Breeding biology of the Black Vulture Coragyps atratus brasiliensis (Aves: Cathartidae) in São Paulo, Brazil, with cryptic aspects revealed by camera trapsABSTRACT
Vultures are the only obligate terrestrial scavenging vertebrates, playing critical roles in sanitation and ecosystem services. However, the breeding biology of New World vultures remains poorly understood. Although the Black Vulture Coragyps atratus (Bechstein, 1793) is widely distributed and comprises three subspecies, reproductive aspects are documented primarily for C. a. atratus from North America and C. a. foetens (Lichtenstein, 1817) from Argentina. Here, we investigated the reproduction of a C. a. brasiliensis (Bonaparte, 1850) population in São Paulo state, Brazil. Clutch initiation occurred from June to October, and nestlings were observed until January. Except for a single-egg clutch, all clutches consisted of two eggs or nestlings. All nests were located on the ground, with 11 in anthropogenic structures and four in forest fragments. At one nest, the incubation period was 38 days, and the nestling period was 78 days. Nest survival probability was only 2.7% (423 nest-days and 13 nest losses). Using camera traps, we identified causes of nest failure-including flooding, predation by domestic dogs Canis lupus familiaris Linnaeus, 1758, and the second confirmed case of intraspecific nest predation for the species. Camera traps also revealed unprecedented behaviors for New World vultures, such as nocturnal nestling provisioning and parent-offspring necrophagy. Because this species occurs in a variety of habitats, our data are valuable for investigating whether certain environments act as ecological traps for this ecologically vital bird.
KEYWORDS:
Intraspecific nest predation; nocturnal nestling provisioning; parent-offspring necrophagy; scavengers
INTRODUCTION
Vultures are the only obligate scavenging terrestrial vertebrates (Ruxton and Houston 2004, Ogada et al. 2012), and their adaptations to locate carcasses and feed on carrion include soaring flight, keen eyesight, high olfactory capacity, and a very low gastric pH (Ruxton and Houston 2004). Due to their scavenging habits, vultures accelerate carcass decomposition, which increases energy flow and reduces the potential transmission of diseases from dead animals to wildlife, livestock, and humans, thereby providing key ecosystem services (DeVault et al. 2003, Ogada et al. 2012). The order Cathartiformes is represented exclusively by the family Cathartidae, which comprises five genera and seven species distributed throughout many habitat types from extreme South America to southern Canada (Winkler et al. 2020). Although the ecological functions played by these birds and the loss of ecosystem services due to population declines have been of scientific interest for decades (Ruxton and Houston 2004, Ogada et al. 2012), the reproductive aspects of New World vultures remain poorly understood (DeVault et al. 2003, Monsalvo et al. 2020, Winkler et al. 2020).
The Black Vulture Coragyps atratus (Bechstein, 1793) is the most abundant New World vulture and is subdivided into three subspecies that occur in virtually all habitat types: C. a. atratus (Bechstein, 1793), distributed in the southern USA and northern Mexico; C. a. foetens (Lichtenstein, 1817), which occurs mainly along the Andes and adjacent lowlands in Ecuador, Peru, Bolivia, Argentina, Paraguay, Uruguay, and Chile; and C. a. brasiliensis (Bonaparte, 1850), distributed from central Mexico to southern Brazil (Buckley et al. 2022). Clutches consist mostly of two eggs laid directly on the ground, in tree cavities, rocky fissures, or a variety of anthropogenic structures (Baynard 1913, Marchant 1960, Wetmore 1965, Stewart 1974, Jackson 1983, Monsalvo et al. 2020). While the reproductive aspects of the nominal subspecies have been thoroughly investigated in North America, breeding information for the other subspecies remains scarce and scattered.
Because New World vultures are large animals weighing from 1.5 kg [the Turkey Vulture Cathartes aura (Linnaeus, 1758)] to 15 kg [the Andean Condor Vultur gryphus Linnaeus, 1758] (Winkler et al. 2020), motion-triggered devices are highly promising for continuous nest monitoring. Camera traps have proven to be useful tools for identifying nest predators and monitoring parental care in marked Turkey Vultures in Canada (Rollack et al. 2013) and Hooded Vultures Necrosyrtes monachus (Temminck, 1823) in South Africa (Thompson et al. 2017, Fern et al. 2022). These devices also permitted assessing the effects of temperature on nest attendance by the colonially nesting Cape Vulture Gyps coprotheres (Forster, 1798) in South Africa (Freitas et al. 2025).
Here, we investigate the reproductive biology of the Black Vulture in southeastern Brazil. We address the reproductive phenology, nest sites, clutch size, egg characteristics, incubation and nestling period durations, and nest survival for a population of C. a. brasiliensis in São Paulo state. By installing camera traps at target nests, we also aim to identify the causes of nest failure and evaluate the effectiveness of these devices for recording parental activities.
MATERIAL AND METHODS
Study area
We conducted our study at the campus of Universidade Federal de São Carlos, in the city of Sorocaba, state of São Paulo, southeastern Brazil (23°34’41”S; 47°31’48”W). The 70-ha campus includes approximately 5 ha of urbanized areas. The non-urbanized areas comprise a ~1.5-ha fragment of arboreal Cerrado (Cerradão) in a late regeneration stage, five secondary patches of semideciduous Atlantic Forest (2-3 ha each) connected by a system of secondary forest corridors, and a predominant matrix of abandoned pastureland dominated by exotic grasses (about 40 ha). According to the Köppen climate classification, the area is categorized as Cwa (characterized by a hot, humid season from October through March and a cold, dry season from April through September). Average annual rainfall is 1,311 mm, and the average annual temperature is 22 °C (Dubreuil et al. 2019).
Field procedures
Over a two-year period (April 2023 to March 2025), we searched for nests using ad libitum sampling during biweekly surveys across all campus environments. We located nests by thoroughly inspecting sites where pairs exhibited persistent fidelity and by observing sites where Black Vultures were flushed by our approach. Egg shape was classified following Winkler (2004); eggs were measured with a metal caliper (to the nearest 0.1 mm) and weighed with a spring scale (to the nearest 1 g; Pesola Inc.). Nests were checked every three to four days to monitor survival, with observation frequency increased to daily monitoring near the laying, hatching, and fledging stages to precisely determine incubation and nestling periods.
The incubation period was defined as the interval from the first day of incubation to the hatching of the first egg, and the nestling period from hatching to the fledging of the last nestling. Because the few nests where clutch initiation was observed were located within university buildings (see Results), we could check them several times a day to confirm the onset of incubation. The month of clutch initiation was back-calculated from the hatching date or the developmental stage of the nestlings, following McHargue (1981).
Whenever possible, nests were monitored using an infrared camera trap (Bushnell TrophyCam, model 119437C, Bushnell Outdoor Products, Kansas, USA), mounted on either existing structures or tripods. Cameras were programmed to record 30-s videos with low LED intensity, “High” sensor sensitivity, a 3-s trigger interval, and time/date stamps, following optimization procedures by Ribeiro-Silva et al. (2018). All cameras were positioned at least 2 m from the nests. Video data were used to: (1) identify potential nest predators and (2) assess parental care. Specifically, we attempted to identify individuals based on the unique facial and neck skin wrinkle patterns to investigate sex-specific roles in egg incubation and nestling provisioning.
Data analyses
Because nests depredated in early incubation stages have a lower probability of detection, apparent nesting success can overestimate nest survival probability. Therefore, we estimated nest survival using the Mayfield (1961) method, which is based on Daily Survival Rates (DSR). The DSR is calculated by dividing the number of nest losses by the total monitoring days accumulated across all nests (nest-days), and subtracting this value from 1. The overall probability of nest survival is obtained by raising the DSR to the power of the nesting cycle length (incubation plus nestling period). Nests were considered successful when at least one nestling fledged. For comparative purposes, we also calculated apparent nest survival (the percentage of nests that produced at least one fledgling). Descriptive statistics are presented as mean followed by Standard Deviation (± SD).
RESULTS
Breeding phenology and nest sites
Over the two-year study period, we recorded a total of 15 clutches. Based on Julian dates, the earliest nest was found on 26 June 2024 containing two eggs, and the latest breeding activity was recorded on 13 January 2025, when a young fledged successfully. The latest eggs, however, were observed much earlier, on 12 November 2024, with clutch initiations spanning from June to October (five months; Fig. 1). All nests were located on the ground (including those within buildings), with eggs laid directly on the soil, leaf litter, or pebbles; a few nests exhibited small amounts of dry leaves as lining material (Table 1, Fig. 2). Of the 15 clutches, 11 were placed within anthropogenic structures and four within forested areas (Table 1). Among the anthropogenic structures, five clutches were found inside two abandoned culverts located in the non-urbanized areas of the campus (Fig. 2A). These culverts were disconnected from the drainage system, meaning that water never flowed through them. Three of these clutches were deposited in the sand at the culvert entrance compartment, 1.5 m below ground level (Fig. 2B), whereas in two instances the vultures entered deep (~2.5 m) into the horizontal tubes connected to the bottom of the culverts to lay their eggs (Fig. 2C, Table 1).
Distribution of active nests (those containing eggs or nestlings) in gray, and of clutch initiations (black) of the black vulture Coragyps atratus brasiliensis across months in an area from southeastern Brazil.
(A) Abandoned culvert used by black vultures for nidification; (B) black vulture nest placed within the entrance compartment of a culvert, 1.5 m below ground; (C) nest placed 2.5 deep inside a tube placed within a culvert; (D) a nest constructed in a vegetated area in the middle of a dense agglomerate of spiny gravatás Bromelia antiacantha.
Dates in which 15 clutches of the black vulture were found in São Paulo state, Brazil, and descriptions of the substrates in which eggs were laid (Substrate), nest site, and nest location. Because nestling start moving around early, substrates were not provided for nests found with nestlings (clutches 4 and 5).
Six clutches were located within five different buildings: four in roofed areas and two in an indoor garden exposed to rain (Table 1). Two of these buildings were abandoned structures in non-urbanized areas, but the remaining three had constant human traffic. The four clutches found in non-anthropogenic structures were located within narrow (~4-m wide) forest vegetation corridors embedded within the pastureland matrix. These nests were positioned close to tree roots or placed in the middle of dense aggregations of the spiny gravatás Bromelia antiacantha Bertol. (Bromeliaceae) (Fig. 2D, Table 1).
Three nest sites were reused across the study years, and one nest site was reused for a replacement clutch laid within the same breeding season (52 days later). Second clutches were laid either in the exact same location (two nests) or 2.5 to 3.0 m away from the first clutch site. Except for one instance where a nest site was reused after a successful clutch was raised the previous year, all other cases involved the reuse of sites where the first clutch had failed. Assuming these sites were reused by the same breeding pairs, our observations likely represent clutches from no more than 11 distinct pairs.
Clutch and egg characteristics, incubation, and parental care
Except for a single-egg clutch, the remaining 14 clutches consisted of two eggs or nestlings when discovered. Eggs varied in shape, tending toward oval, pyriform, or ellipsoid (Fig. 3), and measured 7.5-8.2 cm (mean: 7.9 ± 0.3 SD) in length, 4.9-5.1 cm (4.9 ± 0.1 SD) in width, and weighed 108-114 g (110 ± 2.9 SD; n = 4 eggs from two clutches). The eggshell background color was white, but progressively became brownish over time due to soil staining, particularly in locations exposed to rain. While some eggs were virtually immaculate, others were densely marked with predominantly sepia-brown blotches, dots, and streaks concentrated at or forming a crown around the larger end (Fig. 3); these variations occurred even within the same clutch.
In two nests monitored from the laying stage, eggs were laid on consecutive days in one nest and with a 48-hours interval in the other. In the former, incubation began on the day the second egg was laid, whereas in the latter, incubation started approximately 48 hours after the second egg was laid. In one two-egg nest, the incubation period for one egg was 38 days, while the other egg failed to hatch. The nestling period for this single young was 78 days. Notably, one clutch containing unhatched eggs was incubated for 72 days before the eggs were broken.
Three nests were monitored with camera traps during the incubation stage for 7, 5, and 12 days (totaling 24 days), and four nests were monitored during the nestling stage for 3, 5, 2, and 22 days (totaling 32 days). Video quality did not permit the differentiation of parental individuals based on skin folds. For the incubation period, despite recording more than 2,400 videos, we could not confirm parental sharing (e.g., by capturing both individuals during incubation shifts).
For the nestling stage, we obtained 46 videos of nestling provisioning. Adults most frequently regurgitated food directly into the beaks of the nestlings, even when they neared fledging age (Video S1); on only three occasions did adults regurgitate food onto the ground. Thirty nestling provisioning events occurred during the day, and 16 were nocturnal (1:04 a.m., 1:05 a.m., 1:25 a.m., 1:19 a.m., 2:23 a.m., 4:08 a.m., 4:40 a.m., 11:23 p.m., 1:51 a.m., 8:15 p.m., 8:47 p.m., 8:14 p.m., 9:12 p.m., 9:41 p.m., 1:33 a.m., 10:59 p.m.) (Video S2), with nocturnal provisioning recorded across all four nests monitored during the nestling stage. On one occasion, both parents fed the young concomitantly, indicating shared provisioning duties. In two nests where fledging was observed, the young returned to the nest the following day to be fed by a parent, after which they abandoned the nest site permanently.
During ad libitum observations, we recorded courtship or mate feeding three times, where one adult (presumably the male) fed the other by regurgitating food directly into its beak; in all instances, the attending adult left the nest to be fed 10 to 60 m away from the nest site. In one nest, one of the two hatchlings was found dead on the day a camera was installed at 4:00 p.m. During the night, the adult attempted to stimulate the dead nestling at least 14 times and regularly brooded it alongside the surviving sibling (Video S3). The following morning, at 7:30 a.m., the adult moved both nestlings approximately 1 m away, and at 9:57 a.m., it began to consume the dead nestling (Video S4).
Nest survival and causes of failure
Only two of the 15 clutches survived to fledging (apparent nest success: 13.3%). Six clutches were depredated during the incubation stage, four were depredated during the nestling stage, one nest was lost to flooding, one was abandoned during incubation, and one contained unhatched eggs. In the nest lost to flooding, the adult continued incubating during a heavy rain event, even when the eggs and part of its body were completely submerged (Video S5); the eggs were abandoned only 25 days later.
The Mayfield nest survival probability was 2.7% (based on 423 nest-days, 13 nest losses, and a 116-day nesting cycle). Three predation events were captured by camera traps: a nest with two approximately one-week-old nestlings was depredated by domestic dogs Canis lupus familiaris Linnaeus, 1758 (Video S6); a two-egg nest was depredated by a tegu Salvator merianae Duméril & Bibron, 1839 (Video S7); and a single-egg nest was depredated by another Black Vulture (Videos S8 and S9). Additionally, a white-eared opossum Didelphis albiventris Lund, 1840 was recorded consuming nestling carcasses immediately after they were killed by domestic dogs, indicating this species is a potential opportunistic nest predator.
DISCUSSION
Our study is the first to monitor nests of C. a. brasiliensis across all months of the year in Brazil, significantly improving the understanding of the species’ breeding phenology. A comprehensive review of the reproduction of New World vultures nesting in the Neotropics was provided by Monsalvo et al. (2020), who documented that nesting records of C. a. brasiliensis occurred throughout the year. However, their data were compiled across a vast latitudinal range-from the Amazon to southern Brazil-encompassing regions with highly contrasting weather regimes. For this reason, those authors did not discard the possibility that shorter, localized breeding seasons could occur at specific locations (Monsalvo et al. 2020), a hypothesis confirmed by our data.
Although active nests were found from June to January (eight months) in our study area, egg-laying occurred exclusively from June to October (five months). The extension of the breeding season into January was due to a single nest where laying occurred late in the season, and the nestling successfully survived to fledging age. This seasonal pattern matches the information obtained for C. a. foetens at similar latitudes in Argentina, where active nests were found from July to December (six months) (Di Giacomo 2005). Conversely, in Panama, active nests of C. a. brasiliensis were reported from October to March by McHargue (1981) and from January to May by Wetmore (1965). In Ecuador, C. a. foetens nested from February to June (Marchant 1960). Together, these datasets reveal that both C. a. brasiliensis and C. a. foetens exhibit latitudinal adjustments in their breeding phenologies across the Neotropical region.
For C. a. atratus, detailed monitoring of a single nest in Virginia, USA, showed that eggs were laid on consecutive days (Stewart 1974), while in Florida, USA, Baynard (1909) reported eggs being laid either on consecutive days (n = 6 nests), or with intervals of one day (n = 11) or three days (n = 4). Here, we confirmed that laying patterns can vary across broods for C. a. brasiliensis as well, with eggs laid on consecutive days or with a 48-hours gap.
Determining the incubation and nestling periods for New World vultures, however, remains a logistical challenge. Obtaining precise incubation periods is difficult because cathartids virtually do not construct nests. This hinders nest discovery before or during the egg-laying stage, which in other bird groups is facilitated by monitoring adults carrying nesting materials (Martin and Geupel 1993). Furthermore, we observed that incubation does not always start on the day of clutch completion, which may lead to flawed estimates in broader studies.
For the nestling period, defining the exact fledging day is complicated because nestlings begin walking around the nest surroundings when they are only a few days old (McHargue 1981), and they start to perch on adjacent structures weeks before successfully flying away from the nest site. In sheltered nest sites, for instance, nestlings may take even longer to develop the flight capabilities required for fledging. In one of our monitored culverts, where the entrance was partially obstructed by a concrete lid, the nestlings remained for at least two weeks after their plumage was completely developed before being able to fly through the narrow passage; our cameras recorded numerous unsuccessful fledging attempts. Although this nest could not be observed from the hatching stage, the fledging of these young was likely delayed. Therefore, while the high variation evidenced in the literature for Black Vulture nestling periods is expected, variations in reported incubation periods have likely been caused by incomplete observations or the use of disparate estimation methods that go undescribed in the literature. Although our nesting cycle duration data are based on only a single nest, the intrinsic difficulties of monitoring this species render this the only precise information on the nesting cycle for C. a. brasilensis in Brazil.
The incubation period recorded in this study (38 days) matches that reported for C. a. brasiliensis in Panama (McHargue 1981) and C. a. atratus in Virginia (Stewart 1974). However, it was shorter than the 41 days reported for Texas, USA (Shaffer et al. 2022) and the 39-41 days reported for C. a. foetens in Argentina (Di Giacomo 2005). The period of 28-30 days reported by Baynard (1909) for Florida was likely underestimated. The single nest for which we observed the entire nesting cycle was located on the ground within an indoor garden of a roofed building. Although the nestling started perching on suspended structures at 43 days of age, we defined fledging as the day it left the interior of the building and flew to the roof. Our nestling period estimate of 78 days falls within the range reported in the literature: 81-83 and at least 90 days in Panama (C. a. brasiliensis; McHargue 1981); 87 days in Virginia (C. a. atratus; Stewart 1974); approximately 98 days in Florida (Baynard 1913); 73-74 days in Texas (Shaffer et al. 2022); and 74-81 days for C. a. foetens in Argentina (Di Giacomo 2005).
Black Vultures have been frequently recorded consuming conspecific carcasses (McGehee et al. 2008, Evans et al. 2022), and a group of C. a. atratus in Florida was recently filmed killing and consuming a flightless conspecific juvenile, confirming cannibalism in this species (Evans et al. 2022). Because Black Vultures also depredate the eggs and nestlings of other birds (Menezes and Marini 2017), and conspecifics are regularly observed visiting Turkey Vulture nests (Rollack et al. 2013), our records of intraspecific nest predation and parent-offspring necrophagy were somewhat expected. Intraspecific egg destruction was first recorded for C. a. atratus in Mississippi, USA, inside a concrete tunnel of a riverine pier (Rush and Naveda-Rodríguez 2024). Our findings suggest that this behavior may be widespread across Black Vulture populations.
Rush and Naveda-Rodríguez (2024) suggested that because Black Vulture abundance has increased alongside the colonization of anthropogenic ecosystems, competition for suitable nesting sites drives intraspecific nest destruction. In our study, however, this explanation seems unlikely because the intraspecific predation event occurred in a nest positioned directly on the ground within a natural forest fragment. Furthermore, unlike the observations of Rush and Naveda-Rodríguez (2024), we filmed the conspecific predator actively consuming the egg contents, indicating a search for an energetic reward. Therefore, the hypothesis that intraspecific predation occurs due to localized food scarcity appears more plausible (see Evans et al. 2022).
The apparent nest survival of 13.3% and the Mayfield (1961) nest survival probability of 2.7% observed in our study population are remarkably low. In at least three independent studies of C. a. atratus in North America, apparent nest survival was 76.5% (n = 98 nests; Rabenold and Decker 1990), 59% (n = 49; Jackson 1983), and 91.7% (n = 12; F.R. Gehlbach in Buckley et al. 2022). Furthermore, apparent nest survival for the Turkey Vulture was 67.4% (n = 46) in Ontario, Canada (Peck 2003) and 79.2% (n = 19) in Illinois, USA (Buhnerkempe and Westemeier 1983). Our low survival estimates are comparable only to a Black Vulture population from Ecuador (likely C. a. foetens), where apparent nest survival was 17.6% (n = 17) (Marchant 1960).
Black Vultures are characterized by high nest-site plasticity (Monsalvo et al. 2020), and our data demonstrate that this plasticity is even broader than previously described, as birds in our study area utilized underground structures (see Monsalvo et al. 2020 for a thorough review on nest sites). Underground nesting was first recorded by Marchant (1960), who observed 13 nests in Ecuadorian drainage systems that he described as “semi-underground” structures, as well as one nest inside a 3-m deep vertical pit. Although underground nesting has not been reported since Marchant (1960), we confirmed that it can represent a common pattern in certain populations, as four of our 15 recorded clutches were located deep within culverts.
Notably, all nests found in our study were located on the ground, including those inside anthropogenic structures. Except for a single nest, all nests observed by Marchant (1960) were also on the ground; notably, these two populations exhibit the lowest nest survival percentages reported for the species. Most nests from other studied populations were located on suspended structures, including the upper levels of buildings. In the broad dataset analyzed by Jackson (1983), for instance, at least 30% of nests were located in tree hollows and caves, while Rabenold and Decker (1990) found higher nesting success in abandoned buildings far from human settlements. In our study area, large tree cavities, rocky cliffs, and well-protected tall anthropogenic structures such as skyscrapers (Hill and Scherer-Neto 1991) were unavailable.
In North America, the Red Fox Vulpes vulpes (Linnaeus, 1758), domestic dogs, the American Crow Corvus brachyrhynchos Brehm, 1822, and the Virginia Opossum Didelphis virginiana (Kerr, 1792) have been listed as potential predators of Black Vulture nests (Coleman and Fraser 1986). Here, we confirmed the predatory action of domestic dogs and the White-eared Opossum, and identified the Tegu Salvator merianae as another terrestrial predator. Tegus are highly common lizards in both natural and anthropogenic habitats and are among the most frequent nest predators in Neotropical avian communities, particularly for ground-nesting species (Lobo-Araújo et al. 2024). Nest flooding, which was also recorded by Marchant (1960) for two ground nests in Ecuador, represents another severe risk that is naturally mitigated in suspended nesting sites.
It is also worth noting that four nest sites were reused within or between seasons. Three of them were reused after the first clutch failed, and all subsequent replacement clutches were depredated. This contradicts the widespread avian behavior of avoiding the reuse of nesting sites that have proven unsafe (Haas 1998, Styrsky 2005). Nest-site reuse is a common behavior among New World vultures (McHargue 1981, Rabenold 1986), and the scarcity of suitable, sheltered locations in our study area could explain this persistence. However, habitat limitation may not be the sole driver, as one of these reused sites was located on the ground within a forest patch. For C. a. brasiliensis in Panama, active nests were found during five consecutive years at distances varying by only 1-3 m, strongly suggesting multi-year site fidelity by the same pair (McHargue 1981). We suggest that future studies investigate site fidelity as a potential parameter accounting for the low reproductive success observed here. Although the Black Vulture is not globally threatened, future research should address whether the compulsion to nest directly on the ground in habitats lacking suspended structures creates an ecological trap for this species.
Although camera traps were not effective for the rigorous quantification of parental care allocation, they proved invaluable for detecting elusive behaviors previously undescribed for the Cathartidae, such as parent-offspring necrophagy and nocturnal nestling provisioning. The parent-offspring necrophagy we observed involved an early-stage nestling that died of unknown causes. An adult attended to the dead nestling for at least 18 hours-brooding and moving it alongside the surviving chick-suggesting that the parent did not killed its own offspring. Only on the following day did the adult begin to consume pieces of flesh from the dead nestling, representing the first formal record of this behavior for the species. This behavior differs fundamentally from the typical filicide observed in many Falconiformes, where adults actively kill the weakest offspring to feed healthier siblings during periods of food scarcity (Allen et al. 2021).
Nocturnal nestling provisioning by otherwise diurnal birds has been recorded across distinct avian lineages, including shorebirds (Johnson et al. 2002, Winden 2005), swifts (Gunn 2022), and thrushes (Ball et al. 2011). While in those documented cases the adults typically forage at night to feed their young, the parental Black Vultures in our study did not leave the nest during nocturnal hours. This demonstrates that they store food in their upper digestive tract specifically for nocturnal provisioning. Stewart (1974) hypothesized that Black Vultures might feed nestlings at night based on vocalizations, but the behavior was never directly observed. Here, we confirmed nocturnal provisioning, noting that it occurred exclusively during the early developmental stages of the nestlings. This could potentially maximize growth rates during a critical survival phase, a hypothesis that warrants further investigation. While diurnal avian activity can increase at night in areas exposed to artificial light pollution (Injaian et al. 2021), this was not the case in our study, as three of the four nests exhibiting nocturnal provisioning were located in completely non-urbanized sectors of the campus.
In conclusion, our study contributes critical new data on the breeding biology of C. a. brasiliensis, including a sharply demarked breeding season in southeastern Brazil that contrasts with populations in Panama, the first precise estimates of incubation and nestling durations for the region, the first records of egg mass, the first documented case of intraspecific nest predation, and a remarkably low nest survival rate associated with terrestrial predators such as the Tegu. Furthermore, we present novel behavioral findings for the species, including nocturnal nestling provisioning and parent-offspring necrophagy. Although camera traps were inefficient for partitioning parental care between sexes, they successfully uncovered transient, uncommon behaviors that would rarely be captured by human observers during traditional focal sessions. We reinforce the evidence that continuous recording devices are highly effective tools for nest monitoring, capable of capturing hidden dimensions of animal behavior. Because the Black Vulture presents high ecological plasticity and breeds across a variety of natural and disturbed habitats, our baseline data will serve future comparisons aimed at understanding variations in life-history parameters and reproductive success across different environmental matrices.
ACKNOWLEDGMENTS
The authors are grateful to Alexandre G. Franchin, Augusto J. Piratelli, and two anonymous referees for important suggestions on the previous versions of this article.
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ADDITIONAL NOTES
- ZooBank register
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Data Availability Statement
All data generated and/or analyzed are included in this article.
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Funding
MFS Camilo received an undergraduate fellowship from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (PIBIC/CNPq 142308/2019-6) and MR Francisco received a Productivity Research Fellowship also from CNPq (304213/2022-5)
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Ethical Statement
SISBio/MMA (Procs# 66157-6 and 94799-1) and the Ethic Committee on Animal Use from Universidade Federal de São Carlos (Procs# 1405291118 and 8681230824) authorized field work and approved the methods.
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AI Statement
No artificial intelligence tools were used in the preparation of this manuscript.
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How to cite this article
Silva MC, Camilo MFS, Francisco MR (2026) Breeding biology of the black vulture Coragyps atratus brasiliensis (Aves: Cathartidae) in São Paulo, Brazil, with secretive aspects revealed by camera traps. Zoologia 43: e25048. https://doi.org/10.1590/S1984-4689.v43.e25048
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Published by
Sociedade Brasileira de Zoologia at Scientific Electronic Library Online - https://www.scielo.br/zool
Supplementary materials
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Video S9
Authors: M.C. Silva, M.F.S. Camilo, M.R. Francisco
Data type: Behavioral data
Copyright notice: This dataset is made available under the Open Database License - ODBbL (https://opendatacommons.org/licenses/odbl/1.0/). The ODbL is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
Link: https://doi.org/10.1590/S1984-4689.v43.e25048
All data generated and/or analyzed are included in this article.
