Polygamy in the Marsh Harrier, Circus aeruginosus: Individual Variation in Hunting Performance and Number of Mates

1. Theories postulating that sexual task differentiation may lead to polygamy such that the sex investing the least effort in raising the offspring, engages in simultaneous matings, contrast with polygyny in raptors where the male provides most of the food for its females and nestlings. A field study was undertaken to describe parental effort and success in marsh harriers of different mating status to elucidate this controversy. 2. Data on clutch size and laying date were collected on 421 nests in two Dutch land reclamations, Flevoland and Lauwersmeer. 156 nests were known to have monogamous parents, 30 males had two females and nests. Bigamous males raised on average twice as many fledglings (5.7) than monogamous males (3.0). However, their primary females had more success (3.5) than secondary females (2.3), related to increased nestling mortality in secondary nests. Male fledglings were significantly heavier in primary than in secondary nests. 3. Nest observations made on 22 nests (5 of monogamous, 17 of polygamous males) revealed that daily prey deliveries by males were fewer in mono- than in bigamous males. The latter delivered prey by preference to their primary nests. The prey delivered by a trigamous male were consistently larger than those of a bigamous and monogamous male in the same area. 4. Time budget observations revealed that hunting effort was maximal in the nestling phase (ca 8 hrs foraging per day for all three males observed; at other times of year foraging was reduced in early morning and late afternoon. Net hunting yield (prey brought to nests per hour of hunting) increased in three males with their number (1, 2, or 3) of mates. With progress of the breeding season, male hunting ranges extended further outside the breeding territories and had a great measure of overlap, suggesting that territory quality was not a major factor in male hunting yield. 5. Secondary females participated in provisioning for the nestlings more than primary or monogamy-females, thus compensating for reduced male prey deliveries. 6. Classical polygyny theory addresses the question of female choice: which benefits compensate a secondary female for reduced breeding success by mating with an already paired male? Several hypotheses (enhanced offspring survival, offspring genetic quality, parent chances of future reproduction) are discussed, but evidence is nearly completely lacking. 7. An alternative approach stresses the male's role in the decision process. Males may have more interindividual variation in their capacity to bring food than females in their capacity to lay and incubate eggs. Optimal strategies for males would then range with increasing quality from non-breeding via polyandry and monogamy to polygyny. In species like harriers, non-breeding may be optimal for yearling males with submaximal hunting skills, thus creating a skewed sex ratio forcing some females to accept secondary status as mate of older, high quality males. Polygyny is then associated with slower male than female maturation. The evolution of polyandrous traits in species living isolated in poor environments is likewise explained by this model.

Raptors in the Dutch wetlands

Roofvogels in de Nederlandse wetlands (1995). C. Dijkstra, N. Beemster, M. Zijlstra, M. van Eerden, S. Daan RWS, RDIJ, Flevobericht nr. 381. ISBN 90-369-1147-8. Dit Flevobericht vormt de eindrapportage van het onderzoeksproject " De betekenis van grootschalige wetlands voor roofvogels". De verwerkte gegevens werden verzameld vanaf 1975 tot 1994, voornamelijk in de Flevopolders en de Lauwersmeer. Het rapport heeft betrekking op de interacties tussen roofvogels, het prooiaanbod en het toegepaste beheer in de wetlands. Aantalsvariaties, voortplantingssucces en de jaarlijkse mortaliteit van roofvgels worden besproken. Een belangrijke determinant van genoemde demografische factoren, namelijk de jaagopbrengst, werd onderzocht in relatie tot prooidichtheid en prooibeschikbaarheid. De effecten van verschillende beheersvormen op het prooiaanbod en de roofvogels zijn gekwantificeerd, en een aantal adviezen gericht op een optimaal beheer voor wetland roofvogels worden geformuleerd

Impact of thrombus burden on long-term clinical outcomes in patients with either anterior or non-anterior ST-segment elevation myocardial infarction

Large thrombus burden (LTB) during ST-segment elevation myocardial infarction (STEMI) could translate into worse clinical outcomes. The impact of a LTB in terms of long-term clinical outcomes on different myocardial infarct territories has not yet been fully evaluated. From April 2002 to December 2004, consecutive patients with STEMI undergoing percutaneous coronary intervention with drug eluting stent were evaluated. The study sample was stratified in two groups: anterior STEMI and non-anterior STEMI. LTB was considered as a thrombus larger than or equal to 2-vessel diameters, and small thrombus burden less than 2-vessel diameters. Major adverse cardiac events (MACE) were evaluated at 10-year and survival data were collected up to 15-year. A total of 812 patients were evaluated, 6 patients were excluded due to inadequate angiographic images, 410 (50.9%) had an anterior STEMI and 396 (49.1%) a non-anterior STEMI. Patients with LTB had higher rates of 10-year mortality (aHR 2.27, 95%CI 1.42–3.63; p = 0.001) and 10-year MACE (aHR 1.46, 95%CI 1.03–2.08; p = 0.033) in anterior STEMI, but not in non-anterior STEMI (aHR 0.78, 95%CI 0.49–1.24; p = 0.298; aHR 0.71, 95%CI 0.50–1.02; p = 0.062). LTB was associated with increased 30-day mortality (aHR 5.60, 95%CI 2.49–12.61; p < 0.001) and 30-day MACE (aHR 2.72, 95%CI 1.45–5.08; p = 0.002) in anterior STEMI, but not in non-anterior STEMI (aHR 0.39, 95%CI 0.15–1.06; p = 0.066; aHR 0.67, 95%CI 0.31–1.46; p = 0.316). Beyond 30-day, LTB had no impact on mortality and MACE in both groups. In anterior STEMI, LTB is associated with worse long-term clinical outcomes, this effect was driven by early events. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11239-021-02603-3

Wintering White-tailed Eagles Haliaeetus albicilla in The Netherlands: aspects of habitat scale and quality

The coastal wetlands of The Netherlands have always served as winter haunts for juvenile and immature White-tailed Eagles from breeding populations further north and east. Even as these populations were at their lowest ebb by the 1960s and 1970s, each winter a few individuals showed up, invariably favouring large wetlands with a good supply of wintering, mainly herbivorous, waterfowl. An analysis of the presence of eagles in the wetland Oostvaardersplassen showed that wintering numbers as well as the duration of individual stays increased as a function of the number and biomass of waterbirds present. During the pioneering stage of this newly reclaimed area the dynamic vegetation produced huge seed supplies that attracted vast numbers of herbivorous waterbirds. The increase in eagle numbers in the Oostvaardersplassen reserve preceded the recovery of the northern and eastern breeding populations of White-tailed Eagles, but did not increase any further after reaching a maximum of 3-4 wintering birds, despite the fact that wintering numbers elsewhere in The Netherlands continued to rise in the wake of the increasing breeding population elsewhere in Europe. It is argued that 'core area' Oostvaardersplassen became saturated each winter in the 2000s. Additional eagles reaching The Netherlands spent the winter at alternative sites with smaller food supplies. In 1997-99, new waterbodies were created in the dry border zone of Oostvaardersplassen. The subsequent boost in waterbirds and fish may have triggered- in combination with the presence of undisturbed breeding habitat - the summering, and eventual breeding, of White-tailed Eagles from 2004 onwards. Water management towards improving dynamics in larger wetlands (both estuarine and riverine) may further boost food supplies for waterfowl and, hence, create suitable habitat for White-tailed Eagles elsewhere in The Netherlands

Strong reduction of spectral heterogeneity in gold bipyramids for single-particle and single-molecule plasmon sensing

Single metal nanoparticles are attractive biomolecular sensors. Binding of analyte to a functional particle results in a plasmon shift that can be conveniently monitored in a far-field optical microscope. Heterogeneities in spectral properties of individual particles in an ensemble affect the reliability of a single-particle plasmon sensor, especially when plasmon shifts are monitored in real-time using a fixed irradiation wavelength. We compare the spectral heterogeneity of different plasmon sensor geometries (gold nanospheres, nanorods, and bipyramids) and correlate this to their size and aspect-ratio dispersion. We show that gold bipyramids exhibit a strongly reduced heterogeneity in aspect ratio and plasmon wavelength compared to commonly used gold nanorods. We show that this translates into a significantly improved homogeneity of the response to molecular binding without compromising single-molecule sensitivity

Continuous small-molecule monitoring with a digital single particle switch

The ability to continuously measure concentrations of small molecules is important for biomedical, environmental and industrial monitoring. However, due to their low molecular mass it is difficult to quantify concentrations of such molecules, particularly at low concentrations. Here we describe a small-molecule sensor that is generalizable, sensitive, specific, reversible, and suited for continuous monitoring over long durations. The sensor consists of particles attached to a sensing surface via a double stranded DNA tether. The particles transiently bind to the sensing surface via single molecular affinity interactions and the transient binding is optically detected as digital binding events via the Brownian motion of the particles. The rate of binding events decreases with increasing analyte concentration, because analyte molecules inhibit binding of the tethered particle to the surface. The sensor enables continuous measurements of analyte concentrations due to the reversibility of the inter-molecular bonds and digital read-out of particle motion. We show results for the monitoring of short single-stranded DNA sequences and creatinine, a small-molecule biomarker (113 Da) for kidney function, demonstrating a temporal resolution of a few minutes. The precision of the sensor is determined by the statistics of the digital switching events, which means that the precision is tunable by the number of particles and the measurement time

Continuous Small-Molecule Monitoring with a Digital Single-Particle Switch

The ability to continuously measure concentrations of small molecules is important for biomedical, environmental and industrial monitoring. However, due to their low molecular mass it is difficult to quantify concentrations of such molecules, particularly at low concentrations. Here we describe a small-molecule sensor that is generalizable, sensitive, specific, reversible, and suited for continuous monitoring over long durations. The sensor consists of particles attached to a sensing surface via a double stranded DNA tether. The particles transiently bind to the sensing surface via single molecular affinity interactions and the transient binding is optically detected as digital binding events via the Brownian motion of the particles. The rate of binding events decreases with increasing analyte concentration, because analyte molecules inhibit binding of the tethered particle to the surface. The sensor enables continuous measurements of analyte concentrations due to the reversibility of the inter-molecular bonds and digital read-out of particle motion. We show results for the monitoring of short single-stranded DNA sequences and creatinine, a small-molecule biomarker (113 Da) for kidney function, demonstrating a temporal resolution of a few minutes. The precision of the sensor is determined by the statistics of the digital switching events, which means that the precision is tunable by the number of particles and the measurement time