measures implemented (Sánchez et al., 2020).

Additionally, design combinations where the pole was made of steel-reinforced concrete (ID = 1–6; Table 2) accounted for the majority of the electrocution events, which is consistent with other studies (Eccleston and Harness, 2018; Galmes et al., 2018; Sarasola et al., 2020). The pole made with this conductive material works as a grounding material, so birds only need to touch one of the phases of the crossarm and the pole itself to get electrocuted. Bearing in mind that many wooden power line poles in Argentina are being changed to concrete lately, with their corresponding concrete or steel crossarms (data in preparation by the authors), the impact of these infrastructures on wildlife is prone to aggravate if new designs do not consider other bird-friendly options; for instance, using suspension instead of pin insulators, thus increasing the distance between phases and grounded parts of the poles, or placing jumper wires below the crossarms (Chevallier et al., 2015; Dwyer et al., 2019). Moreover, additional grounding materials used as lightning rods turn formerly safe designs into dangerous ones, as has been shown in other studies, and thus should be removed to reduce bird electrocution risk (Capdevielle et al., 2021). An additional word of caution has to be made with single-phase power line poles that have jumper wires and/or grounding materials. Although single-phase lines constitute a small fraction of the energy distribution network in the country (Secretaría de Energía, 2025), and among them such a pole design being one of the least abundant in the country, they may be comparatively more deadly than others, since the bird is only able to perch on the grounded pole itself, exposing itself to the risk of electrocution if it touches the cable (Sarasola et al., 2020).

This study provides valuable regional-scale information on avian electrocution, including the species affected and the power line pole configurations involved. However, beyond this essential first information, there is much more work to do to effectively reduce the impact of this mortality source for birds in the Neotropics, either by implementing mitigation measures (e.g., retrofitting existing risky poles) or by planning and building new power lines with bird-safety designs and materials. New legislation and the development of specific technical protocols would be helpful in such a transition. Although Argentina's current national (law No. 25675, “Ley General de Ambiente”) and provincial (law No. 3195 of La Pampa, and law No. 11717 of Santa Fe province, for example) environmental legislation does not explicitly address avian electrocution, it already considers the impacts of human infrastructures on wildlife. The reasons why the issue of bird electrocution remains overlooked and why electricity companies are not being penalized by government agencies despite the increasing number of reported cases are probably related to the fact that these companies are also state-owned in Argentina. Therefore, unlike privately owned companies, state environmental agencies actively avoid sanctioning these electricity companies with monetary or criminal penalties, as required by existing legislation.

Under this adverse scenario, it is imperative to promote the continuous monitoring of power lines covering large spatial scales, especially those whose design and/or materials are potentially risky for wildlife, to gain further evidence and adequately assess the demographic impacts of this silent, human-induced source of mortality on bird populations (Sarasola et al., 2020; Biasotto et al., 2025). Furthermore, gathering such overwhelming field evidence on the environmental impacts of power lines will ultimately force government agencies to act against electricity companies, regardless of their private or state ownership status. Currently, only a few legal complaints from third parties (e.g., NGOs, personal accusations) have reached the courts, actions that should be actively encouraged alongside citizen science activities.

For this end, besides local or regional research, we propose a global network of citizen science electrocution reports to fill gaps in species and power line types involved in electrocution events, but also aiming to involve diverse local communities in a practical approach to assess the main factors contributing to the electrocution risk of birds in power lines.