Hazel grouse (Bonasa bonasia) pairs during the nonbreeding season: mutual benefits of a cooperative alliance

During the nonbreeding season (autumn and winter), hazel grouse(Bonasa bonasia) males and females associate as loosely boundpairs, not as strongly bound pairs as previously thought. Thesepairs could be considered cooperative alliances, with each membergaining both direct and indirect benefits. The most importantdirect benefit appeared to be mutual vigilance against predators.This benefit was found at two levels: at the level of arborealfeeding sites, two birds could forage faster and farther fromcover than single birds, and at the territory scale, the pairwas together more in dangerous habitats. By foraging fartherfrom cover, two birds could use about 23% more of the preferredfood trees and 9%–10% more of the food available withina territory than a single bird, partially mitigating the costof having two birds feeding on limited winter food in the samespace. Defending a common territory appeared to be a less importantdirect benefit of the alliance because the members of a pairdid not defend the same territory and often associated withneighboring birds of the opposite sex. A future benefit of thealliance was having breeding partners in the spring; this wasmost beneficial for males, as the sex ratio was male biased.Members of the pair were often apart. At arboreal feeding sites,this separation was perhaps because the most preferred trees,black alders (Alnns glutinosa) with the most staminate catkins,were located in areas with the most cover, where one bird maybe safer from predators than two. Members of pairs in more securehabitats were more often with extrapair birds of the oppositesex. This suggested a trade-off; birds in safe habitats mayhave visited potential breeding partners, but birds in dangeroushabitats may have had to remain together, foregoing this option,to increase their survival probability. This social organizationappeared to be an adaptation to surviving in a heterogeneoushabitat, with some of the winter food located in dense coverand some located in more open and dangerous situations.     

Food calling in wild ravens (Corvus corax) revisited: Who is addressed?

Numerous birds and mammals use vocal signals to advertise feeding opportunities but often such signals vary with individual and contextual factors. Non-breeding ravens call at food that is difficult to access, resulting in the attraction of nearby conspecifics. Although callers may benefit from group formation in various ways, we recently found substantial individual variation in food calling. We here explored whether this variation can be partly explained by the social dynamics in raven foraging groups, together with already known effects of age class and sex. Specifically, we expected ravens to respond to the presence or absence of affiliates that could act as cooperative partners in the forthcoming feeding event, that is they should call when other ravens were present but they themselves were alone rather than when they were also in company of an affiliation partner. We observed the vocal behaviour of individually marked wild ravens and, simultaneously, categorized their affiliative behaviour with other ravens in the minutes before experimentally controlled feedings. In line with our prediction, individuals were less likely to produce food-associated calls when they were in close contact with an affiliation partner prior to feeding as compared to when they were alone. Furthermore, sex and age class influenced food calling as females called more often than males and younger birds called more often than adult ravens. In conclusion, these results suggest that ravens attempt to find support from a particular cooperative partner by broadly advertise feeding opportunities via food-associated calls, especially when they have low chances in contest competition due to their age and sex. These findings lend further support to the assumption of raven flocks being structured by social relationships and individual birds flexibly controlling their vocal signalling according to the current flock composition.     

Fitness consequences of helping behavior in the western bluebird

We examined the fitness consequences of helping behavior inthe western bluebird (Sialia mexicana) at Hastings Reservationin Carmel Valley, California, USA, and tested hypotheses forhow helpers benefit from engaging in alloparental behavior.Both juvenile and adult western bluebirds occasionally helpat the nest During a 12 year period, all adult helpers and mostjuvenile helpers were male. Helpers usually fed at nests ofboth their parents and rarely helped when only one parent waspresent. The frequency of pairs with adult helpers was only7%, but nearly one-third of adult males helped among those withboth parents on the study area. At least 28% were breeders whosenests failed. The propensity to help appears to depend uponparental survival, male philopatry, and the breeding successof potential helpers. Feeding rates were not increased at nestswith juvenile helpers, apparendy because breeding males reducedtheir feeding rates. In contrast, adult helpers increased theoverall rates of food delivery to the nest in spite of a reductionin the number of feeding trips made by both male and femaleparents. Helpers did not derive any obvious direct fitness benefitsfrom helping, but they had greater indirect fitness than nonhelpersdue to increases in nestling growth rates and fledging successat their parents' nests. Helpers fledged fewer offspring intheir first nests than did nonhelpers, suggesting that theywere birds with reduced reproductive potential. Although wehave not yet measured the effect of extrapair fertilizationson the fitness benefits of helping, we calculated the differencein fitness between helpers and nonhelpers as a function of thepotential helper's paternity when breeding independently andhis father's paternity in the nest at which he might help. Inconjunction with constraints on breeding and indirect fitnessbenefits, we predict that relatedness of males to the youngin their own as well as their parents' nests will influencehelping behavior in western bluebirds.     

The effect of age at metamorphosis on the transition from larval to adult suspension‐feeding of the slipper limpet Crepidula fornicata

Slipper limpets use different ciliary feeding mechanisms as larvae and adults. Veliger larvae of Crepidula fornicata developed part of the adult feeding apparatus, including ctenidial filaments, neck lobe, and radula, before metamorphosis, but ctenidial feeding did not begin until well after loss of the larval feeding apparatus (velum) at metamorphosis. Earlier initiation of ctenidial feeding by individuals that were older larvae when metamorphosis occurred suggests continued development toward ctenidial feeding during delay of metamorphosis. Early juveniles produced a ciliary current through the mantle cavity and moved the radula in a grasping action before they began to capture algal cells on mucous strands or form a food cord. Either early juveniles could not yet form mucous strands or they delayed their production until development of other necessary structures. The neck canal for transporting food from ctenidium to mouth cannot develop before velar loss. In their first feeding, juveniles fed much like the adults except that the neck canal was less developed and the path of the food cord toward the mouth sometimes varied. As suspension feeders, calyptraeids lack the elaborations of foregut that complicate transition to juvenile feeding for many caenogastropods, but a path for the food cord must develop after velar loss. Why individuals can initiate ctenidial feeding sooner when they are older at metamorphosis is not yet known. The juveniles became sedentary soon after metamorphosis and were not observed to feed by scraping the substratum with the radula, in contrast to the first feeding by juveniles of another calyptraeid species, observed by Montiel et al. ( 2005 ).     

Is mating of copepods associated with increased risk of predation?

In laboratory experiments, we tested whether the cyclopoid copepodCyclops vicinus is more vulnerable to predation by juvenile(young-of-the-year) roach (Rutilus rutilus) and/or larvae ofthe phantom midge Chaoborus flavicans during mating than individualadult copepods of the same species. We also tested whether C.vicinusavoided mating, displayed shorter mating times and/or loweractivity when a predator (Chaoborus) was present, or when exposedto water in which predators (Chaoborus) were previously held.Fish ate the same quantity of pairs in copulation and individualegg-bearing females but significantly fewer females withouteggs. Chaoborus ate similar quantities of pairs and femalesbut fewer males. Pairs in copulation and egg-bearing femaleswere detected earlier by fish than individual non-ovigerousfemales or males, and pairs in copulation were captured mosteasily by fish. Cyclops vicinus mated less often when Chaoboruslarvae were present than in water in which Chaoborus was previouslyheld, or in pure tap water. However, predator presence or exposureto predator-treated water had no effect on (i.e. did not reduce)mating duration. Activity of C.vicinus pairs during copulationwas significantly lower when a predator was present, or in predator-treatedwater, than in pure tap water, and activity of pairs decreasedwith increasing activity of the predator. Although our experimentswere carried out under artificial conditions which cannot betransferred to the complex conditions in the field, they suggestthat mating in copepods is dangerous and that copepods haveevolved particular strategies to reduce the risk of predationduring mating.     

The roles of visual and proprioceptive information during motor program choice in frogs

Previous studies have shown that leopard frogs, Rana pipiens, use tongue prehension to capture small prey and jaw prehension to capture large prey. After hypoglossal nerve transection, the frogs fail to open their mouths when attempting to feed on small prey, but open their mouths and capture large prey. Here, we investigate how visual information about the prey and proprioceptive information from the tongue interact to influence the motor program choice. Using pieces of earthworm of various sizes, we found that Rana exhibits two different behavior patterns based on prey size. The frogs captured the 1.5-cm prey using tongue prehension, whereas 2.0-cm and larger prey were captured using jaw prehension. After hypoglossal transection, the frogs never opened their mouths when they tried to feed on 1.5-cm prey. When feeding on 3.0-cm and larger prey after transection, they always opened their mouths and captured the prey using jaw prehension. When offered 2.0-cm prey, they alternated randomly between opening and not opening the mouth. Therefore, deafferentation changed the pattern of motor program choice at the behavioral border. This implies that afferents from the tongue interact with visual input to influence motor program choice.     

The functions and mechanisms of the protrusible upper jaws of some acanthopterygian fish

Photographs of Pterophyllum and Gasterosteus feeding indicate that they suck food into their mouths by expansion of the buccal and opercular cavities. The premaxillae are protruded as the mouth opens, and remain protruded as it closes. The mechanisms whereby these movements can be performed, by these and by more generalized acanthopterygians, are described. It is shown that the palatines of generalized acanthopterygians are so arranged as to prevent retraction of the premaxillae when the mouth is closed with the buccal cavity expanded.
It is estimated, from rough measurements on a few species, that a teleost cannot suck into its mouth food that is further from its mouth opening than about one-quarter of the length of its head. It is shown that protrusion of the premaxillae can be useful in getting the mouth opening close to food that is to be sucked in, expecially when it is to be taken from the bottom. The possible advantages of closing the mouth with the premaxillae protruded are discussed.
The origin of the acanthopterygian protrusile mechanism is discussed.     

THE PRESENT AND PAST DISTRIBUTION OF THE BALD IBIS IN THE PROVINCE OF THE CAPE OF GOOD HOPE

Tarboton, W. R. 1981. Cooperative breeding and group territoriality in the Black Tit. Ostrich 52:216-225.

In a small, colour-ringed population of Black Tits Parus niger in central Transvaal, 11 of 19 observed breeding units comprised pairs with one to three helper-males. These pairs and groups defended permanent territories, the size of which correlated with the size of the group. There were significantly more territorial disputes during winter when less food was available than in summer. Breeding occurred in summer and the female alone built the nest, incubated the eggs and brooded the young while they were small. During this time she was fed by the alpha male and helper males, although before egg-laying the alpha male prevented helpers from courtship-feeding her. On average, unassisted pairs reared 0,88 young/season whereas pairs with helpers reared 1,55 young/season. However the feeding rate of nestlings of pairs with helpers was not higher than that of unassisted pairs and the number of young reared per group did not correlate with the number of helpers within the group.

The helper system in Black Tits was associated with a skewed sex-ratio (1,7:1 males: females) in the adult population and the data are consistent with the “hopeful reproductive” hypothesis for cooperative breeding.     

Diet influences male-female interactions in the bushcricketRequena verticalis (Orthoptera: Tettigoniidae)

The influence of diet on the courtship roles of male and female Requena verticaliswas investigated in the laboratory. The protein content of available food was found to affect the frequency of mating attempts. Pairs which were fed on a low-protein diet were involved in fewer mating attempts than pairs which were fed on a high-protein diet. Diet also influenced the relative frequencies of male and female rejections. Males rejected their virgin female partners more often than females rejected their male partners when the pairs were kept on a low-protein diet. The opposite was found when the female had mated once before. No difference in the frequency of male and female rejections was found when the pair was kept on a high-protein diet irrespective of the mating status of the female.     

Mate preference for multiple cues: interplay between male and nest size in the sand goby, Pomatoschistus minutus

Female mating preferences are often based on more than one cue.In empirical studies, however, different mate choice cues aretypically treated separately ignoring their possible interactions.In the current work, we studied how male body size and sizeof the male's nest jointly affect mate preferences of femalesand gobies, Pomatoschistus minutus. The females were givena binary choice between males that differed either in body sizeor size of their nest or both. We found that neither body sizenor size of the nest alone affected male attractiveness, buttogether these 2 cues had a significant effect. Specifically,large males were more popular among females when they had alarge nest than when they occupied a small nest. The resultssuggest that if interaction effects between multiple mate choicecues are not considered, there is a danger of ignoring or underestimatingthe importance of these cues in sexual selection by female choice.     

Fitness consequences of selfing and outcrossing in the cestode Schistocephalus solidus

Mixed-mating, that is reproduction by both self-fertilizationand cross-fertilization is common in hermaphroditic parasites.Its maintenance poses, however, a problem for evolutionary biology.The tapeworm Schistocephalus solidus Müller 1776, servedas a model to study experimentally the consequences of selfingand outcrossing in its 2 consecutive intermediate hosts, a copepod(Macrocyclops albidus Jurine) and the three-spined sticklebackfish (Gasterosteus aculeatus). Size-matched tapeworms were allowedto reproduce either alone or in pairs in an in vitro systemthat replaced the definitive bird host's gut. Selfed eggs fromsingletons had a 4 times lower hatching success than outcrossedeggs from pairs. Outcrossed offspring achieved both a higherinfection success and a higher weight in the copepod, and ahigher number of parasites per host in both intermediate hosts,but only under competition. Outcrossed offspring were generallymore successful. If a S. solidus plerocercoid has a partnerin the bird's gut, they should outcross unless they differ insize and thus cannot solve the Hermaphrodite's Dilemma cooperatively.Using microsatellite markers, the proportion of selfed offspringand the total reproductive output of each worm within pairsvarying in mean weight and in weight difference was measured.Worms produced more selfed offspring not only with increasingweight difference as expected but also with decreasing totalweight of the pair. If small worms were selfed, they have alreadypurged deleterious mutations and would thus be better selfersin a year with low parasite density when worms cannot find partners.To maintain this advantage they should self a higher proportionof their eggs even with a partner. Here I review recent exprimentalevidence.     

Do females trade copulations for food? An experimental study on kittiwakes (Rissa tridactyla)

Females of many species copulate more frequently than necessaryto fertilize their eggs despite the potential costs. Severalstudies, particularly on socially monogamous birds, have suggestedthat females obtain immediate material benefits by trading copulationsfor nutrients or other resources. We experimentally tested thishypothesis by manipulating the food resources available to prelayingfemale black-legged kittiwakes (Rissa tridactyla). If femalekittiwakes trade copulations for courtship feeding because theyneed the extra resources, well-fed females (experimental group)should be less willing to copulate compared with females thatare more food limited (control group). Contrary to our predictions,we found that close to the start of laying experimental femalescopulated more frequently with their mate than control females.We also observed that males from the experimental group fedtheir mate at least as often as males from the control group.In experimental pairs, we still observed a positive correlationbetween the rate of copulation and the rate of courtship feeding.Our results thus refute the immediate material benefits hypothesis.Currently available data are consistent with the hypothesisthat prelaying courtship feeding is a form of mating effort.We suggest that the rate of courtship feeding might be a sexuallyselected trait, on which females base decisions about timingand frequency of copulations, but this remains to be tested.     

Dominance and feeding interference in small groups of blackbirds

Dominance and/or interference parameters play a pivotal rolein most ideal free distribution models, but there has beenscant empirical study of the exact manner in which they jointlyoperate. We investigate how foraging effort and success variedamongst individuals of different dominance rankings in groupsof 1-3 wild blackbirds (Turdus merula) attracted to patchesof hidden food. Foraging effort (number of feeding movementsper unit time), as opposed to vigilance tradeoffs, was greaterwhen an individual fed with a subordinate conspecific thanwhen it fed alone, but tended to be less when it fed with adominant individual. Within dyads, changes in foraging effortwere associated with the direction of the dominance relationship,but not the relative difference in dominance rank between thetwo individuals. Similarly, amongst threesomes, top-rankedbirds (but not the lowest-ranked individual) showed higherforaging effort compared to when foraging alone. Top-ranked birds also profited from a greater increase in foraging success(food items per unit effort) than bottom-ranked birds whenfeeding in threesomes than when feeding alone. Dominant birdsshowed increased foraging success, but not effort, after displacinga subordinate. Our results suggest that an individual's foragingeffort is determined by the interplay of group vigilance benefitsand interference costs, the latter being more expensive for subordinate individuals. The foraging success of dominant birdsmay further increase if they use subordinates as food-finders.We discuss the implications of our findings for interferenceparameters in current Ideal Free Distribution models.     

Nestling detectability affects parental feeding preferences in a cavity-nesting bird

In many avian species, nestlings have evolved striking plumage, behaviours and mouth colours to obtain a greater share of parental investment. Studies revealing parental feeding preferences for nestlings with red gapes have proposed that red mouth colour in songbirds can act as a signal of nestling need or condition. Alternative hypotheses suggest that bright nestling mouths in cavity-nesting birds evolved to increase nestling detectability by the parents. We tested whether nestling mouth colour affects parental feeding preferences in great tits, Parus major L. In broods of six young, we experimentally painted mouth gapes and flanges either red or yellow and tested the effect of mouth colour on nestlings' mass gain under two lighting conditions. In nests with high luminosity, there was no significant effect of mouth colour on mass gain. In nests with low luminosity, nestlings with red gapes and flanges gained less mass than nestlings with red gapes and yellow flanges or both yellow gapes and flanges. Our results suggest that, in nests with low luminosity, red mouths decreased nestling detectability to the feeding parents and support the hypothesis that poor luminosity in nesting cavities can select for pale mouths. Overall, our results do not support the hypothesis that red mouth colour signals nestling need or condition to parent great tits.     

The importance of small-scale turbulence in the feeding of herring larvae

Herring larvae form a large, persistent and well-defined aggregateoff southwest Nova Scotia coincident with a region of strongtidally generated turbulence. Our objective is to test the hypothesisthat turbulent, tidally well-mixed regions constitute a preferentialfeeding environment for herring larvae, and are thus the proximatecause for the apparent retention of larvae in these areas. Dimensionalanalysis, coupled with relevant biological parameters and fielddata, are used to derive two non-dimensional numbers from existingpredator-prey encounter models, and to propose a third numberwhich incorporates the minimum encounter rate required for larvalmaintenance. The results of this analysis show that when root-mean-squareturbulent velocities are of the same order of magnitude as theprey velocities, they start to influence encounter rates significantly;and that when turbulent velocities are an order of magnitudegreater than the predator velocities, they dominate the encounterprocess. At reported natural food concentrations, food itemsare on average one order of magnitude away from the larvae'sreach. The importance of turbulence as a mechanism to bringfish larvae closer to their prey is revealed by the findingthat in tidally well-mixed regions herring larvae would requireone order of magnitude less food than their counterparts inthe stratified regions. The model shows that the feeding environmenton the adjacent stratified waters off southwest Nova Scotiais detrimental for herring larvae, and that high mortality wouldbe expected if larvae had to overwinter in this region. Ouranalysis also shows that the growth pattern observed for autumn-spawnedlarvae is explained by the combination of the relevant physicaland biological scales. The overall results of this analysislend support to the hypothesis that turbulent, tidally well-mixedareas provide ideal feeding conditions for herring and may bethe proximate cause for an apparent retention.     

The effect of solicitations on grooming exchanges among female Japanese macaques at Katsuyama

In group-living primates, individuals often exchange grooming with not only kin but also non-kin. We investigated the effect of soliciting behaviors on grooming exchanges in a free-ranging Japanese macaque (Macaca fuscata) group at Katsuyama. In this study, we used a focal animal sampling method, targeting 14 females. Data were collected for 15.75 ± 2.67 (mean ± SD) hours per focal female. We classified female–female pairs into three pair types: kin pairs, affiliated non-kin pairs, and unaffiliated non-kin pairs. Females received grooming more frequently when they solicited after grooming their partners than when they did not solicit in all pair types. In addition, females received grooming less frequently when they did not groom their unaffiliated non-kin partners before soliciting; prior grooming was not needed to receive grooming from kin or affiliated non-kin partners. The degree of grooming reciprocity did not differ according to the frequency with which females in kin or affiliated non-kin pairs solicited after grooming. On the other hand, grooming reciprocity between unaffiliated non-kin females was more balanced when they solicited frequently after grooming, as compared with when they did not. In conclusion, our study suggests that soliciting behaviors promote grooming exchanges in female Japanese macaques.     

Preferred males are not always good providers: female choice and male investment in tree crickets

Female tree crickets (Oecanthus nigricornis) prefer large malesbut do not receive larger glandular courtship gifts from thesemales. This finding is puzzling from both the male and femaleperspectives, because females should prefer males providingmore direct benefits, and because males who provide larger giftsachieve higher insemination success. We tested for differencesin the quality of male secretions and found that larger malesprovided more proteinaceous food gifts than did rivals, whichcould explain why they are preferred by females. The preferencein turn could cause depletion of food gift reserves in favoredmales, because natural remating rates are high and because evena single feeding bout negatively affects glandular stores. Mostintriguingly, we showed that preferred males can adaptivelydecrease the size of courtship food-gifts provided (in orderto conserve gifts for future mating events) when they perceivethat the probability of multiple future mating opportunitiesis high. Thus, the elevated mating rates of preferred males(both before and after a focal mating event) could account forthe small size of their courtship food-gifts.     

Environmental,parental and adaptive variation in egg size of Tengmalm's owls under fluctuating food conditions

We studied egg size variation of Tengmalm's owls in western Finland during 1981–1990. The owls fed on voles whose population fluctuated in a predictable manner: low (1981, 1984, 1987, 1990), increase (1982, 1985, 1988) and peak (1983, 1986, 1986) phases of the cycle occurred every third year. Eggs were largest in the increase phase of the vole cycle, even though that voles were more abundant and egg-laying started earlier in the peak phase than in the increase phase. This suggests that owls invest mostly in egg size when vole abundance increases along with survival chances of offspring. Territory quality and female age had no effects on egg size, but egg size decreased with laying data in the increase phase of the vole cycle. Egg size was significantly positively related to the male age in the increase phase, but the opposite relationship was significant in the peak phase of the vole cycle. The partners of adult males also decreased their egg volume from the increase to the peak phase, whereas the partners of yearling males produced their largest eggs in the peak phase of the vole cycle. This suggests the importance of experience in prevailing food fluctuations. Possibly male Tengmalm's owls can adjust the intensity of courtship feeding not only in relation to the food abundance on their territories at the time of egg laying, but also to the survival prospects of their offspring. Phenotypic plasticity seems to play a substantial role, as the egg size repeatabilities of individual females and partners of individual males were low. Obviously, under cyclic food conditions, predictability and inter-generational trade-offs are important to life history traits.     

Food availability and the male's role in parental care in double-brooded Treecreepers Certhia familiaris

The aim of this work was to examine differences in paternal and maternal care in a double-brooded, monogamous species, the Treecreeper Certhia familiaris, in relation to food availability. As a measure of parental care, we recorded the hourly feeding activity of parents when the nestlings from their first and second breeding attempts were 7 and 12 days old. Feeding frequency of the first brood increased with the age of the nestlings and also with the brood size when 12 days old. While the feeding activities of the females were similar with respect to the first and second broods, the males were less active and failed to provide any food to their nestlings in 15 cases out of 28 second broods. In spite of this, the fledglings from the second broods were heavier than those in the first. Such a pattern of male behaviour was possible without being a disadvantage to the chicks because the food supply increased during the breeding season and the female could provide food for the young alone. Thus paternal care was particularly important in times of poor food supply, i.e. during the first brood, where the extent of these males' activity in feeding the 7-day-old nestlings was positively correlated with the average mass of the nestlings. Our results support the idea that the male of monogamous, altricial bird species often makes important contributions to raising the young, especially during periods when it is difficult for the female to do so alone. Males show flexibility in their pattern of parental care, and male Treecreepers change their contribution to the first and second broods within the same season.     

Age,Experience and Sex – Do Female Bulb Mites Prefer Young Mating Partners?

In species where advancing sire age is associated with decreased progeny fitness, female resistance to mating with old partners can be expected to evolve. In polyandrous species, such resistance may be contingent on female mating experience: virgins should be relatively indiscriminate to ensure egg fertility, whereas non‐virgins can be expected to base their re‐mating decisions on the age of their previous versus potential new partners, and ‘trade‐up’ if previously mated with old males. Here, we tested these predictions using a promiscuous and relatively long‐living bulb mite (Rhizoglyphus robini), in which old sire age is associated with decreased fecundity of daughters. In a fully factorial design, we applied two male treatments, young and old, and three female treatments, virgin, previously mated to an old male and previously mated to a young male. Consistent with earlier studies, we observed a reduced mating success of old males. However, we found no support for attributing this result to female discrimination, as female behavior in response to male mounting attempts was not affected by the age of the suitor, or by its interaction with the age of the female’s previous mate. Interestingly, females were passive during 93% of male mounting attempts observed, suggesting that once they are located by a male, they exert little control over copulation. Old males had lower mate‐searching activity and were less efficient in obtaining matings (lower success rate per mounting attempt), suggesting a decreased mate‐securing ability because of aging. Overall, our results suggest that in bulb mites, male ability to secure mates declines with age, whereas they do not support the prediction that females actively discriminate against old partners.