Breeding Pairs Research Articles

Impact of hay mowing on the Stonechat <i>Saxicola torquatus</i> nestling

The impact of hay mowing on nestling Stonechats Saxicola torquatus was describes and quantified through the feeding activity of adults. Three breeding pairs (6 broods) were monitored. Occurrence of invertebrate taxa in the diet of nestling Stonechats was reported. The feeding frequency differs immediately after hay mowing (reduction up to 73%) to go back up after a few days even hunting different prey. The reduction of the feeding frequency does not appear to have affected reproductive success for the breeding pairs at least when the hay mowing takes place in limited and protected areas. The diet composition change with increasing nestling age, spiders and ants increase during the first days.

A case of early breeding of Pied Avocet (<i>Recurvirostra avosetta</i>)

On the 14th of April 2022, during a periodic bird monitoring activity in a wetland area located in the municipality of Mirandola (Moedna), Northern Italy, a breeding pair of Pied Avocets Recurvirostra avosetta, were recorded along with chicks aged approximately 2/3 days old. This is clearly a case of extremely early breeding seeing as, in Italy, Pied Avocets lay eggs from late April to June, based on adequate weather and environmental conditions. As for this specific case, an estimated cause of such anticipated breeding may be the previous very mild Winter months with little rainfall as well as the breeding ground offering shelter from predators.

Changes in Avian Top-Predator Diet in the 21st Century in Northeast (NE) Poland

The White-Tailed Eagle (WTE) Haliaeetus albicilla is a top avian predator that has rapidly increased in numbers and range in large parts of Europe in recent decades. In Poland, over the past 30 years, it has recolonized previously abandoned areas. In 1991, the first breeding pair in a large forest complex, the Augustów Forest (Northeast (NE) Poland), was recorded. In 2022, there were 13 breeding pairs. We analyzed changes in the diet composition of WTE in 2000–2023, divided into three periods: 2000–2005, 2009–2017, and 2018–2023. Throughout the 24 years of study, birds were the most frequently recorded food item, accounting for an average of 58% of food items, followed by fish (34%) and mammals (7%). During the study period, the most numerous food items were the Northern Pike Esox lucius, Coot Fulica atra, Common Bream Abramis brama, Mallard Anas platyrhynchos, and storks Ciconia sp. These species together accounted for 52% of food items. We recorded a long-term increasing share of Northern Pike, storks, and Great Crested Grebe Podiceps cristatus. Opposite changes, with declining frequency, were found for Coots and ducks. The share of the Coot, ducks, and Great Crested Grebe, as well as the total share of food connected with lakes in the WTE’s diet, increased along the growing area of lakes in the territory of the WTE. The proportion of fish in the food did not show a relationship with the increase in the area of lakes, while the most frequently eaten fish species changed. Observed changes in food composition appear related to the settlement of the habitat-diverse areas by individual breeding pairs and changes the availability of main food categories.

The F pilus serves as a conduit for the DNA during conjugation between physically distant bacteria.

Horizontal transfer of F-like plasmids by bacterial conjugation is responsible for disseminating antibiotic resistance and virulence determinants among pathogenic Enterobacteriaceae species, a growing health concern worldwide. Central to this process is the conjugative F pilus, a long extracellular filamentous polymer that extends from the surface of plasmid donor cells, allowing it to probe the environment and make contact with the recipient cell. It is well established that the F pilus can retract to bring mating pair cells in tight contact before DNA transfer. However, whether DNA transfer can occur through the extended pilus has been a subject of active debate. In this study, we use live-cell microscopy to show that while most transfer events occur between cells in direct contact, the F pilus can indeed serve as a conduit for the DNA during transfer between physically distant cells. Our findings enable us to propose a unique model for conjugation that revises our understanding of the DNA transfer mechanism and the dissemination of drug resistance and virulence genes within complex bacterial communities.

Physiological and behavioral effects of hormonal contraceptive treatment in captive, pair-bonded primates (Plecturocebus cupreus).

Hormonal contraception is an effective, reversible tool for managing birth rates in humans and nonhuman animals alike. However, manipulating reproductive hormones has behavioral consequences that can impact social and sexual behavior between conspecifics. First, we studied 18 pairs of nonreproductive titi monkeys (Plecturocebus cupreus) to test the efficacy of a novel method of hormonal contraception (deslorelin acetate implants) on reproductive hormone cycling in females and found significant reductions in urinary estrogens and progestagens among treated females compared to untreated controls. We then studied 35 nonreproductive pairs of coppery titi monkeys (Plecturocebus cupreus) to ascertain whether treating females with one of 2 different forms of hormonal contraception (deslorelin acetate implants (n = 17) or medroxyprogesterone acetate injections (n = 9)) would influence the relationship between pair mates compared to the relationship between untreated females and their vasectomized male mates (n = 9). Over a 5-month period, we found no differences in affiliative behaviors between pairs containing untreated females compared to pairs in which the female was treated with either deslorelin acetate or medroxyprogesterone acetate. Similarly, we found no differences in affiliation between pairs in the 2 treatment groups. This study is the first to examine behavioral consequences of hormonal contraception in a pair-bonding species. The results are encouraging for captive, managed breeding colonies of such social animals, especially those used in behavioral research.

Anthropogenic nesting sites and density of Burrowing Parrot (Cyanoliseus patagonus) in northern Argentinian Patagonia

BackgroundThe expansion of human activities and the development of urban centers are among the main driving forces accounting for the transformation and loss of natural environments. At the same time, and especially for some birds, anthropogenic activity provides new habitat resources. This is the case of the Burrowing Parrot (Cyanoliseus patagonus), in and around Bahía Blanca, a city of ca. 335,000 inhabitants in northern Argentinian Patagonia, where urban and rural quarries and constructed ravines on roadsides are where most of its reproductive activity occurs.MethodsIn this study we monitored anthropogenic nesting sites and estimated the number of breeding pairs from 2018 to 2023 through censuses conducted annually in 23 colonies within a radius of up to 20 km from the communal roost located in the city.ResultsMost of the nesting sites (57%), and the breeding pairs (60 to 80%) were in urban environments, and the remaining in rural areas. Ravines along roadsides and quarries represented the substrate that was most frequently used for nesting. Mean nest density was significantly higher in roadside ravines compared to quarries, and, in turn, higher in urban roadsides compared to rural roadsides.ConclusionAnthropogenic substrates appear as key components for the reproduction of the species, with possible effects on its numbers. The ability of the Burrowing Parrot to reproduce on artificial substrates in the urban environment, and especially the rapid colonization of recently opened sites, represents a new perspective for the conservation and management of its populations.

Mothers in a cooperatively breeding bird increase investment per offspring at the pre-natal stage when they will have more help with post-natal care.

In many cooperative societies, including our own, helpers assist with the post-natal care of breeders' young and may thereby benefit the post-natal development of offspring. Here, we present evidence of a novel mechanism by which such post-natal helping could also have beneficial effects on pre-natal development: By lightening post-natal maternal workloads, helpers may allow mothers to increase their pre-natal investment per offspring. We present the findings of a decade-long study of cooperatively breeding white-browed sparrow-weaver, Plocepasser mahali, societies. Within each social group, reproduction is monopolized by a dominant breeding pair, and non-breeding helpers assist with nestling feeding. Using a within-mother reaction norm approach to formally identify maternal plasticity, we demonstrate that when mothers have more female helpers, they decrease their own post-natal investment per offspring (feed their nestlings at lower rates) but increase their pre-natal investment per offspring (lay larger eggs, which yield heavier hatchlings). That these plastic maternal responses are predicted by female helper number, and not male helper number, implicates the availability of post-natal helping per se as the likely driver (rather than correlated effects of group size), because female helpers feed nestlings at substantially higher rates than males. We term this novel maternal strategy "maternal front-loading" and hypothesize that the expected availability of post-natal help either allows or incentivizes helped mothers to focus maternal investment on the pre-natal phase, to which helpers cannot contribute directly. The potential for post-natal helping to promote pre-natal development further complicates attempts to identify and quantify the fitness consequences of helping.

Natal dispersal, philopatry and cooperative breeding in Eastern Yellow Robin Eopsaltria australis

ABSTRACT Delayed natal dispersal is thought to have evolved in response to survival benefits of philopatry and group formation under environmental and/or demographic constraints, with kin selection subsequently promoting the emergence of cooperative breeding behaviours. We studied sociality and natal and breeding dispersal of a colour-banded population of Eastern Yellow Robin Eopsaltria australis over 10 years to better understand the evolution of facultative cooperative breeding in this long-lived, territorial songbird. Breeding group size averaged 3.08 (range 2–6) adults and 82% of helpers were males. All male young delayed dispersal to help one or both parents (82.1%), another first order relative (12.5%) or other relatives (5.4%) for between one and four years before establishing as a dominant breeder. The social relationships of female helpers was confirmed in only two instances, with the helper being the daughter of the breeding pair. Helpers significantly increased annual productivity, which averaged 1.44 (95% confidence intervals: 1.07–1.81) with no helpers and 2.04 (95% confidence intervals: 1.74–2.34) with helpers present. Male young were highly philopatric; most either inherited the natal territory or budded off a portion of the natal territory, and none dispersed more than one territory away. Most females appeared to disperse further after reaching independence to become floaters. Breeding dispersal was limited to females, who dispersed after either divorce or to avoid incest once a son inherited the territory. These results confirm that Eastern Yellow Robin helpers likely gain indirect fitness benefits from helping.

The impact of helping experience on helper life-history and fitness in a cooperatively breeding bird.

Cooperative breeding occurs when helpers provide alloparental care to the offspring of a breeding pair. One hypothesis of why helping occurs is that helpers gain valuable skills that may increase their own future reproductive success. However, research typically focuses on the effect of helping on short-term measures of reproductive success. Fewer studies have considered how helping affects long-term fitness measures. Here, we analyze how helping experience affects key breeding and fitness-related parameters in the Seychelles warbler (Acrocephalus sechellensis). Importantly, we control for females that have cobred (reproduced as a subordinate by laying an egg within a territory in which they are not a dominant breeder), as they already have experience with direct reproduction. Helping experience had no significant association with any of the metrics considered, except that helpers had an older age at first dominance. Accounting for helping experience, females that had cobred produced more adult offspring (≥1 year) after acquiring dominance and had a higher lifetime reproductive success (LRS) than females that had never cobred. Our results suggest that, in the Seychelles warbler, helping experience alone does not increase the fitness of helpers in any of the metrics considered, and highlights the importance of separating the effects of helping from cobreeding. Our findings also emphasize the importance of analyzing the effect of helping at various life-history stages, as higher short-term fitness may not translate to an overall increase in LRS.

Swimming zygote formation mediated by symmetrically arranged cell fusion sites in the gametes of Chlamydomonas eugametos (Chlorophyceae, Chlorophyta)

SUMMARYThe spatial arrangement of cell fusion sites and eyespots of the gametes in vis‐à‐vis mating pairs of Chlamydomonas eugametos, corresponding to the swimming zygote of Chlamydomonas reinhardtii, were studied using field emission scanning electron microscopy and light microscopy, respectively. After the adhesion of mt+ and mt− gametes, each of which has one eyespot and two flagella elongated from the cell anterior, gamete–gamete fusion occurred at the anterior papilla on the cell apex of each gamete, leading to the formation of a vis‐à‐vis mating pair, indicating that the cell fusion site is arranged symmetrically relative to the flagellar beat plane. In vis‐à‐vis mating pairs, two eyespots could be seen on the same or on opposite sides of the cell. As only the mt+ flagella and eyespot are functional for swimming and phototaxis in the vis‐à‐vis mating pair of C. eugametos, it is suggested that coordinated alignment of the parental gamete flagella and eyespots in the swimming zygote and asymmetric positioning of the gamete mating structure/cell fusion sites, which is prevalent in C. reinhardtii and other chlorophytes, is not necessary for C. eugametos.

Light orientation in the ball-rolling dung beetle, Gymnopleurus sturmi (MacLeay, 1821), in Morocco (Coleoptera: Scarabaeinae: Gymnopleurini)

Summary The ball-rolling dung beetle, Gymnopleurus sturmi, is widely distributed in the Mediterranean Sea Basin. Individuals aggregate to consume dung and only make dung balls for reproduction. The mating pairs formed on dung piles quickly make and roll their ball away from potential competition, mainly from conspecific individuals. We studied the behaviour of G. sturmi in the field, and more particularly the direction of ball rolling after leaving the dung pile. The possible rolling directions were demarcated as 16 numbered sectors oriented according to the four cardinal directions. The experimental results showed that ball rolling was almost always done in a straight line from the food source. The rolling direction was chosen before rolling commenced, during an orientation dance that was similar to that described for Scarabaeini species. In the morning, G. sturmi predominantly rolled their dung balls east-south-east, while in the early afternoon the main rolling direction was south-south-west, shifting to north-north-east at the end of the activity period. The position of the sun seemed to be the major cue for guiding the ball rolling direction, with a rapid readjustment to the initial direction in cases of deviation due to obstacles. We discuss the hypothesis that the opposite rolling directions taken by beetles between the beginning and the end of the afternoon may be due to the switching from direct solar cueing to polarised light cueing near dusk. The results are also discussed in the context of competition.

Best of both worlds? Helpers in a cooperative fairy-wren assist most to breeding pairs that comprise a potential mate and a relative.

In cooperative breeders, individuals forego independent reproduction and help others raise offspring. Helping is proposed to be driven by indirect benefits from raising relatives, and/or direct benefits from raising additional recruits or helping itself. We propose that consideration of social context is also important, in particular the characteristics of the breeding pair: helping may also serve to lighten the workload of-or maintain social bonds with-breeders (e.g. kin, potential mates) who in turn can offer benefits to helpers (e.g. prolonged nepotism, future mating, future production of relatives). Here, we test this hypothesis, while controlling for potential direct and indirect benefits from raising offspring, in purple-crowned fairy-wrens (Malurus coronatus) exhibiting variation in social group composition, and thus, breeder value. We show that helper provisioning rates to the nest were explained by characteristics of breeders that helpers assisted, rather than benefits from raising offspring. The presence of at least one related breeder was a prerequisite to help, but helpers provisioned most if assisting a relative and potential mate. Neglecting to take group composition into account would have led to misinterpretation of our results. A comprehensive understanding of the evolution of cooperative breeding hence requires nuanced consideration of social context.

Emergence of games from ecological trade-offs: longevity changes strategies for extra-pair mating in birds

Each member of a breeding pair benefits if the other does more of the parental investment, so there is scope for behaviours that can be interpreted as both cooperative and competitive games between males and females. Extra-pair mating, widespread among socially monogamous birds, adds extra conflict but also potential opportunity to these social interactions. We analyse an individual-based model of a social environment with simple behavioural strategies where game-like patterns and cooperative outcomes emerge. The model focuses on three evolving traits: female propensity for extra-pair copulations and male investment in territorial behaviour and care. Male traits are reaction norms that use experienced within and extra-pair copulations as information input. We found that female extra-pair mating provided incentives for males to reduce territorial aggression and increase care for offspring. However, when adult survival was higher, male investment in care and territoriality changed from being negatively to positively correlated. This happened because longer life expectancy gave more behavioural opportunities for males, where nest desertion maximises lifetime male fitness when female extra-pair copulation is high. This outcome evolved gradually, with stable periods of intermediate extra-pair mating and low territoriality. These were punctuated by cycles of high extra-pair mating, nest desertion, reduced extra-pair mating and relapse to aggressive territoriality before a new stable phase was established. Each successive trait cycle was faster and smaller, indicating that through evolution of reaction norms, the gene pool has a long history that canalizes the evolution of behaviours, which can be interpreted as emergence and refinement of frequency-dependent games.Significance statementMost birds that mate in monogamous pairs engage in extra-pair copulations. Males of some species invest (in varying proportions) in offspring that are genetically related only to their social female. The great variability of extra-pair mating levels among different species and populations, supported by numerous field studies, indicates that social and ecological factors play a crucial role in shaping the behaviour. We analyse a computer model in which extra-pair mating evolves concurrently with male reproductive investments in territory defence and offspring care and show how common ecological trade-offs may change the social dynamics within a breeding population and lead to the emergence of complex social interactions between males, females and their neighbours.

Lipid storage disease in 4 sibling superb birds-of-paradise (Lophorina superba).

Pedigree analysis, clinical, gross, microscopic, ultrastructural, and lipidomic findings in 4 female superb bird-of-paradise (SBOP, Lophorina superba) siblings led to the diagnosis of a primary inherited glycerolipid storage disease. These birds were the offspring of a related breeding pair (inbreeding coefficient = 0.1797) and are the only known SBOPs to display this constellation of lesions. The birds ranged from 0.75 to 4.3 years of age at the time of death. Two birds were euthanized and 1 died naturally due to the disease, and 1 died of head trauma with no prior clinical signs. Macroscopic findings included hepatomegaly and pallor (4/4), cardiac and renal pallor (2/4), and coelomic effusion (1/4). Microscopic examination found marked tissue distortion due to cytoplasmic lipid vacuoles in hepatocytes (4/4), cardiomyocytes (4/4), renal tubular epithelial cells (4/4), parathyroid gland principal cells (2/2), exocrine pancreatic cells (3/3), and the glandular cells of the ventriculus and proventriculus (3/3). Ultrastructurally, the lipids were deposited in single to coalescing or fused droplets lined by an inconspicuous or discontinuous monolayer membrane. Lipidomic profiling found that the cytoplasmic lipid deposits were primarily composed of triacylglycerols. Future work, including sequencing of the SBOP genome and genotyping, will be required to definitively determine the underlying genetic mechanism of this disease.

Evidence that wolves use cooperative ambush strategies to hunt beavers

Cooperative hunting can confer fitness benefits by increasing foraging efficiency. We documented a breeding pair of wolves in the Greater Voyageurs Ecosystem of Minnesota, USA that appeared to periodically use cooperative ambushing to hunt beavers. The breeding pair primarily chose to wait-in-ambush close to one another (< 65 m) but on different beaver feeding trails, which appears advantageous because: (1) feeding trails are where beavers are most active and vulnerable on land, (2) the probability that the pair encounters a beaver is increased, and (3) either wolf can quickly assist the other in killing a beaver. The cooperative ambush strategy these wolves used appears rare for most social Carnivora but we hypothesize this behavior is widespread in areas of wolf-beaver sympatry. This observation demonstrates that novel insights into the natural history of even well-studied predators are possible when technological advancements are combined with intensive fieldwork.

High Prevalence of Hymenolepis (Rodentolepis) nana in Amateur Breeding Facilities of Chinchillas (Chinchilla lanigera) and Sugar Gliders (Petaurus breviceps) from Italy.

Hymenolepis (Rodentolepis) nana is an enteric tapeworm globally widespread in wild and captive rodents. The survey was carried out in three chinchilla breeding facilities and in one sugar glider breeding facility in Central and Southern Italy. One hundred and four chinchilla fecal pools and 40 sugar glider fecal pools were collected from cages housing breeding pairs or females with their offspring. Fecal samples were examined with a qualitative and quantitative copromicroscopical approach. Hymenolepis eggs were identified based on morphological and morphometrical features, and the average number of eggs per gram (EPG) of feces was estimated. Hymenolepis nana eggs were detected in 39.42% of chinchilla samples with an average of 16.33 EPG; whereas, all of the sugar glider samples tested positive with an average of 454.18 EPG. Neither helminth eggs nor protozoan cysts/oocysts were detected in any of the breeding facilities. The results clearly show a diffuse parasitism in both chinchillas and sugar gliders, and should be taken into consideration given the rising popularity of these two pet species combined with the zoonotic complications presented by H. nana.

Lateralized Movements during the Mating Behavior, Which Are Associated with Sex and Sexual Experience, Increase the Mating Success in Alphitobius diaperinus (Coleoptera: Tenebrionidae).

In the present study, we explored the effects of displacement directionality in mating behavior (i.e., lateralized and non-lateralized movements) on mating success (i.e., copulation occurs) and efficiency (i.e., time length at which copulation is achieved), and its association with sex and sexual experience in A. diaperinus. To do so, we carried out mating experiments and recorded the behavior of the mating pair during the whole mating sequence (i.e., precopulatory and copulatory phases). During the precopulatory phase, independently of sex and sexual experience, all beetles performed non-lateralized (i.e., backside or frontside) approaches; however, only sexually experienced beetles showed lateralized approaches (i.e., right-side and left-side). Notably, experienced males exhibited greater mating success than virgin males. After the approach, both virgin and experienced males displayed lateralized and non-lateralized mounts on the females with distinct mating success. Regardless of their sexual experience, 100% of successful mating attempts were achieved when males mounted from the females' right side. Furthermore, the development of lateralized approaches and mounts reduces the time of mating sequence span compared with non-lateralized behaviors. We highlight the importance of lateralization in mating behavior and sexual experience to achieve higher mating success, addressing a potential learning ability of beetles based on experience.

Exploring NAO influence on waterbirds abundance through hydrological changes in a Mediterranean coastal wetland

Predicting how waterbird populations may respond to climate change is a major challenge for conservation, which could be addressed by understanding the effects of large-scale climate oscillations, such as the North Atlantic Oscillation (NAO), on breeding population size. Here, we explore the relationship between the NAO position and the abundance of waterbird breeding pairs in a protected Mediterranean coastal wetland (Mouth of the Guadalhorce River, Málaga, southern Iberian Peninsula). We found a significant and negative relationship between the winter NAO index and the abundance of grebes (r=-0.72, N=15, p&lt;0.01), rails (r=-0.74, N=15, p&lt;0.01), diving ducks (r=-0.56, N=15, p&lt;0.05) and dabbling ducks (r=-0.54, N=15, p&lt;0.05). Our results suggest that this relation is mediated by the NAO indirect effects on wetland flooded surface via changes in winter precipitation and Mediterranean sea level. These results should be considered to design appropriate environmental management strategies devoted to preventing or mitigating potential deleterious effects of the NAO variability on Mediterranean wetlands ecosystems and preserving their valuable waterbird communities.

Copulatory mechanics of ghost spiders reveals a new self-bracing mechanism in entelegyne spiders.

Spiders evolved a distinctive sperm transfer system, with the male copulatory organs located on the tarsus of the pedipalps. In entelegyne spiders, these organs are usually very complex and consist of various sclerites that not only allow the transfer of the sperm themselves but also provide a mechanical interlock between the male and female genitalia. This interlocking can also involve elements that are not part of the copulatory organ such as the retrolateral tibial apophysis (RTA)-a characteristic of the most diverse group of spiders (RTA clade). The RTA is frequently used for primary locking i.e., the first mechanical engagement between male and female genitalia. Despite its functional importance, some diverse spider lineages have lost the RTA, but evolved an apophysis on the femur instead. It can be hypothesized that this femoral apophysis is a functional surrogate of the RTA during primary locking or possibly serves another function, such as self-bracing, which involves mechanical interaction between male genital structures themselves to stabilize the inserted pedipalp. We tested these hypotheses using ghost spiders of the genus Josa (Anyphaenidae). Our micro-computed tomography data of cryofixed mating pairs show that the primary locking occurs through elements of the copulatory organ itself and that the femoral apophysis does not contact the female genitalia, but hooks to a projection of the copulatory bulb, representing a newly documented self-bracing mechanism for entelegyne spiders. Additionally, we show that the femoral self-bracing apophysis is rather uniform within the genus Josa. This is in contrast to the male genital structures that interact with the female, indicating that the male genital structures of Josa are subject to different selective regimes.

The quality of avian vocal duets can be assessed independently of the spatial separation of signallers

Interactions among groups are often mediated through signals, including coordinated calls such as duets, and the degree of temporal coordination within a group can affect signal efficacy. However, in addition to intrinsic duet quality, the spatial arrangement of callers also affects the timing of calls. So, can listeners discriminate temporal effects caused by intrinsic duet quality compared to spatial arrangement? Such discrimination would allow assessment of quality of duets produced by a pair, as distinct from transient extrinsic spatial effects. To address this issue, we studied experimentally the influence of intrinsic duet quality and spatial arrangement on the efficacy of Australian magpie-lark (Grallina cyanoleuca) vocal duets. Breeding pairs duet at varying distances from each other and to multiple neighbours. Coordinated duets are more effective territorial signals than uncoordinated duets, but it remains unclear whether listeners can discriminate the effects of quality and spatial arrangement. Our playback experiment showed that any deviation from perfect regularity of partners’ notes reduced duet efficacy, but that lack of coordination due to spatial separation (slower tempo and offset of notes) had a lower effect on efficacy than effects due to intrinsic quality (irregularity). Our results therefore provide experimental evidence that the temporal organisation of group vocalisations could signal coalition quality independently of spatial effects.