Colonial Nesting Research Articles

An update on female sizes and body condition of nesting olive ridley turtles (Lepidochelys olivacea) in La Escobilla Beach Sanctuary, Mexico

Body condition (BC) can affect the reproductive output and hatchling survival of nesting olive ridley turtles (Lepidochelys olivacea). However, little is known about the BC of nesting females during the arrival event at nesting sites. Therefore, this study aimed to evaluate the BC of females nesting in La Escobilla Beach Sanctuary (La Escobilla) during the 2021 nesting season. Nesting females were measured and weighed. The mean size for nesting L. olivacea was 60.41 ± 2.98 cm for straight carapace length, 52.69 ± 2.57 cm for straight carapace width, and 34.35 ± 3.94 kg for weight (n = 483). The mean (± standard deviation, SD) Fulton's/Bjorndal BC index estimated for nesting females was 1.54 ± 0.15, while the mean (± SD) of body mass index was 2.18 ± 0.23. Based on these indexes, 28 individuals were classified as in bad condition, 315 in good condition, and 19 in excellent condition. This first estimation of the olive ridley turtle body condition in a nesting colony showed that BC is a good body condition for most nesting females in La Escobilla. This study is a valuable baseline for nesting L. olivacea's health condition.

How inquilinism shaped breeding systems in a termite host-inquiline relationship.

Social insects have developed a broad diversity of nesting and foraging strategies. One of these, inquilinism, occurs when one species (the inquiline) inhabits the nest built and occupied by another species (the host). Obligatory inquilines must overcome strong constraints upon colony foundation and development, due to limited availability of host colonies. To reveal how inquilinism shapes reproductive strategies in a termite host-inquiline dyad, we carried out a microsatellite marker study on Inquilinitermes inquilinus and its host Constrictotermes cavifrons. The proportion of simple, extended and mixed families was recorded in both species, as well as the presence of neotenics, parthenogenesis and multiple foundations. Most host colonies (95%) were simple families and all were monodomous. By contrast, the inquiline showed a higher proportion of extended (30%) and mixed (5%) families, and frequent neotenics (in 25% of the nests). This results from the simultaneous foundation in host nests of numerous incipient colonies, which, as they grow, may compete, fight, or merge. We also documented the use of parthenogenesis by female-female pairs. In conclusion, the classical monogamous colony pattern of the host species suggests uneventful development of simple foundations dispersed in the environment, in accordance with the wide distribution of their resources. By contrast, the multiple reproductive patterns displayed by the inquiline species reveal strong constraints on foundation sites: founders first concentrate into host nests, then must attempt to outcompete or absorb the neighbouring foundations to gain full control of the resources provided by the host nest.

Colony life history of the tropical arboreal ant, Cephalotes goniodontus De Andrade, 1999

Arboreal ants are ecologically important in tropical forests, but there are few studies using DNA markers to examine their population and colony structure. Colonies of the arboreal turtle ant Cephalotes goniodontus create trail networks through the canopy of the tropical forest, in dense vegetation where it is difficult to determine how long a nest is used and how neighboring colonies partition space. We monitored 53 nest sites for up to six years and, using seven microsatellite markers, genotyped samples of workers collected at or near 41 nests over 1–4 years. We calculated average relatedness within samples collected at a given location, and between samples collected at the same location in successive years, and performed pedigree analysis to predict the number of queens that produced each sample of workers. Fifteen samples were highly related (r ≥ 0.6) from single colonies, of which 11 were monogynous and the remaining four had two queens; 19 were of intermediate relatedness (0.1 ≤ r < 0.6) with 1–6 queens, and 7 were groups of unrelated workers (r < 0.1) from at least 4 queens. Colonies persisted at the same nest site for 2–6 years. The smallest distance we found separating nests of different colonies was 16.2 m. It appears that different colonies may share foraging trails. Our study demonstrates the feasibility of using a cost-efficient genotyping method to provide information on colony structure and life history of ant species.

Nesting habits of Baya Weaver Ploceus philippinus (Linnaeus, 1766) on power and television cables in the agricultural landscape of Kallakurichi district, Tamil Nadu, India

The nesting habits of Baya Weaver Ploceus philippinus with nesting site (e.g., power and television cables), source of nest materials, various developmental stages of nests, abnormal nests, number of individuals and their association with other bird species, and threats to their nests were studied between March and September 2021 in the agrarian landscapes of 42 villages in Kallakurichi District, Tamil Nadu. A total of 155 nest colonies containing 1,725 nests of various developmental stages and 1,993 adult birds were counted on power/television cables. The number of nests per colony found varied from one to 57. The average number of nests per colony was eleven. Baya Weaver had preferred power/television cables as nesting sites in the study area in spite of availability of potential nest-supporting trees, such as Cocos nucifera and Borassus flabellifer within 500 m radii from cables bearing nests. Birds used fibres of sugarcane leaves (Saccharum officinarum) for the construction of nests. Out of 778 helmet stage nests observed, 90% (n = 716) helmet stage nests had clay deposits on their inner walls and no clay deposits were found in the remaining 10% (n = 62) helmet stage nests. Eleven types of abnormal nests constituted 17% (n = 286) of the total nests. Sixteen other bird species (e.g., birds of order: Passeriformes, Coraciiformes, Piciformes, Cuculiformes and Columbiformes) were found associated with the individuals of Baya Weaver. These bird species strictly shared similar roosting and foraging grounds. The avian predators such as House Crow Corvus splendens, Large-billed Crow Corvus macrorhynchos, Black Drongo Dicrurus macrocercus, Rufous Treepie Dendrocitta vagabunda, Coucal Centropus senegalensis, and Shikra Accipiter badius had damaged the nests, eggs and chicks. The study revealed that about 1.1% nests (n = 197) were probably damaged by these avian predators. Power cables in the study sites had provided suitable nesting sites for Baya Weavers. The causes for utilization of power cables as nesting sites in larger geographical areas require further studies.

A Neoponera villosa (Fabricius, 1804) Worker Pupa with too Many Legs (Hymenoptera: Formicidae).

Several somatic and sexual anomalies such as gynandromorphism and other morphological malformations have been described in ants, but cases of supernumerary legs in natural populations are rare, with only six cases reported to date. Moreover, few cases of abnormalities have been reported for the Ponerinae subfamily, with only three cases of genetic chimeras and five teratological cases worldwide. We report here a new case of teratology in this subfamily, with a seven-legged worker pupa found in a Neoponera villosa colony nesting in an epiphytic tank bromeliad. This is the second case for Mexico of a morphological anomaly in a ponerine ant, but the first report of a teratological case in the subfamily for this country.

The termitaria terminator: Can Actinobolus beetles affect the relationships between termitaria and related fauna in the Brazilian Cerrado?

AbstractTermites are key components of tropical ecosystems, particularly in the Cerrado biome, where they dominate animal biomass and play crucial roles in nutrient cycling and soil formation. Their abundance and nutritional value make them primary food sources for various Cerrado animals, influencing predator diversity and several ecological interactions. Additionally, termite mounds serve as essential shelters for a wide range of fauna, aiding in thermoregulation and providing refuge from harsh environmental conditions, including wildfires. In this scenario, termitaria survival, diversity, and availability have several effects on the Cerrado fauna ecology. We present novel insights into the interaction between Actinobolus beetles and epigeous termite mounds in the Cerrado. Our field observations revealed Actinobolus beetles utilizing termite mounds for feeding and reproduction in several localities of Cerrado. These beetles access the inner portion of the termitaria, where the colony nest is located and protected by the termitaria's harder external layer and their larvae consume the termite nest structure. Actinobolus attack leads to partial or complete destruction of the colony and the creation of large hollows inside the mounds, causing deep changes in its structure. Despite the defensive mechanisms of termites, Actinobolus larvae thrive within the nest and likely ingest termites’ eggs, nymphae and adults. Furthermore, we found that the Actinobolus capsule are made of faecal pellets, instead of termitaria debris. We suggest that the interaction between Actinobolus beetles and epigeous termitaria impacts the role of termitaria in providing microclimate regulation, food and shelter for Cerrado fauna, likely having poorly understood effects on the conservation and management of Cerrado ecosystems.

Population size and nesting peculiarities of the black-headed gull Chroicocephalus ridibundus (Linnaeus, 1766) on the territory of water treatment facilities

Background. Today, the black-headed gull inhabits man-made areas of wastewater treatment facilities (WTF) to comensate for the the reduction of natural aquatic and wetland habitats. Over the last decade, a nearly tenfold increase in its population has been recorded, despite a low reproduction rate. This fact indicates the lack of stability in the bird population, necessitating thorough research. Materials and Methods. The analysis of the population size and biological charac­teristics of black-headed gulls involved censuses and observations at the WTF of the city of Kharkiv using conventional methods during the spring-summer periods of 2020–2021 and 2023. Results. The population of the black-headed gull reached its peak in the third decade of May 2020 (2637 individuals) and 2023 (2124 individuals), as well as in the second decade of May 2021 (3949 individuals). The maximum nesting density was observed on sludge sites (SS) of wastewater treatment facilities that are most similar to natural habitats, where dried mud alternates with water patches and vegetation at the bottom and around the perimeter (Type V): 236.7±26.7 pairs/ha in 2020 and 242.9±28.5 pairs/ha in 2021. The majority of nests were found in the first decade of May 2021 and the third decade of May 2020. The black-headed gull forms mixed-species, occasionally monospecific subcolonies. Nesting in association with it were: Sterna hirundo, Anas platyrhynchos, Spatula clypeata, Vanellus vanellus, Charadrius dubius, Himantopus himantopus, Fulica atra, Gallinula chloropus, and Aythya ferina. The size of the complete black-headed gull clutch was 3.1±0.4 eggs (n = 190). The egg dimensions were 50.9±2.1 ´ 36.2±1.1, with a mass of 34.6±2.8 g. Regarding shell coloration, five types of background colors were identified. Mass egg laying occurred from the third decade of April to the first decade of May, constituting 40.3 % (n = 993) in 2020 and 62.3 % (n = 1757) in 2021. The egg-laying period extended from April to July, with the latest non-incubated clutches recorded in the first decade of July (3.07.2020). The first chicks were found in nests in the first decade of May, while mass hatching occurred in the second half of May. The latest registration dates of the birds on nesting territories were in the second decade of July for 2020 and 2023, and the first decade of August for 2022. The nesting season duration varied from 125 to 140 days in different years. Autumn migration commenced with summer relocations and concluded from late October to early November. The reproductive success – the percentage of nestlings that fledged and successfully achieved flight – constituted 29.2 % (n = 2404 of laid eggs) in 2020, and 15.5 % (n = 6138) in 2021. The majority of offspring perished due to changes in water levels (prolonged rainfall or industrial wastewater discharge), predation, disturbance factors, etc. Conclusion. The colonial nesting of the black-headed gull creates favorable conditions for the habitation and reproduction of various bird species, including rare ones, which is essential for their conservation.

Exploring the influence of ground-dwelling ant bioturbation activity on physico-chemical, biological properties and heavy metal pollution in coal mine spoil

Coal mining activities increase the soil concentrations of heavy metals manifold thus impacting soil health and biodiversity. The understanding of the impact of bioturbation activities by ant colonies on soil in coal mine spoil site across different restoration ages is not studied. The study aimed to investigate the influence of bioturbation activities by two most common and distinct coal mine site inhabiting ant species (C. compressus and C. longipedem) at six different ages (2, 4, 6, 8, 10 and 12 years old) on the soil heavy metal concentrations of Fe, Zn, Mn, Cu, Ni, Pb, Cd and Cr, pH, OM, TC, TN, soil enzyme activity of DH, ACP, β-glucosidase and proteases properties of soil. Soil samples were collected from opencast coalmine spoils during October and November 2017. Reference (Ref.) soil samples (n=10 per site) were collected (from area adjacent to ant nest colony approximately 2–5 m distance) from a depth of 0–15 cm and ant nest debris soil of each ant species (n=10 per site) were collected from each site. Heavy metal pollution decreased and pH, OM, TC, TN and soil enzyme activity of DH, ACP, β-glucosidase and proteases of soil in both Ref. soil and ant nest debris soil increases with the increase of mine site restoration age. Our study revealed that different age of the mine spoil have more profound effects on the soil quality and heavy metal content. Contrary to our hypothesis, regression analysis did not support our notion that ant bioturbation activity directly accelerate heavy metal breakdown. Instead, our findings suggests that ant colonies prefer to construct their nest for the locations with lower heavy metal concentrations and higher enzyme activity and increase in soil porosity is a key factor behind the low heavy metal concentration in the nest debris soil.

Social foraging and the associated benefits of group-living in Cliff Swallows decrease over 40 years.

Animals that feed socially can sometimes better locate prey, often by transferring information about food that is patchy, dense, and temporally and spatially unpredictable. Information transfer is a potential benefit of living in breeding colonies where unsuccessful foragers can more readily locate successful ones and thereby improve feeding efficiency. Most studies on social foraging have been short-term, and how long-term environmental change affects both foraging strategies and the associated benefits of coloniality is generally unknown. In the colonial Cliff Swallow (Petrochelidon pyrrhonota), we examined how social foraging, information transfer, and feeding ecology changed over a 40-year period in western Nebraska. Relative to the 1980's, Cliff Swallows in 2016-2022 were more likely to forage solitarily or in smaller groups, spent less time foraging, were more successful as solitaries, fed in more variable locations, and engaged less in information transfer at the colony site. The total mass of insects brought back to nestlings per parental visit declined over the study. The diversity of insect families captured increased over time, and some insect taxa dropped out of the diet, although the three most common insect families remained the same among the decades. Nestling Cliff Swallow body mass at 10 days of age and the number of nestlings surviving per nest declined more sharply with colony size in 2015-2022 than in 1984-1991 at sites where the confounding effects of ectoparasites were removed. Adult body mass during provisioning of nestlings was lower in more recent years, but the change did not vary with colony size. The reason(s) for the reduction in social foraging and information transfer over time are unclear, but the consequence is that colonial nesting may no longer offer the same fitness advantages for Cliff Swallows as in the 1980's. The results illustrate flexibility of foraging behavior and dynamic shifts in the potential selective pressures for group-living.

Monitoring observations of the southernmost breeding population of Long-billed Vultures Gyps indicus (Scopoli, 1786) (Aves: Acciptriformes: Accipitridae) in the Nilgiri Biosphere Reserve, India

The Long-billed Vulture (LBV) population was systematically monitored across four nesting colonies in the Nilgiri Biosphere Reserve (NBR) throughout three extended breeding seasons. Breeding success rates between years ranged from 83.33% in 2018–2019 and 62.5% in 2020–2021. Nesting was monitored at the cliff sites, consistent with prior research. Overall population fluctuations were minimal, varying between 21 individuals in 2020–2021, 17 individuals in 2018–2019, and 16 individuals in 2019–2020. There was an apparent impact of forest fires and other human disturbance activities, and certain proactive conservation measures are proposed to help address these. There was indirect evidence of other threats including poison baits targeting wild carnivores and non-steroidal anti-inflammatory drugs (NSAIDs) being widely available for use in domestic livestock. The study endorses the approach of establishing vulture-safe zones, which focus on addressing the local threats. This includes raising awareness about wildfire management, controlling toxic NSAIDs availability that are harmful to vultures, discouraging the illegal use of poison-baits, and highlighting the necessity of monitoring threats posed by power infrastructure. Due to the high mobility of LBVs, all these threats need addressing through large-scale vulture safe zone work (up to 100 km radius) surrounding the breeding colonies to secure the LBV’s long-term survival. These conservation actions are urgently needed.

Trypanosomiasis: An emerging disease in Alpine swift (Tachymarptis melba) nestlings in Switzerland?

Alpine swifts (Tachymarptis melba) are sub-Saharan migratory birds, which, in Switzerland, nest in colonies that have been continuously monitored for over 40 years. In the summer of 2022, despite favourable environmental conditions, an unexpectedly high number of sudden mortalities (30–80%) occurred in 20 to 45-day-old nestlings from several nesting sites, of which 3 were monitored in detail. Nestlings submitted for post-mortem analysis (n = 5) were in good body condition but exhibited extensive subcutaneous haematomas (n = 5), myocardial petechiae (n = 2) and stunted growth of primary feathers (n = 1). In all birds, 4–5 μm large, amastigote-like protozoans were identified in skeletal and cardiac muscle sections. These tissues tested positive in a PCR targeting the 18S-rRNA gene of Trypanosoma spp. Amplified sequences showed 99.63% identity with sequences of Trypanosoma corvi (JN006854 and AY461665) and Trypanosoma sp. (AJ620557, JN006841). 72 blood smears of 45-day-old nestlings from two colonies were assessed, of which 20 contained trypomastigote forms, some with high parasitaemia (highest average of 56.4 in 10 high power fields, 400x magnification). Trypomastigote morphometrics (n = 36; mean total length = 30.0 μm; length of free flagellum = 5.8 μm) were consistent with those of T. bouffardi. These findings suggest that an avian trypanosomiasis causing mass nestling mortality could be an emerging disease in Swiss Alpine swift populations.

Morphometrics of Heterotrigona Itama Nest Components in the Pocut Meurah Intan Grand Forest Park, Aceh Besar Regency, Indonesia

This study aims to describe the morphometrics of the nest components of the stingless bee species of the Heterotrigona itama species in the Pocut Meurah Intan Grand Forest Park, Aceh Besar Regency, Indonesia. This research method uses direct observation of five H.itama nest colonies which includes measurements of each nest component, namely baby cells, pollen pots, honey pots and nest entrances. The results of this study reported that the nest components of five H.itama colonies had varying sizes. The entrance to the H. itama nest is tube-shaped with a tube length of 2.50 - 18.00 cm and a diameter of 1.50 - 4.50 cm. The diameters of pollen pots, honey pots and daughter cells are in the range of 0.95 - 1.14 cm, 0.65 - 1.14 cm and 0.30 - 0.34 cm respectively. The height of the pollen pot, honey pot and daughter cells ranges from 1.24 - 1.64 cm, 0.63 - 1.20 cm and 0.44 - 0.50 cm respectively. From the results of this research, it can be concluded that H.itama found in the Pocut Meurah Intan Grand Forest Park, Aceh Besar Regency, Indonesia has varying morphometrics in each colony.

Soldier phenotypic differences among 2 invasive and destructive Coptotermes species and their hybrids (Blattodea: Isoptera: Rhinotermitidae).

With recent evidence of hybridization events in the field, the phenotypic traits of F1 hybrid colonies of 2 destructive subterranean termite species, Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) remain to be investigated. In this study, laboratory colonies of 2 conspecific pairings and 2 heterospecific pairings (hybrid F = ♀C. formosanus × ♂C. gestroi, hybrid G = ♀C. gestroi × ♂C. formosanus) were examined in Florida, USA, and in Taiwan. Colony nest architecture for both hybrids displayed disorganized carton materials compared to the defined trabecular carton of both parental species. Soldier head measurements were not a reliable approach for diagnostic purposes, as soldier morphometric traits widely overlapped across all mating combinations, except for hybrid F soldiers displaying abnormally long mandibles. Hybrid F soldiers' mandibles also remained parallel when at rest. However, 4 qualitative morphological differences in soldiers were determined for diagnostic purposes. First, the fontanelle in both hybrids is horizontally ellipsoid whereas subcircular in C. gestroi and trianguliform in C. formosanus. Second, sclerotized striations along the postmental sulcus are present in C. gestroi, absent in C. formosanus, and intermediate in both hybrid soldier types. Third, each lateral margin of the fontanelle is flanked by 2 setae in C. formosanus and both hybrids, while a single seta resides on each side of the fontanelle in C. gestroi. Finally, C. gestroi and hybrid soldiers' heads are characterized by a bulging vertex that is lacking in C. formosanus. Therefore, a combination of these 4 characteristics now allows for soldier identification of hybrid Coptotermes.

Nest construction and repairing habits of Baya Weaver Ploceus philippinus (Aves: Passeriformes: Ploceidae) in the agricultural landscape of Villupuram District, Tamil Nadu, India

The intricate nesting habits of Baya Weaver Ploceus philippinus were studied on two Palmyrah Palm Borassus flabellifer trees in Chendur village, Villupuram district, Tamil Nadu between 20 March and 30 November 2020. Observations concentrated on sources of fibers, developmental stages of nests, re-construction &amp; repairing of nests, deposition of clay in the nest walls, and various threats. A total of 98 nests of various developmental stages (wad stage—4, helmet stage—31, egg-chamber closed stage—5, and complete nests—58) were studied on these two nest colonies. The birds used leaf fibers of Indian date Palm Phoenix sylvestris and Sugarcane Saccharum officinarum as nest materials, and took 6–48 days for construction of a complete nest. 95% of helmet stage nests (n = 126) contained clay deposits. Analysis of plastered clay revealed it was alkaline with pH 9, and dry weight ranged from 5.1–5.8 g. Males re-constructed new nests from the remnant stalks attached to tips of palm fronds, and also made repairs on damaged nests. Anthropogenic factors, wind, rain, and avian predators, such as House Crow Corvus splendens, Long-billed Crow Corvus macrorhynchos, Rufous Treepie Dendocitta vagabunda, and Shikra Accipeter badius posed threats to Baya Weavers. A total of 42 nests, 11 broken eggs, and 14 dead chicks were found fallen under the two supporting trees. The detailed systematic survey covering entire district, rapid urbanization, and the anthropogenic pressures will help in nest drafting an action plan to conserve local populations of Baya Weaver.

Sebaran dan Karakter Morfologi Lebah Madu Hutan Apis dorsata (F.) di Pulau Sermata Kabupaten Maluku Barat Daya

This study aims to determine the distribution and morphological characteristics of the forest bee (Apis dorsata F.) on Sermata Island, Southwest Maluku Regency. The research was conducted in Pupliora Village, Mahaleta Village, Rumkisar Village and Batu Gajah Village on Sermata Island from November to December 2021. The method used in this study was a survey methode on each nest of A. dorsata [F.] forest honeybees on Sermata Island. The results showed that the distribution of Apis dorsata F. forest honey bee hives found on Sermata Island was 51 active nest colonies and 37 inactive nests, at an altitude of 38-215 m asl, with nesting sites found, namely mango trees, breadfruit trees, banyan trees, salawaku trees and rock cliffs. For heights from the ground surface ranging from 4-29 m. The average size of the morphometric characters of Apis dorsata worker bees found was body length 2.0-2.2 cm, head width 0.4-0.5 cm, body length 2.0-2.2 cm, head width 0.4-0.5 cm, head 0.4-0.6 cm. Front wing length 1.3-1.4. The size of the hind wings is 0.9 cm, and the length of the hind legs is 1.1-1.2 cm.

Seasonal variation in defense behavior in European and scutellata-hybrid honey bees (Apis mellifera) in Southern California

Nest defense in the honey bee (Apis mellifera) is a complex collective behavior modulated by various interacting social, environmental, and genetic factors. Scutellata-hybrid (“Africanized”) honey bees are usually considered to be far more defensive than European honey bees which are therefore preferred for commercial and hobbyist beekeeping. In the most recent zone of scutellata hybridization, the southern USA, the degree to which this defensiveness differs among current strains, and the extent to which defensiveness varies across a season has not been measured. We quantified the levels of A. m. scutellata ancestry in colonies and conducted a seasonal assessment (May through November) of colony nest defensiveness in feral scutellata-hybrid and a popular lineage of European honey bee commonly used in managed environments (sold as A. mellifera ligustica) hives at two apiaries in Southern California. Standard measures of defensiveness were low in both scutellata-hybrid and European colonies during May. Defensiveness increased during the later months of the study in scutellata-hybrid colonies. Most measures of defensiveness did not increase in managed colonies. Defensiveness in the scutellata-hybrids appears lower than what has been previously documented in Brazil and Mexico, possibly due to their lower proportion of A. m. scutellata ancestry.

Reproductive benefits and reduced investment in parental care behavior associated with reproductive groups of males in Abudefduf troschelii.

Fishes of the family Pomacentridae present a wide diversity of mating systems, ranging from polygyny to promiscuity and from individual territorial defense to the establishment of reproductive colonies of males. The damselfish species Abudefduf troschelii has a reproductive colony mating system, in which males temporarily aggregate in reproductive areas to court and attract females. Males defend an individual territory where they receive eggs and perform paternal care behaviors for their offspring. The present study evaluated the advantages of the colonial mating system in A. troschelii. During an entire reproductive period, in a breeding colony within a rocky reef, we located, marked, geo-referenced, and measured the distances between the territories of all males. We quantified the variance among males in their patterns of paternal care investment, eggs acquired, hatching success, reproductive success, body size, and changes in body coloration. We found that males spatially distributed their nests in groups or independently (i.e., solitary nests). Nesting groups are formed by larger males that show intense nuptial coloration during the entire receptivity period. They are located centrally to the colony and consist of three to six males whose territories overlap. In contrast, small solitary males that fail to acquire or maintain nuptial coloration during the receptivity period establish their nests peripherally to the colony, away from the territories of other males. Our results highlight that the reproductive benefits of colonial nesting are unequal for males, as the spatial distribution of nests within the colony determines the reproductive success of males. Group nesting confers the highest reproductive benefits to males regarding eggs obtained, hatching success, and relative fitness and also enables males to reduce their parental investment in brood care behaviors. The preference of females for oviposition could be associated with greater intrasexual competitiveness, defense ability, body condition, or experience of group-nesting males located at the center of the colony or because their progeny will have a lower probability of predation than they would in solitary nests males.

Nest success of ground-nesting ducks in the wetlands of Great Salt Lake, Utah.

The number of ground-nesting ducks in the wetlands of Great Salt Lake, Utah has drastically decreased in the past few decades. A potential cause for this decline is the increase of predator species and their abundances, which has caused most nests to fail from depredation. Ground-nesting ducks may be able to reduce the risk of nest depredation by selecting nest sites where local physical structures or vegetation provides olfactory or visual concealment. To test this, we used logistic exposure models to look at the effect of nest-site characteristics on daily survival rates (DSRs) of nests during 2019, 2020, and 2021 in the wetlands of Great Salt Lake, Utah. We found 825 duck nests including 458 cinnamon teal (Spatula cyanoptera), 166 mallards (Anas platyrhynchos), and 201 gadwalls (Mareca strepera). DSRs were 0.9714 ± 0.0019 in 2019, 0.9282 ± 0.0049 in 2020, and 0.8274 ± 0.0185 in 2021. Survival rates varied among years but not among duck species. Striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) were responsible for 85% of depredated nests. Nests located near other duck nests had higher DSRs than more dispersed nests. Neither visual nor olfactory characteristics correlated with increased DSRs based on AICc analysis. Nests located inside a mixed nesting colony of American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and common terns (Sterna hirundo) had higher DSRs than duck nests outside the colony. Increased nesting densities of ducks and other colonial waterbirds had the greatest impact on nesting success. Increased nest density may be encouraged through early spring green-up.

The usefulness of unmanned aerial vehicles (UAV) in white stork censusing

Unmanned aerial vehicles (UAV) are effective and often noninvasive tools successfully used in bird monitoring. However, when handling long-term data in the context of population changes, the consistency of methods over time is essential as the method-related bias may lead to wrong conclusions. In two distinct populations of white stork Ciconia ciconia, in Poland and Spain, we compared two censusing methods: traditional observation by a human from the ground and using UAV. We recorded the number of recorded fledglings, the time needed to obtain this information, and the number of detected breeding pairs in colonies. We investigated 57 and 117 nests in Poland and Spain, respectively. In Poland and Spain, the number of fledglings was significantly lower when recorded by human observer than by UAV, i.e., 2.21 vs. 2.60 and 1.35 vs. 1.55. The probability of mistakenly recording the number of fledglings by the observer was significantly lower in colonial white storks in Spain than in solitary nesting in Poland. The mean time needed to record the number of fledglings was significantly longer when using a UAV than by a human observer in both populations. The mean number of detected nests in colonies in Spain differed significantly between the human observer and UAV, 13.1 vs. 7.4, respectively. The difference between human and UAV in recorded pairs was higher when colonies were on trees than on human-made structures. We conclude that introducing UAVs in long-term studies may affect the results and should be performed cautiously.

Habitats and nesting habits of Streaked Weaver Ploceus manyar in select wetlands in the northern districts of Tamil Nadu, India

The habitats and nesting habits of Streaked Weaver Ploceus manyar was studied in the Narrow Leaf Cattail Typha angustifolia (Typhaceae) wetlands in Ranipet, Kancheepuram, and Viluppuram districts of northern Tamil Nadu. A total of 349 nests, in various developmental stages, in 24 colonies and of 536 adult individuals were enumerated. Of these 349 nests, 43 nests were in wad stage, 28 in ring stage, 123 in helmet stage, 55 egg-chamber-closed stage, and 100 complete nests including two abnormal nests were recorded. Streaked Weaver used fibres of T. angustifolia for building nests. Females were also observed to be engaged in nest construction, while males placed blobs of cow dung on the inner or both walls of helmet stage nests before pairing with females; 88.7% helmet stage nests had deposition of cow dung on their inner walls and the remaining 11.3% nests had no such deposits. In 59% nests the entrance tubes were found facing east. They showed communal foraging and the flock size ranged from 50─80 birds. No antagonistic interactions were observed between Streaked Weavers and other species over sharing of common perching sites and foraging grounds. Harvesting of nest-supporting reeds and sightings of avian predators, such as House Crow Corvus splendens, Large-billed Crow Corvus macrorhynchos, and Rufous Treepie Dendocitta vagabunda near nest colonies may pose threats to Streaked Weavers.