Predation on eggs of Schneider’s dwarf caiman,Paleosuchus trigonatus (Schneider, 1807), by armadillos and other predators

Nests of Schneider’s dwarf caiman, Paleosuchus trigonatus, were located in the forests around three streams that drain into the Xingu River, Brazilian Amazonia, in October 2014. Camera traps were installed at the edge of four nests to document predators and female parental care. At two nests, females unsuccessfully defended their nests against one or more giant armadillos, Priodontes maximus, and nine-banded armadillos, Dasypus novemcinctus. Both armadillo species responded to the attack by fleeing and returning on the opposite side of the nest by going around the tree under which the nest was located. Giant armadillos have never before been recorded consuming caiman eggs and their diet has been described as consisting mostly of ants and termites. Another species of armadillo, Cabassous unicinctus, was also registered digging into a nest and probably consuming eggs, though it is generally considered to be primarily insectivorous. A tayra (Eira barbara), lizard (Tupinambis teguixin) and coati (Nasua nasua) were also registered taking eggs from nests during the day, but we obtained no registers of nest defence by caimans during the day. The three nests were attacked after 60 days of incubation, when the eggs were well developed.     

Breeding biology of the Sayaca Tanager (Thraupis sayaca) in southeast Brazil

ABSTRACT

Thraupis is a genus of the American endemic Thraupidae (subfamily Thraupinae), comprising seven species that inhabit tropical forests to urban centres. The Sayaca Tanager (Thraupis sayaca) is a disturbance-tolerant species of high representativeness in plant-frugivore networks, but information on its breeding biology is scarce and often restricted to non-systematic surveys. We studied the breeding biology of the T. sayaca, following 39 active nests in a periurban area of southeast Brazil during two breeding seasons (2017/2018, 2018/2019). The breeding season ranged from early September to middle December, and the nests were placed in native and exotic plants and human buildings (nest height above ground: 3.35 ± 1.73 m, mean ± SD). Only females incubated and brooded, but both adults built the nests, fed the nestlings, and removed their faecal sacs. Clutch size was 2.86 ± 0.38 eggs and nest attentiveness was 71.2%. The incubation and nestling periods were, respectively, 13.4 and 17.4 days. Males and females did not differ on nestling provisioning and nest sanitation rates. Nestling provisioning (13.35 ± 6.25 trips/hour) increased with nestling age, while mean brooding time was 37.2% and decreased with nestling age. Apparent nest success was 38.7%, and nest survival according to the Mayfield method was 27.2%. Five nests (20.8%) were parasitised by the Shiny cowbird (Molothrus bonariensis), and we recorded five events of nest-site reuse. We concluded that the most remarkable breeding traits of T. sayaca in comparison with close-related tanagers are the use of anthropogenic nest sites, the higher clutch size and number of feeding trips, and the longer nestling period.     

Reproductive biology of the endangered wattled curassow (Crax globulosa; Galliformes: Cracidae) in the Juruá River Basin,Western Brazilian Amazonia

The reproductive biology of Crax globulosa is virtually unknown, this knowledge comprised of only a few anecdotal notes. We found nine nests of Crax globulosa in the middle section of the Juruá River, western Brazilian Amazon, during the dry season. Nests averaged 22.5 m from water and 13.3 m above the ground. We observed two nest types: five made of twigs, leaves and vines, and four within a bromeliad. All nests contained two eggs, but six (67%) were subsequently predated. A female tagged with a transmitter nested twice during the same breeding season. A chick was monitored together with its parents for > 10 months. In addition to hunting and habitat loss, nest predation could be another threat to this endangered species.     

Camera traps capture images of predators of Caiman crocodilus yacare eggs (Reptilia: Crocodylia) in Brazil’s Pantanal wetlands

Camera traps were set up in forest nests in 2009, 2010 and 2012 to capture images of possible predators eating eggs of the Pantanal caiman, Caiman crocodilus yacare. We monitored 57 caiman nests; 42 nests were opened and the eggs were counted (mean = 25 eggs/nest, SD = 4.3). Females were present and captured at 38 of those nests. The remaining 15 nests were used as controls, and we did not capture the females or open the egg cavities of these nests. Most of the nests had the eggs eaten by predators, in both the disturbed group (38 nests) and the control group (13 nests). The main predators were carnivorous mammals, such as crab-eating foxes (Cerdocyon thous), coatis (Nasua nasua) and tayras (Eira barbara), although feral pigs (Sus scrofa) and armadillos (Dasypus novemcinctus) were also photographed eating caiman eggs. The lizard Salvator merianae was photographed eating eggs of two nests.     

On the natural history of the South American pepper frog,Leptodactylus labyrinthicus (Spix, 1824) (Anura: Leptodactylidae)

Some species of Leptodactylus of the L. pentadactylus group lay their eggs outside water but the tadpoles need to reach water to complete the larval phase; other species complete development in terrestrial nests. Here we present details of the reproduction of L. labyrinthicus in south‐eastern Brazil. The proportion of tadpoles and trophic eggs in aged egg clutches was determined, as well as the growth of the tadpoles while in the nest. The gut contents of tadpoles that were in egg clutches of frogs were analysed. Adult males did not differ from females in size and had hypertrophied forearms and an enlarged spine on the thumb. Reproduction was initiated with the first rains of August/September and extended to mid‐January. Calling and spawning occurred at permanent or temporary water bodies. The foam nests were built in excavated basins outside of, but close to the water. The male determined the place of the basin construction; after amplexus, the female completed the excavation. The amplexus was axillary. One female spent the day after spawning in the foam. The eggs were pale grey, the yolk averaging 2.3?mm in diameter. The mean number of eggs was 2101 per egg clutch. The number of tadpoles in individual nests varied between 0.05% and 11.40% in relation to the total laid eggs. The tadpoles entered water when rains flooded the basin. The tadpoles grew to 12 times the weight of an individual egg while in the nest; no nesting tadpole was beyond stage 25. The longest time we followed tadpoles in a nest was 25 days. Tadpoles were found preying upon eggs of three other frog species and upon conspecific eggs. Males fought by grasping each other in a belly‐to‐belly position; the powerful arms and the thumb spines represent weapons. Even though males can reach maturity in the season following birth, small size would prevent them from establishing their own territory. All the species of the L. pentadactylus group may build their foam nests within excavated basins. The basins may protect the eggs and embryos from cannibalistic tadpoles and may have an anti‐desiccation effect. In order to produce trophic eggs, the female may delay laying additional unfertilized eggs until after the male has abandoned the foam nest. Anuran eggs represent an important food item for tadpoles after they leave the nest.     

Breeding biology of the threatened Campo Miner Geositta poeciloptera (Aves: Scleruridae), a Neotropical grassland specialist

The Campo Miner is a threatened grassland passerine endemic to the South American Cerrado, whose life history is almost unknown. In this paper, we studied during three breeding seasons (2014 to 2016) the breeding biology of a colour banded population of the species found in the Upper Rio Grande Grasslands, south-eastern Brazil. We found 98 nests, 81 of which became active and were monitored. The Campo Miner breeds in frequently burnt-and-grazed natural grasslands, successfully nesting in highly disturbed sites, such as dirt banks along roads and even in mine pits. The species is socially monogamous and both parents build the nest, which is a cavity/with-tunnel/simple/platform type. The nest chamber is lined with a platform made of grass fragments, charcoal, hairs, and mammal faeces. The most common clutch size is three eggs (n = 66), with some nests containing one (n = 1), two (n = 12) or four eggs (n = 2). The egg is white and pyriform and the incubation, performed by both parents, lasts 17.5 days. Mean nestling period is 15.5 days, with both parents feeding the young. Breeding season lasted for about 125 days (August to December) and multiple breeding attempts in a single season were common, with a maximum of three attempts recorded. All species of Scleruridae built their nests inside cavities dug in the soil with an access tunnel to it, where they lay a small clutch (usually 2–3 white eggs), but no other species in the family has been studied in detail to date. Further studies are required to understand why a species apparently tolerant to anthropogenic impacts such as G. poeciloptera can be so rare, patchily distributed and threatened throughout its range.     

Structural comparisons of isomorphic breeding nests between closely allied spiders Cheiracanthium japonicum and Cheiracanthium lascivum (Araneae: Eutichuridae)

Closely allied spider species Cheiracanthium japonicum and Cheiracanthium lascivum make a closed breeding nest for egg laying and parental care. The nest provides the internal climatic stability required for suitable development of eggs and the physical durability required for protection against intruders. Although the breeding nests of these two spiders are quite similar in structure and appearance, their climatic stability and physical durability seem to be empirically different. Such physical features of the nests of these two spiders were compared based on a balance between the inner and outer air temperature and humidity of the nest as well as on the amount and size of spider silks lining the nest. In addition, the female’s relative energy allocation to egg production versus nest construction was examined based on the number or weight of eggs versus the climatic stability and physical durability of the nest. According to the results, the stability of temperature and humidity was maintained better in the breeding nest of C. japonicum than in that of C. lascivum. Furthermore, the nest of C. japonicum was more strongly constructed, with a greater volume and size of silks, than that of C. lascivum. On the other hand, the number or weight of eggs in relation to the female’s body weight in C. japonicum was smaller than that in C. lascivum. These results suggested that the reproductive effort towards nest construction for the purpose of egg and juvenile care in C. japonicum was larger than that in C. lascivum. In contrast, the effort towards egg production in C. japonicum was smaller than that in C. lascivum. Consequently, it is likely that the structural differences in breeding nests between these two spiders are responsible for the discrepancies in the female’s relative energy allocation to nest construction.     

Polygyny,oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants,Acromyrmex subterraneus (Hymenoptera: Formicidae)

ABSTRACT

Research related to the comparative biology of phylogenetically close ant species has received little attention, although it is the basis for understanding the systematics of some sibling groups. The objective was to study the polygyny, oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants. For that, we studied: oviposition rate – queens from three colonies were individually placed in plastic containers, and at 24-hour intervals, the laid eggs were quantified over a period of 96 hours; the workers’ life cycle – the development of immature ants was observed every 24 hours and, as a result, the duration of each stage of development was determined; the workers’ longevity – newly emerged adults were tagged and returned to the fungus chamber of their respective nests, and daily observations were made in each of the nest’s chamber. Laying rates were variable in the three queens studied, with a mean of total eggs laid of 271 for Acromyrmex subterraneus brunneus, 113 for Acromyrmex subterraneus subterraneus and 119 for Acromyrmex subterraneus molestans.The incubation period was 21.2 days in A. s. brunneus, 22.8 days in A. s. subterraneus and 20.4 days in A. s. molestans. The larval phase and pupal phase lasted on average 22.5 and 21.2 days in A. s. brunneus, 22.8 and 15.8 days in A. s. subterraneus and 17.2 and 14.2 days in A. s. molestans, respectively. Life cycle was different in the studied taxa, from 62 to 77 days in A. s. brunneus, from 59–68 days in A. s. subterraneus and from 51 to 55 days in A. s. molestans. The workers’ longevity varied between subspecies A. s. brunneus, A. s. subterraneus and A. s. molestans.     

Biology and defensive secretion of myrmecophilous Thiasophila spp. (Coleoptera: Staphylinidae: Aleocharinae) associated with the Formica rufa species group

Various aspects of the biology of the myrmecophilous Thiasophila angulata and T. szujeckii (Staphylinidae; Aleocharinae), mainly associated with the Formica rufa species group, are studied. The composition of defensive gland secretions from adults of T. angulata has been analysed. The complete development (egg-L_1-3-pupa-adult form), including adult overwintering, of both species takes place solely in ant nests. Under laboratory conditions, this lasts for about 22 days in T. angulata, and the period elapsing between the old and new generations of insects is approximately two months. The mean fecundity of adults of this species (28 eggs) was determined, as well as the duration of its reproductive period (mean 28.5 days), and lifespan (mean 67 days). In natural conditions T. angulata, found within nests of Formica polyctena and F. rufa, produces three generations, and the sibling species T. szujeckii one generation per year. These two species differ in their phenologies and abundance dynamics of adults and larvae, which is linked to the size and temperature regime of the host nest. The results of this study uphold the recent separation of T. angulata and T. szujeckii based on morphological features of adults and selected molecular markers. Adults and larvae of T. angulata forage on both live and dead food items accumulated by the host, as well as on the host’s eggs and larvae. Both the beetle larvae and adults remain unmolested among the host workers. The adults use their defensive gland secretions, which contains substantial quantities of toxic quinones, when necessary. According to the current categories of myrmecophiles, T. angulata (and by analogy, T. szujeckii as well) should be classified as a species wholly integrated with the host.     

Goliath frogs build nests for spawning – the reason for their gigantism?

ABSTRACT

In contrast to its popularity, astonishingly few facts have become known about the biology of the Goliath Frog, Conraua goliath. We herein report the so far unknown construction of nests as spawning sites by this species. On the Mpoula River, Littoral District, West Cameroon we identified 19 nests along a 400 m section. Nests could be classified into three types. Type 1 constitutes rock pools that were cleared by the frogs from detritus and leaf-litter; type 2 constitutes existing washouts at the riverbanks that were cleared from leaf-litter and/or expanded, and type 3 were depressions dug by the frogs into gravel riverbanks. The cleaning and digging activities of the frogs included removal of small to larger items, ranging from sand and leaves to larger stones. In all nest types eggs and tadpoles of C. goliath were detected. All nest types were used for egg deposition several times, and could comprise up to three distinct cohorts of tadpoles. Nests seemed to be clustered. Camera trapping revealed that nests are guarded by adult frogs at night. The breeding nests may allow the frogs to deposit their eggs away from the torrent rivers, and potential egg and tadpole predators. As nest construction, at least in some cases, requires the removal of large and heavy items, we hypothesize that this can only be achieved by decent sized frogs, possibly explaining the unique size of the species.     

Natural history of the Lined Seedeater Sporophila lineola (Aves: Thraupidae) in southeastern Brazil

The Lined Seedeater (Sporophila lineola) is a migratory species that inhabits a variety of open habitats in South America. We studied the breeding biology and territorial behaviour of a colour-banded population of the species in the Universidade Federal de Viçosa, Campus Florestal (1–19,8808ºS, –44,4136ºW), during two breeding seasons (2014/2015 and 2015/2016), which spans from December to April. We monitored 74 nests of this species. The nest is a low cup supported between a fork. Nests are mainly built with grass stems and rootlets, with spider-web used to hold the material together and to bind the nest to its supporting plant. Females are solely responsible for nest building and incubation, which is synchronic, and also for feeding nestlings to a large extent. Males are responsible for defending the territory, which corresponds to a small portion of the home range restricted to the nest environs, and also feed the nestlings. Mean clutch size is two eggs (78% of nests monitored), with clutches of three (20.3%) and four (1.7%) eggs also observed. Eggs are whitish, covered with dark brown blotches and spots to a variable extent. Mean incubation period, considered as the period between the onset of incubation and hatching of the first egg, is 11 days. Nestling period, considered as the period between hatching of the first egg and fledging of the last young, is 10 days. During the first breeding season, the simple percentage of successful nests was 34.1%, while the Mayfield success was 29.8%, with slightly higher values observed during the second breeding season, with 39.4% and 35.7%, respectively. We recorded, for the first time, three cases of polygamy in the species. We also recorded breeding site fidelity for the first time in the species, with males returning to the same territory owned in a previous breeding season.     

Aspects of the natural history of Leptodactylus knudseni Heyer, 1972 (Anura: Leptodactylidae) in a pristine forest in Central Amazonia,Brazil, with comments on ontogenetic variation of its tadpoles

The Leptodactylus pentadactylus species group is comprised of medium to large species of Neotropical frogs. Leptodactylus knudseni, a member of this species group, has a wide distribution throughout the Amazon Basin. Herein we describe aspects of the reproductive biology of L. knudseni and provide notes about the ontogenetic variation of its tadpoles based on a population in a non-flooded forest near Manaus, Amazonian Brazil. Amplectant pairs of L. knudseni lay foam nests in excavated basins on the edge of temporary ponds located on clay soil and at least 50 m from a stream. The tadpole development happens initially in the foam nests with access to the pond after the rain flooding the basins. Studied clutches lacked trophic eggs and tadpoles did not produce foam. Ontogenetic variations in L. knudseni tadpoles are related to size, teeth formulae and body colour. The use of excavated basins for the deposition of foam nests has been reported in several species of the L. pentadactylus group. The absence of trophic eggs and production of foam by the tadpoles differ from other species of the L. pentadactylus group. The tadpole morphology is similar to that described for other species of the group.     

On the life-habits and developmental stages of Nidomyia cana Papp (Diptera,Borboropsidae)

Eggs, second and third instar larvae of the enigmatic species Nidomyia cana, which was discovered most recently from the nests of raptorial birds in southern Hungary, are described. Both egg and larvae show peculiarities among the so-called heleomyzoid flies. Larvae were found in wet vegetable material (mostly pieces of poplar bark) of a buzzard nest and their shape is of a saprophagous type. Females are macro-oviparous, with a maximum of 15 to 17 eggs laid in one batch. Adults live mostly on the surface the of the nest, they copulate there, and they find shelter in the nest itself. No direct contact with adults or nestlings within the nest was observed. It is suggested that overwintering occurs as pupae (pharate adults) underground, beneath the nest. However, if N. cana lives exclusively in the nests of raptors, adults would have difficulties in finding a new nest, and it is probable that they are transferred to new nests attached to the birds.     

Nest architecture in polydomous grass-cutting ants (Acromyrmex balzani)

Acromyrmex balzani is a grass-cutting ant species frequently found in Cerrado areas. However, little is known about the architecture of the polydomous nests of this ant. Fifteen A. balzani nests located in a cerrado region in Botucatu, São Paulo, Brazil, were studied. The polydomous nests were studied in three ways. First, we investigated the architecture in nests moulded with cement and without moulding. Second, we performed an aggressiveness test among workers in different subnests and nests. Third, we excavated the nest and collected the colony to measure the population, verifying the existence or not of a queen in all nests. A cement mould was made of seven nests to permit better visualization of internal structures such as chambers and tunnels. Eight nests were excavated without moulding and white neutral talc was used to highlight the parts of the nests. After excavation, the depth and dimensions (length, width and height) of the chambers were measured. The results showed that the nests had a single entrance hole whose structure consisted of straw and other plant residues in winter. Mounds of loose soil, if present, were found 6–48 cm from the hole. The number of chambers containing fungus ranged from one to five, with the first being found a few centimetres beneath the ground surface (4 cm) and the last up to a maximum depth of 160 cm. The length of the tunnels ranged from 12 to 28 cm. These tunnels were built in a vertical or inclined position, leading to the chambers. No waste chambers were found, with the waste being deposited externally. Additionally, the polydomous nests contained one to eight subnests. In the aggressiveness test, when concolonial workers were confronted, no aggressiveness was observed. In contrast, when allocolonial workers were confronted, there was a high incidence of aggression among them. Excavation of polydomous nests showed only one queen for each polydomous nest, i.e. subnests with a single queen. Our study contributes to a better understanding of the so far unknown nest architecture of the polydomous grass-cutting ant A. balzani.     

Ecology and behaviour of the weaver ant Camponotus (Myrmobrachys) senex

Abstract

Weaver ants use silk produced by their larvae to build their nests. This behaviour is one of the more notable instances of social cooperation in animals; however, there are few studies of Brazilian species. This study investigated the ecology, natural history and behaviour of the weaver ant Camponotus (Myrmobrachys) senex in Brazil and showed that the weaver larvae have a fundamental function in nest building. The nests were always arboreal (one nest/plant), with a round form, beige in colour, and with leaves and shoots adhered to the silk nest. The average size was 34.24 cm and the average weight was 163.87 g; nests contained up to 50,000 individuals and several queens. Fusion and fission of colony parts were observed for C. senex. Worker ants were frequently observed feeding on honeydew, fruits and insects; and defended their territory. We suggest that C. senex larvae could be considered an effective caste, valuable in nest construction.     

Ecology of two Pittas (Pitta soror and Pitta nympha) in limestone forests of South China

The ecology and life history of bird species inhabiting limestone forests, which are under major conservation threats, is currently poorly known. To cover this gap of knowledge, in this study we report for the first time on several aspects of the breeding ecology of the Blue-rumped Pitta (Pitta soror) and the Fairy Pitta (P. nympha) inhabiting two typical limestone forests of south China. The mean density of Fairy Pittas in our study locations was 3.13 ± 2.82 and 1.05 ± 2.09 individuals/km². The Blue-rumped Pitta was common in Nonggang and showed a mean density of 4.67 ± 2.44 individuals/km², yet was absent in the other. We found nine nests between February 2009 and June 2015, including five of the Blue-rumped Pitta and four of the Fairy Pitta. Blue-rumped Pittas laid 4.8 ± 0.4 eggs with a mean fresh mass of 8.10 ± 0.40 g. Fairy Pittas had a clutch size of 5.2 ± 0.45 eggs with a mean fresh mass of 6.03 ± 0.22 g. Blue-rumped and Fairy Pitta parents fed their nestlings 4.0 ± 1.2 times and 3.9 ± 1.5 times per hour, respectively. Earthworms were the most common food item delivered to nestlings by Blue-rumped (93.6%) and Fairy Pitta (91.2%) parents. Blue-rumped Pittas bred successfully in 40% of nests (two of five), whilst in the case of Fairy Pittas nest success reached 75% (three of four). The two Pittas had larger clutch sizes than in southern populations of the same species and also than most other bird species inhabiting limestone forests. This would imply that Pittas show differences in life history traits within limestone ecosystems.     

Observations on mermithid parasitism (Nematoda: Mermithidae) in two species of Lasius ants (Hymenoptera: Formicidae)

The morphological effects of nematode parasitism by Pheromermis myrmecophila were investigated in two species of ants, Lasius flavus and Lasius niger, collected on Clare Island, Ireland. Infected males and queens were found for L. flavus but only infected queens in L. niger. The numbers of nematodes present in each infected specimen were counted and their lengths were measured. Head width, femur length and wing measurements were made for infected and non-infected individuals of both species. In queens, the length of the nematodes decreased as the number per ant increased. When single nematodes were present their mean lengths were significantly greater in L. flavus than in L. niger. In addition to the reduction in wing size for all parasitized specimens, head widths and femur lengths of the queens were significantly different in both species. A log–log graph of radial cell length versus width suggested a linear reduction of wing size.     

Breeding in the gray-headed tody-flycatcher (Aves: Tyrannidae) with comments on geographical variation in reproductive traits within the genus Todirostrum

The gray-headed tody-flycatcher Todirostrum poliocephalum is a passerine endemic to the Atlantic Forest of Brazil. We describe the nest and nesting behaviour of this species and investigate geographical variation in breeding traits in the genus using data from the literature, museum collections, and citizen science projects. We located 21 nests of the gray-headed tody-flycatcher, 13 of which we monitored. Nest height above the ground averaged 3.3 ± 3.4 m (n = 21). Nests were built over a 16.8 ± 5.6-day period (n = 6) by both adults. Clutch sizes ranged from two to three eggs, with a mean of 2.9 ± 0.3 eggs (n = 10). Eggs measured 16.6 ± 0.5 × 12.0 ± 0.5 mm (n = 23) and weighed 1.1 ± 0.1 g (n = 19). Mean incubation period was 17 days (n = 3) and mean nestling period was 15.5 days (n = 2). Apparent reproductive success was 30.8%, with predation being the primary cause of nest failure (46.1%). Mayfield’s reproductive success was 25.9%, and daily survival rates for eggs and nestlings were 0.957 and 0.971, respectively. Clutch sizes increased with latitude, but temperature and precipitation seasonality had very low importance in explaining clutch size variation.