MOCKINGBIRDS NEED A PLACE TO FLY (original) (raw)
Ornithology
In this study, we documented for the first time singing on the nest (SOTN) in 74% of 65 Northern Mockingbird (Mimus polyglottos) nests that were monitored with continuous-running video cameras (8,353.9 hr sampled). As predicted, higher rates of SOTN significantly decreased daily survival rates of nests. SOTN occurred almost exclusively by females during the egg stage and in 86% (48 of 56) of nests for which we had sampling from the egg stage. While extensive at the population level, the average rate of SOTN per individual was low (5.24 ± 1.24 s SOTN per hour of video sampled). We found mixed support for the hypothesis that SOTN functions in territory maintenance. We found no support for the hypotheses that SOTN functions to coordinate parental care, defend nests, or aid in vocal learning. Given the limited attention SOTN has received and the mostly anecdotal accounts of it, our understanding of its costs and benefits is lacking. We conclude that while individual rates of SOTN are qu...
Use and possible functions of large song repertoires by male Eastern Bluebirds
Journal of Field Ornithology, 2002
Five male Eastern Bluebirds (Sialia sialis) were observed and songs recorded over entire breeding seasons in central Kentucky. Songs consisted of an average of 3.02 notes and the mean time between the beginning of successive songs within a bout was 7.26 s. Most songs (63.7%) given by male bluebirds were low volume, while 14.8% were moderate volume, and 21.5% were high volume. Individual male bluebirds possessed large (x ϭ 59.4) repertoires of song types, and few were shared among two or more males. Singing rates varied among breeding stages, with high rates during the pre-pairing period suggesting that song plays a role in mate attraction. However, male bluebirds also sing during interactions with conspecific males, indicating an aggressive or territorial function, to facilitate the transfer of food to incubating or brooding females, nestlings, and fledglings, and to warn mates, nestlings, or fledglings about the presence of a potential predator. Thus, as reported in an increasing number of species, singing by male bluebirds serves multiple functions.
Nestling Sex Ratios in Two Populations of Northern Mockingbirds
Southeastern Naturalist, 2011
... Acknowledgments. We thank members of the MOXIE lab at Xavier University: Hank Kerschen, Patrick Quinn, Matt Hoffmann, Geoff Putney, Matt Broderick, Dan Schoeff, Amsul Khanal, Whitney Wauligman, Brian Carlson, Molly McCarrick, Kelsey Burns, and Alyssa McMahon. ...
Breeding Adaptations in the Eastern Bluebird
The Condor, 1977
The Eastern Bluebird (Sialia sialis) is a sec-structures built in the abandoned cavities unless an ondary (non-excavating) cavity-nesting spe-obvious disturbance (predation, inclement weather, cies that readily accepts nesting boxes, and conflict with other species) appeared to have many studies (Laskey 1943, Thomas 1946, prompted the move to a new site. I banded 909 bluebirds with a standard aluminum Peakall 1970, White and Woolfenden 1973) band (size 1B) and one to three plastic, colored leg have reported on breeding phenology, clutch bands. Nestlings were banded when 8 to 12 days size, and nesting success in various parts of old. Adult birds were captured with mist nets and its range. In the northern United States some a variety of manual and automatic traps attached to bluebirds are double-brooded; first nests are nest boxes. Although a few birds were caught and banded throughout the breeding period, most unusually begun in early spring and second nests banded adults were captured as soon as possible after are initiated during summer (Peakall 1970). their arrival in March and April. Banding early in the Many bluebird pairs, however, rear only a season was necessary in order to obtain complete single brood in either the spring or the sum-breeding histories because bluebirds may change termer, and do not attempt second nests (pers. ritories and nest sites in early spring (e.g., four different pairs successively occupied a single nest box observ.), perhaps because of a limited num-between 3 Auril and 13 Mav 1976). ber of suitable nest sites (Lack 1968:176, Most bluibirds left the' study ' area in winter; ar-Stewart 1973). rival dates for these birds (migrants) are the dates In this paper I examine bluebird nesting of initial sightings in the study area. An arrival date is not necessarily the date of territory establishment adaptations, particularly those relating to the (males) or date of pair bond formation (males and temporal organization of the breeding season, females). A few bluebirds (non-migrants) wintered and compare nesting performance in year-in and around the study area; I considered their arling and adult birds. To test the hypothesis rival dates as the earliest dates after which I reguthat breeding costs energy and reduces the larly saw them in the breeding areas. Clutch size refers to completed clutches only; I physiological condition of the adults (Rickfollowed Zwickel (1975) in considering clutches comlefs 1974:261), I also compare nesting success plete "if incubation was underway, or in a very few of bluebirds breeding in summer-those who cases, almost certainly underway" provided there was reared a spring brood vs. those who did not. no subsequent increase in the number of eggs present Such a comparison has not been made in in the nest. Date of onset of general laying (GLD) is defined as the earliest date of a season on which studies of other multi-brooded, cavity nesting two or more females laid their first eggs, and the species (Kessel 1957, Summers-Smith 1963, mean GLD date is the average of the general laying Will 1973, Risser 1975). dates for the nine vears of study. I divided the nesting season into three successive periods: spring, intermediate, and summer. The spring period was
The Wilson Journal of Ornithology, 2018
We investigated whether visual cues of a nest predator at the nest site prior to the completion of nest building would induce Eastern Bluebirds (Sialia sialis) to abandon their nesting attempt and switch to another box 10 m away. Upon detecting the onset of nest building in one of the paired boxes, we presented the birds with either a visual predator cue (a rubber black rat snake (Pantherophis obsoletus) or a visual control cue (a model Northern Cardinal (Cardinalis cardinalis) on the active nest box for 15 min and recorded the responses of the resident pair of bluebirds. We returned 1 week later to determine whether the presentation of the snake or cardinal resulted in no change, a switch to the other box, or abandonment of the box pair. Although the bluebirds seemed to respond more negatively to the model snake, we found no significant difference in their propensity to abandon the box pair (vs. remain in one of the paired boxes). We found a similar majority of bluebirds continued to nest in the same box (vs. abandon the effort) in both treatments. Even when we restricted our analysis to the box pair, we found no difference in the propensity to stay vs. switch. Although a larger proportion of bluebirds responded to the snake vs. cardinal model with mobbing, the difference did not reach significance. Bluebirds that mobbed the model were no more likely to abandon the box pair than those that did not mob the model. Although more mobbers abandoned their nest start than did non-mobbers, this difference was not significant. We conclude that the costs of finding a new nest cavity and the close proximity of the boxes provided limited the options of these secondary cavity nesters, even those that engaged in mobbing.
Feeding decisions of eastern bluebirds are situationally influenced by fledgling plumage color
The relative amount of resources that avian parents provide to individual offspring within a brood represents a strategy that can have large effects on reproductive success. We tested whether parental feeding decisions of eastern bluebirds Sialia sialis are influenced by offspring plumage color by presenting pairs of differently colored fledglings side by side and observing how they were provisioned by parents. After a control period, we manipulated blue plumage color so that one sibling in each trial became relatively dark and one became relatively bright. During neither the control nor the experimental periods did either parent consistently feed naturally brighter or experimentally brightened sons more than drab sons. Under specific circumstances, however, both parents directed a higher proportion of their feeding attempts to more brightly colored sons. Paternal feeding attempts to brighter offspring during both the control and experimental periods increased in relation to the brightness of these fledglings relative to their brothers. Maternal feeding decision, on the other hand, were influenced by numerous variables during control and experimental periods including the date of the trial, the difference in mass between fledglings, the feeding behavior of fathers during the trial, the relative investment by fathers during the nestling stage, and the amount of UV chroma in fledgling plumage. Taken together, these results suggest that equal provisioning of offspring is the strategy most commonly adopted by eastern bluebirds but more brightly colored offspring will be fed preferentially when resources for offspring are limited.
UV-blue structural coloration and competition for nestboxes in male eastern bluebirds
Animal Behaviour, 2005
Recent studies suggest that structural plumage coloration can indicate male quality and is used in female mate choice decisions. Whether or not structural coloration functions as a signal in male-male competitive interactions, however, has not been studied. Male eastern bluebirds, Sialia sialis, have brilliant ultraviolet-blue plumage on the head, back, wings and tail that is correlated with both reproductive effort and reproductive success. Bluebirds cannot excavate their own nest cavities, and as a consequence of limited nest sites, often engage in intense competition for nestboxes. We experimentally tested the hypothesis that structural coloration reflects male competitive ability by manipulating the number of available nestboxes. We erected a limited number of nestboxes in early spring and, after birds has established residency in those nestboxes, we added more nestboxes to the study site. We found that the reflective properties of the ultraviolet-blue plumage differed between males that acquired nestboxes early versus late in the spring, indicating that more colourful birds won competitions for access to nest sites. We also found that more colourful males fledged more offspring. These observations support the hypothesis that structural plumage colour is a condition-dependent trait in male eastern bluebirds that could be used to accurately assess the fighting ability of competitors.
The effect of rearing environment on blue structural coloration of eastern bluebirds (Sialia sialis)
Behavioral Ecology and Sociobiology, 2007
We used a brood-size manipulation to test the effect of rearing environment on structural coloration of feathers grown by eastern bluebird (Sialia sialis) nestlings. Ultraviolet (UV)-blue structural coloration has been shown to be sexually selected in this species. Our experimental design took advantage of the growth of UV-blue wing feathers in nestlings that are retained as part of the first nuptial plumage. We cross-fostered nestlings to create enlarged and reduced broods with the purpose of manipulating parental feeding rates and measured the effect on nestling growth and plumage coloration. Brood size influenced feeding rates to offspring, but the effect varied with season. In general, male nestlings reared in reduced broods were fed more often, weighed more, and displayed brighter structural plumage compared to nestlings reared in enlarged broods. Female nestlings appeared to experience less adverse affects of brood enlargement, and we did not detect an effect of brood-size manipulation on the plumage coloration of female nestlings. Measures of plumage coloration in both males and females, however, were correlated to hatching date and nestling mass during feather development. These data provide empirical evidence that environmental quality can influence the development of the blue structural coloration of feathers and that males may be more sensitive to environmental fluctuations than females.