Elevated testosterone levels and social ranks in female rock hyrax

In mammals, males maintain significantly higher testosterone (T, 'the male hormone') levels than females throughout the year and are typically dominant over females. Our study of the cooperatively breeding rock hyrax (Procavia capensis) demonstrated a distinct exception. In most hyrax social groups that we studied, adult females were at the highest social rank within the group and showed higher than or equal T levels to males. To our knowledge, this is the first reported instance of adult female mammals demonstrating higher T levels than adult males. However, although T levels significantly correlated with rank in males, in females such correlations were not detected, suggesting a more complex interplay between behavior and endocrine factors in this species.     

Do Singing Rock Hyraxes Exploit Conspecific Calls to Gain Attention?

Signal detection theory predicts that signals directed at distant or busy receivers in noisy backgrounds will begin with an alert component, in order to draw attention. Instead of an alert component, however, animals could get the same effect by using an external stimulus. Here we combined observations of free-living rock hyraxes (Procavia capensis) with playback experiments to elucidate the circumstances under which males begin singing. We show that males sing following hyrax pup screams, which elicit a strong response from hyraxes within hearing distance, which are potential receivers. We hypothesize that singers enhance their singing display by exploiting the rarely emitted pup screams. To our knowledge, our findings are the first indication that animals may enhance signal reception by exploiting conspecifics' signals and the differential attention to these signals. We suggest that the utilization of external stimuli by signalers may be widespread, as an adaptive strategy for communication in complex environments.     

Reproductive tactics influence cortisol levels in individual male gray-cheeked mangabeys (Lophocebus albigena)

Concentration of the hormone cortisol is often used as an indicator of stress, and chronically high cortisol levels are often associated with poor health. Among group living animals that compete for resources, agonistic social interactions can be expected to contribute to variation in cortisol levels within and among individuals over time. Reproductive tactics of males can change with individual quality, relatedness, and social structure, and affect cortisol levels. In gray-cheeked mangabey (Lophocebus albigena) groups, male rank is an important factor in social interactions, and males also move between groups while actively competing for females or sneaking copulations. During a 20-month study we observed the social behavior and collected 461 fecal samples from 24 adult male gray-cheeked mangabeys from five groups in Kibale National Park, Uganda. Aggressive interactions and the presence of females at the peak of sexual swelling were associated with elevated cortisol concentrations in all males. Independently, dominant (i.e., highest-ranking) males within groups had higher cortisol concentrations than subordinate males, and immigrant males had higher cortisol concentrations than dominant males.     

Social status does not predict corticosteroid levels in postdispersal male spotted hyenas

In social species with low rates of direct male competition levels of corticosteroids should not correlate with social status. Male spotted hyenas acquire social status by observing strict queuing conventions over many years, and thus levels of male-male aggression are low, and male social status and tenure are closely correlated. In this study, we investigated whether the low rate of direct male competition in spotted hyenas was reflected in fecal corticosteroid levels of adult males in the Serengeti National Park. Also, interactions with dominant females may influence corticosteroid levels of males, and it has been suggested recently that males with a long tenure (high rank) are more stressed by females than males with a short tenure (low rank). We tested whether there is a difference in the likelihood of being aggressively challenged by dominant females between long-tenured and short-tenured males. Short-tenured males were more likely to elicit an aggressive response by females than long-tenured males, but previous work suggests that they also interacted less frequently with females, thus avoiding putting themselves in a potentially stressful situation. Thus, as expected, the comparison of males in three different clans revealed no correlation between social status or tenure and fecal corticosteroid levels. However, males of the largest clan had the highest levels of fecal corticosteroids, possibly reflecting higher rates of social interactions in larger clans.     

A novel song parameter correlates with extra-pair paternity and reflects male longevity

Although elaborate bird song provides one of the prime examples of a trait that evolved under sexual selection, it is still unclear whether females judge the quality of males by attributes of their song and whether these song features honestly signal a male's genetic quality. We measured the ability of male dusky warblers Phylloscopus fuscatus to maintain a high sound amplitude during singing, which probably reflects an individual's physiological limitations. This new measure of singing performance was correlated with male longevity and with extra-pair paternity, indicating that females who copulated with better singers obtained 'good genes' for their offspring. Our findings are consistent with the idea that females assess male quality by subtle differences in their performance during the production of notes, rather than by the quantity or versatility of song. In addition, observations on territorial conflicts indicate that attractive males invest less in competition over territories because they can reproduce via extra-pair paternity.     

Metabolic and respiratory costs of increasing song amplitude in zebra finches

Bird song is a widely used model in the study of animal communication and sexual selection, and several song features have been shown to reflect the quality of the singer. Recent studies have demonstrated that song amplitude may be an honest signal of current condition in males and that females prefer high amplitude songs. In addition, birds raise the amplitude of their songs to communicate in noisy environments. Although it is generally assumed that louder song should be more costly to produce, there has been little empirical evidence to support this assumption. We tested the assumption by measuring oxygen consumption and respiratory patterns in adult male zebra finches (Taeniopygia guttata) singing at different amplitudes in different background noise conditions. As background noise levels increased, birds significantly increased the sound pressure level of their songs. We found that louder songs required significantly greater subsyringeal air sac pressure than quieter songs. Though increased pressure is probably achieved by increasing respiratory muscle activity, these increases did not correlate with measurable increases in oxygen consumption. In addition, we found that oxygen consumption increased in higher background noise, independent of singing behaviour. This observation supports previous research in mammals showing that high levels of environmental noise can induce physiological stress responses. While our study did not find that increasing vocal amplitude increased metabolic costs, further research is needed to determine whether there are other non-metabolic costs of singing louder or costs associated with chronic noise exposure.     

Fecal glucocorticoids reflect socio-ecological and anthropogenic stressors in the lives of wild spotted hyenas

Our aim was to identify natural and anthropogenic influences on the stress physiology of large African carnivores, using wild spotted hyenas (Crocuta crocuta) as model animals. With both longitudinal data from a single social group, and cross-sectional data from multiple groups, we used fecal glucocorticoids (fGC) to examine potential stressors among spotted hyenas. Longitudinal data from adult members of a group living on the edge of the Masai Mara National Reserve, Kenya, revealed that fGC concentrations were elevated during two periods of social upheaval among adults, especially among younger females; however, prey availability, rainfall, and presence of lions did not influence fGC concentrations among hyenas. Our results suggested that anthropogenic disturbance in the form of pastoralist activity, but not tourism, influenced fGC concentrations among adult male hyenas; rising concentrations of fGC among males over 12 years were significantly correlated with increasing human population density along the edge of the group's home range. As hyenas from this social group were frequently exposed to anthropogenic disturbance, we compared fGC concentrations among these hyenas with those obtained concurrently from hyenas living in three other groups undisturbed by pastoralist activity. We found that fGC concentrations from the undisturbed groups were significantly lower than those in the disturbed group, and we were able to rule out tourism and ecological stressors as sources of variation in fGC among the populations. Thus it appears that both social instability and anthropogenic disturbance, but not the ecological variables examined, elevate fGC concentrations and represent stressors for wild spotted hyenas. Further work will be necessary to determine whether interpopulation variation in stress physiology predicts population decline in groups exposed to intensive anthropogenic disturbance.     

Social and environmental factors affecting fecal glucocorticoids in wild, female white-faced capuchins (Cebus capucinus)

Assessing glucocorticoid levels in free-ranging nonhuman primates provides a means to determine the social and environmental stress load for individuals. We investigated the effect of four proximate variables--reproductive state, season, male rank stability, and dominance rank--on the level of fecal glucocorticoids (cortisol metabolites) in eight adult female white-faced capuchin monkeys in Costa Rica. Reproductive state, season, and male rank stability significantly affected fecal glucocorticoids while female dominance rank did not. Cortisol levels were significantly higher in pregnant females as compared with lactating or other reproductive states. Cortisol levels were higher among females during the dry season compared with the wet season, suggesting a metabolic adaptation to maintain homeostasis in drier, hotter conditions. Although unfamiliar males present a greater infanticidal threat than do familiar ones, we found that females experienced higher glucocorticoid levels during male rank instability events, regardless of whether the alpha male role was taken over by a familiar or an unfamiliar male. Our findings provide important benchmark and comparative data for future studies on the variables that affect glucocorticoid levels in this species and other mammals.     

Hormonal correlates of social status and courtship display in the cooperatively lekking lance-tailed manakin

Though cooperative behavior has long been a focus of evolutionary biology, the proximate hormonal mechanisms underlying cooperative interactions remain poorly understood. Lance-tailed manakins (Chiroxiphia lanceolata) are tropical passerines that form long-term male-male partnerships and cooperate in paired male courtship displays. To elucidate patterns of natural hormonal variation in relation to cooperation and reproductive behavior, we examined circulating androgen levels of male lance-tailed manakins in relation to social status, display behavior, and time of year. We found significantly higher circulating androgen levels in alpha-ranked (breeding) males compared to non-alpha adult males in the population. Beta males, which participated in courtship displays but did not copulate, had androgen levels indistinguishable from those of unpaired adult males that never displayed for females, suggesting that an elevated concentration of plasma testosterone in tropical lekking birds may be associated primarily with copulatory behavior or other status-specific traits, and not the performance of courtship display. Androgens decreased throughout the breeding season for males of all status categories. Interestingly, alphas that displayed for females in the observation session prior to sampling had lower androgen levels than alphas that did not display for females. This pattern may result from female discrimination against alpha males at display areas with high levels of social conflict among males, as social disruption is linked to elevated testosterone in many species. However, recent change of a display partner was not related to alpha androgen levels. We discuss alternative explanations and the possible implications of these results, and generate several testable predictions for future investigations.     

Birth season glucocorticoids are related to the presence of infants in sifaka (Propithecus verreauxi)

The responses of plural breeding mammals to environmental stressors are little understood in free-ranging populations, but recent studies of singular breeders suggest that ecological factors and social milieu influence the variable physiological stress responses observed among individuals. Our previous studies examining faecal glucocorticoid (fGC)–behaviour interactions in plural breeding male sifaka (Propithecus verreauxi) show that fGC elevations coincide with specific dispersal events, particularly the eviction of subordinates by resident alpha males. This study examined the utility of fGC assays for assessing the stress responses of male sifaka to demographic changes in the population during the birth season. Analyses were based on 889 faecal samples collected over five birth seasons from 124 adult males residing in 55 different groups at Beza Mahafaly, Madagascar. Results show that fGC levels in males are unrelated to age, residence, group stability or rank, but are significantly and positively correlated with the presence of infants, annual elevations in weekly mean fGC concentrations in males paralleling increasing numbers of infants born annually in the population. These data are the first to show that in seasonal plural breeding species such as sifaka, elevated fGC in males reflects specific events related to reproduction rather than states or social context during the birth season.     

Host sex and ectoparasites choice: preference for, and higher survival on female hosts

1. Sex differences in levels of parasite infection are a common rule in a wide range of mammals, with males usually more susceptible than females. Sex-specific exposure to parasites, e.g. mediated through distinct modes of social aggregation between and within genders, as well as negative relationships between androgen levels and immune defences are thought to play a major role in this pattern. 2. Reproductive female bats live in close association within clusters at maternity roosts, whereas nonbreeding females and males generally occupy solitary roosts. Bats represent therefore an ideal model to study the consequences of sex-specific social and spatial aggregation on parasites' infection strategies. 3. We first compared prevalence and parasite intensities in a host-parasite system comprising closely related species of ectoparasitic mites (Spinturnix spp.) and their hosts, five European bat species. We then compared the level of parasitism between juvenile males and females in mixed colonies of greater and lesser mouse-eared bats Myotis myotis and M. blythii. Prevalence was higher in adult females than in adult males stemming from colonial aggregations in all five studied species. Parasite intensity was significantly higher in females in three of the five species studied. No difference in prevalence and mite numbers was found between male and female juveniles in colonial roosts. 4. To assess whether observed sex-biased parasitism results from differences in host exposure only, or, alternatively, from an active, selected choice made by the parasite, we performed lab experiments on short-term preferences and long-term survival of parasites on male and female Myotis daubentoni. When confronted with adult males and females, parasites preferentially selected female hosts, whereas no choice differences were observed between adult females and subadult males. Finally, we found significantly higher parasite survival on adult females compared with adult males. 5. Our study shows that social and spatial aggregation favours sex-biased parasitism that could be a mere consequence of an active and adaptive parasite choice for the more profitable host.     

Low-ranking individuals present high and unstable fecal cortisol levels in provisioned free-ranging adult male rhesus macaques (<Emphasis Type="Italic">Macaca mulatta</Emphasis>) during the birth season in a mountain area of northern China

Social hierarchy commonly exists in animal societies, affecting both the endocrine functioning and the behavior of animals. In nonhuman primates, the relationship between social rank and cortisol levels varies across species and even within species. Here, we assessed the relationships between social rank and fecal cortisol levels in adult male Taihangshan macaques (rhesus macaques, Macaca mulatta tcheliensis) from the provisioned, free-ranging Wulongkou-2 (WLK-2) group inhabiting Wulongkou Scenic Area, Jiyuan, China. From March to May 2014, we recorded 195 agonistic behaviors and collected 54 fresh fecal samples from eight adult male Taihangshan macaques. Males were assigned a social rank according to an agonistic behavior matrix, and enzyme-linked immunosorbent assay was then used to measure the cortisol concentration in the fecal samples. We found that social rank among the eight male Taihangshan macaques in WLK-2 group followed a strict linear hierarchy, and that fecal cortisol levels were significantly higher and more variable in low-ranking males than in more dominant individuals. Age was not significantly associated with social rank or fecal cortisol levels. Our results suggest that social rank and maintenance of the social hierarchy within the WLK-2 group is a chronic stressor, with low-ranking males maintaining heightened stress levels and enlarged reactive scope relative to dominant males. This provides new support for the theory that social environment can influence endocrine functioning.     

INTERACTIONS OF SINGING HUMPBACK WHALES WITH OTHER MALES

Two non-mutually exclusive hypotheses on the function of the humpback whale song are: (1) it attracts females to the male singer; (2) it is a male-male display, that may order status. To evaluate these, from 24 January-13 April 1997 off Maui, Hawaii, 42 singers were located, audio-recorded, photo-identified and monitored for interactions with other whales. Whales that joined singers were biopsy sampled for molecular determination of sex. In 76% (32 of 42) of the interactions, a lone non-singing adult joined the singer. In the remainder, singers stopped singing and joined a nearby group or accompanied other whales. In 81% (26 of 32) instances where a lone adult joined a singer, the pair split again within minutes; otherwise a group formed. In one such group the pair became a trio and eventually joined a competitive group. Behavior in joining/splitting interactions ranged from a single pass-by, to surface activity such as tail lobs and breaches. The sex of 22 joiners was determined: 14 genetically and eight behaviorally. All were males. Humpback whale song preceded, and at times followed, male-male interactions of variable duration and agonistic level in and around the breeding season. If considered within the context of a proposed dominance polygyny mating system, these observations appear to support speculation that the song may function in male social ordering.     

High levels of infant handling by adult males in Rwenzori Angolan colobus (Colobus angolensis ruwenzorii) compared to two closely related species,C. guereza and C. vellerosus

Infant handling (holding or carrying) by adult males is rare in mammals; however, high levels have been reported in some primates. Though infant handling is a costly behaviour, there are many benefits that male handlers can accrue. Infant handling by males is most conspicuous in platyrrhines and tends to be uncommon in catarrhines. In the latter species, research on male–infant interactions has focused on low-cost behaviours, such as proximity and grooming. However, to better understand the evolution of infant handling by males, more data on its occurrence across the Primate order are essential, even in species where it is relatively uncommon. We compare the occurrence of infant handling by males in three closely related species of catarrhine: Colobus vellerosus, C. guereza, and C. angolensis ruwenzorii. We collected focal animal samples on infants to quantify infant handling rates and durations, and found that adult male C. a. ruwenzorii handled infants much more frequently and for much longer than males in the other two species. We discuss how C. a. ruwenzorii’s unique social organization may explain high levels of infant handling by adult males in this species. More long-term and detailed comparisons of infant handling across species and populations will shed light on how sociality has shaped the evolution of this behaviour in the Primate order.

     

Female presence affects male behavior and testosterone levels in the European starling (Sturnus vulgaris)

In this study, we confronted individually housed male European starlings (Sturnus vulgaris) with a female conspecific for 60 min to study the consequences on behavior and plasma testosterone (T) concentrations. Control males experienced a similar procedure, the only difference being that they were tested in the absence of a female. Female presence significantly affected both behavior and plasma T levels of male starlings. Experimental males spent significantly more time singing in the nest box and flew significantly more into the nest box with green nesting material during female presentations than during control periods. Control males never showed these mate attraction behaviors. In total 5 of the 16 experimental males did not respond behaviorally to the female stimulus bird (NR males). In contrast to T levels of control males, plasma T concentrations of both experimental males that did respond to the female (R males) and of NR males (which only perceived the female stimulus) were positively influenced by female presentation. The time spent singing in the nest box by experimental males (R and NR males combined) during female presence tended to be positively correlated with changes in plasma T levels. Finally, before introduction of a female, plasma T levels of R males were significantly higher than those of NR males indicating that individually housed males respond to the presence of a female conspecific by increasing their mate attraction behaviors only when a threshold plasma T concentration has been reached.     

Low Testosterone Correlates with Delayed Development in Male Orangutans

Male orangutans (Pongo spp.) display an unusual characteristic for mammals in that some adult males advance quickly to full secondary sexual development while others can remain in an adolescent-like form for a decade or more past the age of sexual maturity. Remarkably little is understood about how and why differences in developmental timing occur. While fully-developed males are known to produce higher androgen levels than arrested males, the longer-term role of steroid hormones in male life history variation has not been examined. We examined variation in testosterone and cortisol production among 18 fully-developed (“flanged”) male orangutans in U.S. captive facilities. Our study revealed that while testosterone levels did not vary significantly according to current age, housing condition, and species origin, males that had undergone precocious development had higher testosterone levels than males that had experienced developmental arrest. While androgen variation had previously been viewed as a state-dependent characteristic of male developmental status, our study reveals that differences in the physiology of early and late developing males are detectable long past the developmental transition and may instead be trait-level characteristics associated with a male’s life history strategy. Further studies are needed to determine how early in life differences in testosterone levels emerge and what consequences this variation may have for male behavioral strategies.     

Effect of photoperiod and temperature on indicators of immunity and wellbeing of endangered golden mahseer (Tor putitora) broodstock

Recently, we reported the possibility of successfully inducing captive maturation and spawning in golden mahseer through photothermal manipulation. Subsequently, we felt that it was imperative to understand the impact of these environmental manipulations on immunity, stress response, antioxidant potential, and general well-being of adult mahseer to develop a healthy broodstock. For this purpose, two experiments were carried out with changes in photoperiod (experiment I) and temperature (experiment II). In experiment I, random groups of adult female and male Tor putitora were subjected to three photoperiods (8L:16D, 12L:12D and 16L:8D) for 100 days. Decreasing levels of plasma melatonin with increasing photoperiod confirmed the physiological significance of different light-dark conditions in mahseer brooders. In terms of stress, plasma cortisol levels showed a linear increase with decreasing light duration in both males and females. Similarly, the level of thiobarbituric acid reactive substances was also significantly higher in males kept at 8L:16D. Plasma concentration of total immunoglobulins was found reduced in female brooders at 8L:16D, but this was not evident in males. In females, total antioxidants were found significantly elevated at 12L:12D. On the contrary, superoxide dismutase activity was lower at 12L:12D in females. The photoperiod has substantially influenced the plasma total protein and albumin levels in males. In experiment II, random groups of adult T. putitora were reared at ambient (21.2 ± 1.4 °C) or elevated temperature (23.7 ± 1.3 °C) groups for 121 days. The higher temperature was found to significantly decrease lysozyme, myeloperoxidase, and anti-protease activities in female mahseer brooders. However, total immunoglobulin levels were reduced significantly at elevated temperature both in males and females. No other temperature-related significant changes were observed in antioxidant potential, anti-oxidative enzymes or well-being related indices.     

The multiple functions of male song within the humpback whale (Megaptera novaeangliae) mating system: review,evaluation, and synthesis

Humpback whales (Megaptera novaeangliae) are seasonal breeders, annually migrating from high‐latitude summer feeding grounds to low‐latitude winter breeding grounds. The social matrix on the winter grounds is a loose network of interacting individuals and groups and notably includes lone males that produce long bouts of complex song that collectively yield an asynchronous chorus. Occasionally, a male will sing while accompanying other whales. Despite a wealth of knowledge about the social matrix, the full characterization of the mating system remains unresolved, without any firm consensus, as does the function of song within that system. Here, I consider and critically analyse three proposed functions of song that have received the most attention in the literature: female attraction to individual singers, determining or facilitating male–male interactions, and attracting females to a male aggregation within the context of a lekking system. Female attraction suggests that humpback song is an advertisement and invitation to females, but field observations and song playback studies reveal that female visits to individual singers are virtually absent. Other observations suggest instead that females might convey their presence to singers (or to other males) through the percussive sounds of flipper or tail slapping or possibly through vocalizations. There is some evidence for male–male interactions, both dominance and affiliative: visits to singers are almost always other lone males not singing at that time. The joiner may be seeking a coalition with the singer to engage cooperatively in attempts to obtain females, or may be seeking to disrupt the song or to affirm his dominance. Some observations support one or the other intent. However, other observations, in part based on the brevity of most pairings, suggest that the joiner is prospecting, seeking to determine whether the singer is accompanying a female, and if not soon departs. In the lekking hypothesis, the aggregation of vocalizing males on a winter ground and the visits there by non‐maternal females apparently for mating meet the fundamental definition of a lekking system and its role though communal display in attracting females to the aggregation, although not to an individual singer. Communal singing is viewed as a form of by‐product mutualism in which individuals benefit one another as incidental consequences of their own selfish actions. Possibly, communal singing may also act to stimulate female receptivity. Thus, there are both limitations and merit in all three proposals. Full consideration of song as serving multiple functions is therefore necessary to understand its role in the mating system and the forces acting on the evolution of song. I suggest that song may be the prime vector recruiting colonists to new winter grounds pioneered by vagrant males as population pressures increase or as former winter grounds become unavailable or undesirable, with such instances documented relatively recently. Speculatively, song may have evolved historically as an aggregating call during the dynamic ocean conditions and resulting habitat uncertainties in the late Miocene–early Pliocene epochs when Megaptera began to proliferate. Early song may have been comprised of simpler precursor sounds that through natural selection and ritualization evolved into complex song.     

Behavioral phenotypes persist after gonadal steroid manipulation in white-throated sparrows

White-throated sparrows (Zonotrichia albicollis) exhibit a behavioral polymorphism that segregates with a plumage marker. Individuals with a white stripe (WS) on the crown engage in an aggressive strategy that involves more singing, whereas individuals with a tan stripe (TS) sing less and engage in more parental care. Previous work has shown that plasma levels of gonadal steroids differ between the morphs in both sexes, suggesting a hormonal mechanism for the polymorphic behavior in this species. Here, we eliminated morph differences in plasma levels of testosterone (T) in males and estradiol (E2) in females in order to test whether morph differences in behavior would be similarly eliminated. Males and females in non-breeding condition were treated with T or E2, respectively, so that plasma levels in the treated groups were high and equal between the WS and TS morphs. We found that despite hormone treatment, WS and TS birds differed with respect to singing behavior. WS males sang more in response to song playback than did TS males, and WS females exhibited more spontaneous song than TS females. We also found that WS males gave more chip calls, which are often used in contexts of territorial aggression. Overall, these results suggest that WS birds engage in more territorial vocalization, particularly song, than do TS birds, even when T or E2 levels are experimentally equalized. This behavioral difference may therefore be driven by other factors, such as steroid metabolism, receptor expression or function, or steroid-independent neurotransmitter systems.     

Age related variation in male–male relationships in wild spider monkeys (Ateles geoffroyi yucatanensis)

In social organizations characterized by male philopatry, social relationships between males are argued to be the strongest. Little is known about the social relationships of philopatric male spider monkeys. To address this limitation, we investigated social relationships among individually recognized wild adult male spider monkeys from two well-habituated communities in the Yucatan Peninsula, Mexico, focusing on affiliative behaviors important in regulating male social relationships, including grooming, embracing, arm-wrapping, and grappling. We examined whether behaviors were reciprocated between male partners and whether age was a factor in how the behaviors were distributed or reciprocated, by examining differences between younger adult males (<10 years) and older adult males (≥14 years). Although we found evidence that affiliative behaviors were overall reciprocated between spider monkey adult males, there were pronounced differences in the interactions depending on their relative age. Reciprocation in grooming and embraces between same-age males suggests their relationships are valuable to both partners. Among different-age dyads, younger males gave more embraces than they received, were the initiators of grappling and arm-wrapped more often than with same-age males, suggesting relationships between younger and older males are more risky. This confirms that younger males are attracted to older males, probably because they value relationships with older males more than the reverse, but they are also at risk.