Individual Nest Site Preferences Do Not Explain Upslope Population Shifts of a Secondary Cavity-Nesting Species

Geographic ranges of plants and animals are shifting due to environmental change. While some species are shifting towards the poles and upslope in elevation, the processes leading to these patterns are not well known. We analyzed 22 years of western bluebird (Sialia mexicana) data from a large nest box network in northern New Mexico at elevations between 1860 m and 2750 m. This population has shifted to higher elevations over time, but whether this is due to changes in nesting behavior and preference for higher elevation within the population or driven by immigration is unclear. We banded adults and nestlings from nest boxes and examined nesting location and elevation for individual birds captured two or more times. Most recaptured birds nested at the same nest boxes in subsequent years, and the number of birds that moved upslope did not significantly differ from the number that moved downslope. Fledglings moved greater distances and elevations than adults, but these movements were not upslope specific. Female fledglings showed greater changes in elevation and distance compared to male fledglings, but again, movements were not consistently upslope. The upslope shift in this population may be due to birds immigrating into the population and not from changes in individual nesting behavior.

Male-built nest volume varies with colony and the timing of the breeding season but not with the nesting-substrate quality and egg production in whiskered terns

Nest building can represent an energetically-costly activity for a variety of animal taxa. Besides, the determinants of within-species variation in the design of nests, notably with respect to natural and sexual selection, are still poorly known although the situation has been partly remedied recently. Based on an observational study, we examined the influence of nesting conditions (nesting-substrate quality, colony, laying date, and year) on the volume of male-built nests and its potential role as a post-mating sexually-selected display in the whiskered tern Chlidonias hybrida, a monogamous species with obligate bi-parental care breeding on unstable aquatic vegetation beds. No relationship was found between the nest volume and the nesting-substrate quality (i.e. nest stability) indicating that the density of white waterlily leaves was large enough when whiskered terns breed. In contrast, building a large nest likely constitutes a selective advantage since nests were larger in less densely populated colonies and for early breeders whatever the year. Since being influenced by nesting conditions, the volume of male-built nests was unlikely to be a sexually selected trait in whiskered terns. The reproductive effort by females (the probability of laying one, two or three eggs, and variation in mean egg volume per clutch) was indeed not correlated with the volume of male-built nests. The fitness consequences of building a large nest are yet to be studied and additional investigations are recommended to better depict the participation of males early during breeding (including notably courtship feeding) and later to chick provisioning.

COLONY COMPOSITION AND BIOMASS OF MACROTERMES GILVUS HAGEN (BLATTODEA: TERMITIDAE) IN INDONESIA

ABSTRACT: There is no study conducted to investigate the composition and biomass of Macrotermes gilvus Hagen in natural forest ecosystem. This study aimed to analyze the colony composition and biomass of M. gilvus Hagen colony in natural forest and to evaluate the need of food of the species as well as factors affecting it. Research was conducted in Yanlappa Sanctuary, Bogor, West Java. Termites were surveyed by collecting individual M. gilvus Hagen from different colony at different size of mound, small (0 – 0.99 m), medium (1- 1.99 m), large (? 2 m) and then were measured the number of individuals, wet and dry body mass, ratio of dry or wet body mass, and the average of biomass. Results indicated that the small mount was dominated by workers, whereas the medium and the large nest was dominated by nymph. Mean of the termite biomass was 936 kg/ha2. Average of termite biomass collected from large mount was 949.8 kg/km2, medium mount was 605.2 kg/ha2 and small mount was about 537.5 kg/ha2. Factor affecting the biomass of subterranean termite M. gilvus Hagen are food source, energy efficiency, predators, and environment. The presence of termite mounds influences natural ecosystem, but that the type of mound plays a crucial role in determining the nature of the effects. ABSTRAK: Kajian tentang komposisi koloni dan biomas anai-anai tanah M. gilvus Hagen di hutan alam belum pernah dilakukan. Kajian ini bertujuan untuk menganalisis komposisi koloni dan biomas koloni anai-anai tanah M. gilvus Hagen di hutan alam dan menganalisa faktor-faktor yang mempengaruhi pemakanannya. Kajian ini dilakukan di Cagar Alam Yanlappa, Bogor, Jawa Barat. Hasil kaji selidik menunjukkan terdapat perbedaan koloni didasarkan pada ukuran tinggi sarang. Sarang kecil (0 – 0.99 m), sarang sedang (1- 1.99 m), dan sarang besar (? 2 m) dan ukuran berat basah, berat kering serta kadar berat basah atau berat kering, dan rata-rata biomas. Hasil kajian menunjukkan bahwa sarang kecil didominasi oleh koloni pekerja, sementara itu sarang serdahana dan sarang besar didominasi oleh koloni nympha. Rata-rata biomas yang ditemukan untuk sarang besar 949.8 kg/ha2, sarang serdahana 605.2 kg/ha2, dan sarang kecil 537.5 kg/ha2. Faktor-faktor yang mempengaruhi biomas anai-anai tanah M. gilvus Hagen adalah makanan, tenaga, pemangsa dan lingkungan. Kehadiran koloni anai-anai mempengaruhi ekosistem semulajadi, tetapi jenis koloni memainkan peranan penting dalam menentukan sifat kesannya.

Collective ventilation in honeybee nests

European honey bees ( Apis mellifera ) live in large congested nest cavities with a single opening that limits passive ventilation. When the local air temperature exceeds a threshold, the nests are actively ventilated by bees fanning their wings at the nest entrance. Here, we show that colonies with relatively large nest entrances use an emergent ventilation strategy where fanning bees self-organize to form groups, separating regions of continuous inflow and outflow. The observed spatio-temporal patterns correlate the air velocity and air temperature along the entrances to the distribution of fanning bees. A mathematical model that couples these variables to known fanning behaviour of individuals recapitulates their collective dynamics. Additionally, the model makes predictions about the temporal stability of the fanning group as a function of the temperature difference between the environment and the nest. Consistent with these predictions, we observe that the fanning groups drift, cling to the entrance boundaries, break-up and reform as the ambient temperature varies over a period of days. Overall, our study shows how honeybees use flow-mediated communication to self-organize into a steady state in fluctuating environments.

Flow-mediated self-organization of ventilation in honeybee nests

European honey bees (Apis mellifera) live in large congested nest cavities with a single opening that limits passive ventilation. These nests are actively ventilated by individual bees which fan their wings at the nest entrance when the local air temperature exceeds a threshold. Here we show that colonies with relatively large nest entrances use an emergent ventilation strategy where fanning bees self-organize to form fanning groups, separating regions of continuous inflow and outflow. The observed spatio-temporal patterns correlate the air velocity and air temperature along the entrances to the distribution of fanning bees. A mathematical model that couples these variables to known fanning behavior of individuals recapitulates their collective dynamics. Additionally, the model makes predictions about the temporal stability of the fanning group as a function of the temperature difference between the environment and the nest. Consistent with these predictions, we observe that the fanning groups drift, cling to the entrance boundaries, break-up and reform as the ambient temperature varies over a period of days. Overall, our study shows how honeybees use flow-mediated communication to self-organize into a steady-state in fluctuating environments.

Hypoxia increases the risk of egg predation in a nest-guarding fish

For fish with parental care, a nest should meet both the oxygenation needs of the eggs and help protect them against predators. While a small nest opening facilitates the latter, it impedes the former and vice versa. We investigated how the presence of potential egg predators in the form of shore crabs Carcinus maenas affects nest building, egg fanning, defensive displays and filial cannibalism of egg-guarding male sand gobies Pomatoschistus minutus under two levels of dissolved oxygen. In the high oxygen treatment, males retained their nest opening size in the presence of crabs, while males in low oxygen built large nest openings both in the absence and presence of crabs, despite the fact that crabs were more likely to successfully intrude into nests with large entrances. Males in low oxygen also fanned more. In the presence of crabs males increased their defensive displays, but while males in high oxygen reduced fanning, males in low oxygen did not. Filial cannibalism was unaffected by treatment. Sand gobies thus prioritize egg ventilation over the protection afforded by small nest openings under hypoxia and adopt defensive behaviour to avert predator attention, even though this does not fully offset the threat from the egg predators.

Brokering a settlement between eagles and industry: sustainable management of large raptors nesting on power infrastructure

SummaryIn the Karoo region of South Africa, eagles nesting on high voltage power pylons are responsible for frequent short-circuits or faults, which reduce the quality of commercial power supply and escalate costs to the country’s energy supplier, Eskom. Between 2002 and 2006 we conducted annual helicopter surveys of eagle nests on 1,400 km of power line and located 139 large nest structures, making up 96 eagle territories occupied by three species: Martial EaglePolemaetus bellicosus(66 pairs), Verreaux’s EagleAquila verreauxii(13 pairs) and Tawny EagleAquila rapax(17 pairs), and detailed 357 pair-years of breeding activity, including 241 breeding attempts. Roost sites and active nests were associated with line faulting, and more so at particular pylon configurations. We developed a three-step management plan to reduce eagle-related faulting while still accommodating eagles on the power lines: (i) all (potentially) problematic nests were relocated from high-risk positions above the power conductors, to specially provided platforms placed below the conductors; (ii) perch deterrents were installed above the conductors on all nest pylons and on high-risk pylons up to 10 structures on both sides of each nest tower; and (iii) the welfare of the eagles was monitored before and after management. In this way, line faulting was reduced on actively managed lines by > 75%, with no obvious deleterious effects on the eagle population. The study revealed that: (i) power lines can support substantial breeding populations of threatened large raptors, (ii) these birds can be a source of commercially significant line faulting, and (iii) nest relocations and perch deterrents are effective in reducing faulting without negatively impacting eagle populations.