利用多旋翼微型飞行器监测天山地区高山兀鹫繁殖简报

高山兀鹫(Gyps himalayensis)喜在山崖绝壁上营巢,海拔2 400~4 800 m的野外高空作业攀爬危险,观察难度较大。2014年4~9月,笔者在新疆天山中段尝试用国产遥控多旋翼微型飞行器寻找和拍摄高山兀鹫巢穴,结合路线搜索法和行为扫描法,进行栖息地调查、巢数统计、巢材分析,以及窝卵(雏)数、雏鸟生长与发育、繁殖周期、食性及食物分析。在7个地点的14个巢区的调查统计表明,高山兀鹫喜欢在朝南的崖壁上集群营巢(78.6%朝南,n=112),最长的一个繁殖地绵延7.3 km,距另外一个较近的巢区约47 km。巢材以禾草为主,如早熟禾(Poa spp.)、针茅(Stipa spp.)、老芒麦(Elymus sibiricus)等,缺乏粗大枝条。高山兀鹫1~2月产卵,窝卵数为1枚(n=21),整个繁殖周期长达8~9个月(1~10月份)。     

甘薯天蛾的交配行为及其影响因素

了解甘薯天蛾的交配行为习性是人工大量繁殖甘薯天蛾的关键之一。在室内条件下,采用行为生态学的研究方法,系统观察了甘薯天蛾的交配行为习性,对不同雌雄性比、空间环境和光照周期下甘薯天蛾的交配行为规律和交配率进行了研究。结果表明：甘薯天蛾在羽化后第2天开始交配,在第2天交配率最高,达到53.9%,随后交配率逐步降低;雌蛾只交配1次。在一天中,成虫交配时间发生在22:00—5:00,高峰期在22:00—24:00和3:00—5:00。雌雄性比、光照周期和空间环境对甘薯天蛾的交配成功率具有明显的影响,在全黑暗和全光照条件下不会发生交配行为,表明其交配行为发生需要一定光照和暗期的刺激;当雌雄性比为1∶1时交配率最高,为54.7%,在其他性比条件下甘薯天蛾的交配率明显降低;在空间规格为1.20 m×0.60 m×0.35 m和2.00 m×2.00 m×2.00 m时能够顺利交配,其交配成功率>62.0%。在人工繁殖甘薯天蛾的生产过程中,建议单对放养,采取适当的交配空间和应用自然光照周期营造条件将取得较好的交配产卵效果。     

核桃举肢蛾田间羽化节律与交配行为

[目的]核桃举肢蛾Atrijuglans hetaohei Yang是核桃重要的蛀果害虫,通过明确核桃举肢蛾野外田间的羽化节律和交配行为,为核桃举肢蛾的性信息素研究提供基础。[方法]本研究在田间条件下观察了核桃举肢蛾的羽化节律和交配行为等生殖活动规律。[结果]核桃举肢蛾需要历时45~60 min完成羽化行为,成虫羽化高峰期集中在5月下旬至6月上旬,具有明显的昼夜节律,上午10:00-13:00为羽化高峰期,高峰期的羽化数占整日羽化量的73.99%。雌雄虫比率接近1:1,其中羽化前期,雄虫羽化量比雌虫多8.67%,降雨降温天气条件可影响其羽化进程。成虫上午、中午和夜晚静伏不动,下午16:00至傍晚19:30成虫活跃,频繁爬行、飞翔。在此期间,观察到雌虫出现求偶召唤状态及交配行为。雌虫分散产卵,平均产卵量为22.6粒。[结论]本研究揭示了核桃举肢蛾野外田间的羽化节律和成虫生殖活动行为,雌虫出现求偶、交配行为的时间、状态与环境条件。     

云南新平哀牢山红瘰疣螈的陆地求偶交配行为模式

红瘰疣螈Tylototriton shanjing为云南山地环境中典型的有尾两栖类,其求偶交配行为模式尚未被系统研究。2013—2014年对云南省新平县哀牢山繁殖期红瘰疣螈在陆地环境中的求偶交配模式进行了观察。研究结果显示,红瘰疣螈的求偶交配行为是按照一定时序进行的,整个过程由定位、静止展示、劝导展示和精子转移4个阶段组成。在求偶交配中雄性个体行为包括:警戒、追逐、阻拦、蹑行、嗅探、轻推、诱导、扇尾、侧行和产精包等类型。雌性个体的行为包括离开、静止、跟随、纳精包等类型。雄性行为较雌性复杂,雄性在求偶交配行为过程中占据主动。雌雄的识别主要以视觉为主,整个求偶交配过程中无抱握行为,雄性尾部的运动也比较单一,这些行为的变化可能是对在陆地求偶交配的适应。     

圈养普氏野马繁殖期的昼间行为时间分配

2011年4月~8月,在新疆野马繁育中心采用目标动物取样法,研究了圈养普氏野马(Equus ferus przewalskii)繁殖期昼间行为时间分配。结果表明:(1)雌雄普氏野马繁殖期采食、饮水和站立行为差异不显著(P0.05),而休息、运动、修饰和其他行为均表现出显著性差异(P0.05)。其中,雄马的休息时间、修饰时间显著低于雌马,运动时间和其他行为时间显著高于雌马。(2)雌雄个体繁殖期除运动、修饰和其他行为节律存在显著差异外(P0.05),其余行为节律则表现出一定的同步性。(3)雌雄野马繁殖期内昼间交配次数比较少,且同一家族群内雌马各自参与交配的日期基本不会重叠,同一天内,雄马与群内两匹以上雌马均有交配的现象十分罕见。     

光周期变化对毛健夜蛾交配和产卵的影响

【目的】毛健夜蛾Brithys crini(Fabricius)可为害葱莲Zephyranthes candida等石蒜科绿化植物,前期研究表明不同光周期对其交配和产卵节律行为及交配率和产卵量均有显著影响。本实验期望探明间歇光照等复杂光照条件对毛健夜蛾交配和产卵的影响。【方法】在光照培养箱条件下(光源为白色日光灯,光照强度约为500 lx),观察了间歇光照长度(20,10,5,1和0 min)、暗期位点(D10:00-22:00,D12:00-24:00,D14:00-02:00和D16:00-04:00)和非24 h光暗循环(4L∶4D,8L∶8D,24L∶24D和48L∶48D)3种光照条件下毛键夜蛾成虫交配及产卵行为。【结果】间歇光照长度为20,10,5,1和0 min时,成虫交配数分别为0,3,10,14和11对,配对数分别为25,29,31,39和26对;间歇光照长度为20和10 min时,交配数与对照组差异显著;10,5,1和0 min时已交配单雌产卵量差异不显著(分别为354.67,322.30,339.57和310.45粒)。暗期位点为D10:00-22:00,D12:00-24:00,D14:00-02:00和D16:00-04:00时,成虫交配数分别为13,18,15和12对,配对数分别为16,19,17和16对,交配数差异不显著;已交配单雌产卵量差异不显著(分别为516.15,527.28,495.53和458.50粒);交配起始时间、交配高峰时间和产卵起始时间、产卵高峰因暗期位点不同而异。非24 h光暗循环(4L∶4D,8L∶8D,24L∶24D和48L∶48D)条件下成虫交配数分别为16,15,14和14对,配对数分别为18,16,14和16对,交配数差异不显著;已交配单雌产卵量差异显著(分别为590.56,559.67,497.21和419.29粒)。【结论】这些结果显示毛健夜蛾交配和产卵行为主要发生在暗期,暗期短于40 min时不能发生交配行为,暗期位点和长度对交配和产卵行为有影响。     

酪蝇交配行为和能力

在(27±1)℃,光周期L∶D=12∶12的条件下对酪蝇Piophila casei L.交配行为及能力进行了研究。结果表明,雌虫在羽化1min后即可交配,而雄虫在羽化30min后进行交配。进一步观察结果表明,羽化后80min的两性成虫交配率最高(90%),成虫一天之中的交配高峰期出现在10∶00—11∶00,次高峰出现在11∶00—12∶00。两性交配持续时间从4～9min不等,以5min为最多(43.3%),6min次之(23.3%)。一般情况下,雌虫一生只交配1次,雄虫从1～7次不等,但以2次为最多(45%),3次的次之(20%)。     

高原山鹑越冬后期日节律及行为观察

2010年3～4月,在四川省稻城县对高原山鹑Perdix hodgsoniae越冬后期的昼间行为进行了初步观察,包括其活动规律、时间分配、日行为节律、群体解散过程、社群行为、交配行为、天敌及反捕行为等,并与近缘种及相关研究进行了对比。其活动时间分配如下:取食占69.31%±2.33%,休整占20.06%±2.26%,防卫占7.10%±0.71%,移动占3.53%±0.47%。每日10:00～14:00、15:00～16:00为高原山鹑取食行为的高峰,清晨、傍晚以及中午14:00～15:00为取食行为的低谷;休整行为的节律与之相反,清晨和傍晚是休整的高峰,中午为小高峰;清晨、傍晚及中午14:00～15:00防卫行为的频率稍高。高原山鹑群体大小为(11.39±0.97)只(1～30,n=41),群体间具有领域行为,相互间有攻击行为。群体自3月末开始逐渐解散。最早观察到的交配行为是在3月22日,多发生在上午和中午。     

意大利蝗交配行为观察

通过昆虫行为观测仪与室外饲养观察,分析意大利蝗Calliptamus italicus的交配行为,阐明交配经历和温度对意大利蝗交配持续时间的影响。结果发现:(1)意大利蝗的交配行为包括相遇和交配两个阶段。相遇行为包括避让、打斗和交配3种类型,其中打斗多发生在雄雄相遇、雄虫与一对正在交配成虫相遇情况。避让和交配则多发生在雌雌相遇、雌雄相遇、雌虫与一对正在交配成虫相遇情况。雄虫在交配过程中占据主动。意大利蝗的交配行为包括曲腹、爬背、抱对和交配4个过程,平均时间为11.25±1.40 min。(2)雌雄虫初次交配的持续时间(12.88±0.67 min)显著长于雌雄虫均有交配经历的时间(10.47±0.39 min)(P0.05);初次交配雌虫和有交配经历雄虫的交配持续时间(11.00±0.75 min),与初次交配雄虫和有交配经历雌虫的时间(12.12±0.67 min)无显著差异(P0.05)。(3)随温度升高意大利蝗的交配持续时间缩短,27℃时交配持续时间最长(15.93±2.25 min),且与36℃、42℃时的时间差异显著(P0.05),42℃时的交配持续时间最短,为6.01±0.43 min,与36℃时的时间(7.47±0.52 min)差异不显著(P0.05)。     

黑翅土白蚁长翅生殖蚁生殖行为及配对方式研究

【目的】研究黑翅土白蚁Odontotermes fomosanus(Shiraki)生殖行为及不同配对方式对新巢发育的影响。【方法】分别对雌虫、雄虫和配对的雌雄成虫生殖行为进行观察。将雌、雄虫组合成9种配对方式,室内建立170个新巢,分析初建巢生长发育状况。【结果】成虫日活动节律的两个高峰期分别位于9:00—10:00和21:00—22:00,交配集中在高峰期进行,交配前雌雄成虫有触角触碰、首尾衔接成环、互相舔食的标志性行为。生殖蚁来源于同巢和异巢的处理组,在召唤、配对、串联、交配和产卵等生殖行为中均存在差异,来源于异巢的生殖蚁,其配对时间显著长于同巢(P<0.05)。未经分飞的成虫可交配、产卵且成功孵化,3个月后,新巢死亡率为0.61%~0.99%,而分飞蚁新建巢的死亡率为0.22%~0.58%。孤雌生殖可产卵,但卵不能孵化。【结论】成虫的生殖行为有两个高峰期;远亲交配分飞蚁新建巢的生存竞争力最强。     

4. ONE YEAR'S CENSUS AND STUDY OF BIRDS IN 2½ ACRES OF ALEANY BUSHVELD. (Part 2.) April, 1945, to March, 1946

Hooded Vultures Necrosyrtes monachus are critically endangered but little is known of their year-round use of nests or whether other species usurp Hooded Vulture nest sites. We investigated visitation rates by Hooded Vultures and other species (including potential nest predators and usurpers) to examine their effect on Hooded Vulture breeding success. We present observations of 33 species recorded by camera traps at 12 Hooded Vulture nests over a total of 93 nest-months (2 095 nest-days). Several pairs of Hooded Vultures visited their nests regularly during the non-breeding season, some adding nesting material, highlighting that pairs visited their nest(s) year round. Egyptian Geese Alopochen aegyptiaca, potential usurpers of raptor nests, were present at occupied and unoccupied Hooded Vulture nests, but we recorded no usurpation of nests by Egyptian Geese and they had no impact on vulture breeding success. Hooded Vulture breeding failure was linked to two species only: camera-trap imagery recorded one case of predation of a vulture egg by a Chacma Baboon Papio ursinus, and one case of a Martial Eagle Polemaetus bellicosus predating a vulture nestling. We recommend expanding the Hooded Vulture nest monitoring programme to include more pairs.     

Absence from the nest due to human disturbance induces higher nest predation risk than natural recesses in Common Eiders Somateria mollissima

Human disturbance of nesting birds may cause reduced breeding success. It is therefore necessary to assess the impact of disturbance to identify steps that minimize negative impacts. We carried out a study of nesting success at two adjacent colonies of Common Eider Somateria mollissima on the islands of Grindøya and Håkøya in northern Norway between 2006 and 2011. Over the study period, nesting success was consistently higher on Håkøya (69–82%) than on Grindøya (35–60%). Between 2009 and 2011 we used camera monitoring of individual nests to identify determinants of nest survival and predation, focusing in particular on the effect of departures from the nest due to human disturbance, which differed between the colonies due to a long‐term research project on Grindøya. Overall, absence of Common Eiders from nests due to disturbance increased the predation risk by a factor of 6.42 for an increase of one additional daily disturbance. In contrast, absence due to natural recesses did not increase nest losses. Under high levels of human disturbance, camera monitoring indicated that the main cause of breeding failure was predation, primarily by Hooded Crows Corvus cornix, but also to some extent Great Black‐backed Gulls Larus marinus. The presence of cameras did not increase the predation risk. Both the presence of researchers and the sight of Common Eider females conspicuously departing from nests are likely to have provided cues to these predators. We suggest management trials to reduce nesting disturbance through the guarding of unoccupied nests to mitigate the effects of human disturbance on reproductive success.     

Nocturnal nest predation: a potential obstacle to recovery of a Florida Scrub-Jay population

ABSTRACT.   Population declines among birds are often linked to habitat change and associated increases in nest predation rates. In species of conservation concern identifying nest predators is an important first step in developing management strategies to mitigate low nesting success caused by depredation. Because predator composition varies geographically and with landscape factors habitat restoration may need to be tailored to reduce locally important predators. We used miniature video cameras to identify nest predators in a population of Florida Scrub-Jays ( Aphelocoma coerulescens ) significant to conservation. At 22 nests we observed 25 predation events; 22 (88%) of these events were nocturnal. Yellow rat snakes ( Elaphe obsoleta ) had the highest daily predation rate and accounted for 76% of egg and nestling losses. Florida Scrub-Jays are vulnerable to nocturnal nest predation because their vigilance behavior is ineffective against nocturnal predators, breeders cannot defend against nocturnal predators, and brooding females are at risk of being killed by nocturnal predators. If current habitat restoration efforts do not reduce numbers of yellow rat snakes and improve scrub-jay nesting success, management actions to reduce populations of nocturnal snakes may need to be considered.     

Do alien predators pose a particular risk to duck nests in Northern Europe? Results from an artificial nest experiment

Several alien predator species have spread widely in Europe during the last five decades and pose a potential enhanced risk to native nesting ducks and their eggs. Because predation is an important factor limiting Northern Hemisphere duck nest survival, we ask the question, do alien species increase the nest loss risk to ground nesting ducks? We created 418 artificial duck nests in low densities around inland waters in Finland and Denmark during 2017–2019 and monitored them for seven days after construction using wildlife cameras to record whether alien species visit and prey on the nests more often than native species. We sampled various duck breeding habitats from eutrophic agricultural lakes and wetlands to oligotrophic lakes and urban environments. The results differed between habitats and the two countries, which likely reflect the local population densities of the predator species. The raccoon dog (Nyctereutes procyonoides), an alien species, was the most common mammalian nest visitor in all habitats and its occurrence reduced nest survival. Only in wetland habitats was the native red fox (Vulpes vulpes) an equally common nest visitor, where another alien species, the American mink (Neovison vison), also occurred among nest visitors. Although cautious about concluding too much from visitations to artificial nests, these results imply that duck breeding habitats in Northern Europe already support abundant and effective alien nest predators, whose relative frequency of visitation to artificial nests suggest that they potentially add to the nest predation risk to ducks over native predators.

     

Snake predation on North American bird nests: culprits,patterns and future directions

Predation is the leading cause of nest failure for most birds. Thus, for ornithologists interested in the causes and consequences of variation in nest success, knowing the identity and understanding the behavior of dominant nest predators is likely to be important. Video documentation of nests has shown that snakes are frequent predators. Here we reviewed 53 North American studies that used nest cameras and used these data to identify broad patterns in snake predation. Snakes accounted for 26% (range: 0–90%) of recorded predation events, with values exceeding 35% in a third of studies. Snakes were more frequent nest predators at lower latitudes and less frequent in forested habitat relative to other nest predators. Although 12 species of snakes have been identified as nest predators, ratsnakes Elaphe obsoleta, corn snakes E. guttata and fox snakes E. vulpina were the most frequent, accounting for > 70% of all recorded nest predation events by snakes and have been documented preying on nests in 30–65% of studies conducted within their geographic ranges. Endotherm‐specialist snakes (Elaphe and Pituophis genera) were more likely to depredate nests in forests and the canopy relative to other snakes, due to their affinity for edge habitat. Predation by only ratsnakes and corn snakes was predominantly nocturnal and only ratsnakes were more likely to prey on nests during the nestling stage. Snakes were not identified to species in over 30% of predation events, underlining the need for more complete reporting of results. A review of research to date suggests the best approach to investigating factors that bring snakes and nests into contact involves combining nesting studies with radio tracking of locally important snake nest predators.     

Repeatability of nest predation in passerines depends on predator species and time scale

It has been proposed that some specific locations of bird's nests have higher intrinsic chances of being depredated than other locations. This predicts that fates of consecutive nesting attempts at the same site should be repeatable. We used 20 pairs of old thrush nests to simulate repeated nesting attempts at the same sites, both within and between breeding seasons (n=40  sites×2  trials×2  years=160). Each nest was monitored by a camera to record multiple predation events and to identify predators. Predation by all predator species was repeatable during a 15-day trial. Predation by principal predators (jay Garrulus glandarius , marten Martes martes / foina ) and total predation (all species combined) was not correlated within pairs of simultaneously exposed nests or within samples of nests from particular study plot, and not repeatable for individual nests between-trials or between-years. These findings suggest short-term effect of predator memory causing revisitation of previously depredated nests during a current nesting trial (all predators); do not support an effect of nest site features on multiple nest discoveries and/or an effect of nest location on repeated random encounters with the same nest (principal predators). Long-term repeatability and correlation within pairs of simultaneously exposed nests was detectable only in occasional predators (great spotted woodpecker Dendrocopos major , possibly also squirrel Sciurus vulgaris ), which suggests effect of nest location combined with site fidelity and individual foraging specialization of these predators. We conclude that repeatability of nest predation depends on the time scale considered and the local predator community. We caution against spurious findings of repeatable nest predation resulting simply from statistical properties of correlation in binary data (nest fates).     

Successive nest building and polygyny of Fan-tailed Warblers Cisticola juncidis

The polygynous mating system of the Fan-tailed Warbler Cisticola juqcidis was investigated between 1978 and 1981. The male warbler builds many nests unaided; however, he has no more than one active vacant nest for courting at any time. Nest building lasted from April until August. After completing the outer fabric of a nest, the male advertised it and led a female to the nest site by a unique invitation flight. On average a male built 6.5 nests during one breeding season and three of them were accepted by females. The most successful male completed 18 nests, and mated with 11 females. Out of a total of 111 males which established a territory, 30 had no mate, 14 were monogamous, and the rest were polygynous. About 50 to 70% males were polygynous over the four years. The sex ratio varied from 1.41:1 to 2.17:1 (females: male) in the breeding population. It was partly caused by the presence of 'floating males'. After the completion of the outer fabric of the nest, the male warbler did not take any further role in nesting and caring for young.
The polygynous mating system of the Fan-tailed Warbler is characterized by successive nest building. Its extreme development results from the long breeding period and the male having no role in parental care.     

Predation of Lapwing Vanellus vanellus nests on lowland wet grassland in England and Wales: effects of nest density, habitat and predator abundance

There is concern that predation of Lapwing Vanellus vanellus nests may create additional pressure on declining populations of this species in Europe. At seven sites in England and Wales, daily nest predation rates on 1,390 nests were related to variables using Generalised Linear Mixed Models. The strongest predictor was Lapwing nest density (number of nests within 100 m): predation rates declined as nest density increased. Since nocturnal species, probably mammals, have been identified as the major predators of Lapwing nests at these sites, these results suggest that Lapwings are able to deter mammalian predators or may settle to nest at high densities in areas with low predation pressure. At the site level, there was no relationship between Lapwing nesting density and fox density, and a positive relationship with Carrion Crow Corvus corone nesting density. There was a weaker effect of distance to field boundary: nests closer to boundaries were more likely to be predated. Weak interactive effects between crow density and both nest visibility and distance to vantage point were identified in models using a reduced subset of nests. These were counter-intuitive, did not persist in the larger data set, and do not have obvious explanations. If Lapwings nesting at high density are able to deter predators, there are implications for land management. Smaller areas could be managed within potential breeding habitat to encourage Lapwings to nest in dense colonies. Selection of larger fields for such management, where nests could be located far from the field boundary should improve the value of such measures.     

It’s a dog-eat-croc world: dingo predation on the nests of freshwater crocodiles in tropical Australia

Predation on eggs is an important source of mortality for many long-lived organisms, but causes of egg mortality from specific predators remain poorly known in most cases. Understanding the identity of predators, and the rates and determinants of their effects on a cohort of recruits, can provide a valuable background for attempts to exploit, control or conserve populations. We used remotely triggered cameras to study predation on the nests of freshwater crocodiles (Crocodylus johnstoni) inhabiting Lake Argyle, in tropical Australia. We also supplemented our work on natural crocodile nests with artificial nests. Overall, 80 of 111 natural nests were opened by predators, and predation occurred throughout the study period (7 weeks). Unlike in other parts of the species’ range, most nest-robbers were dingoes (Canis lupus dingo, responsible for 98% of all predator visits in the northern sites, and 54% in the Ord River site), with minimal additional predation by reptiles and birds. Contrary to expectation, rates of nest predation were not influenced by spatial clumping of nests: the probability of predation per nest did not change with total numbers of nests laid in an area, and artificially aggregated versus dispersed nests experienced similar levels of predation. Nest vulnerability was linked to abiotic features including slope of surrounding banks, compactness of nesting substrate, and distance from the nearest forest. Abundant aquatic food resources support a large crocodile population, but a lack of suitable nest-sites forces the crocodiles to concentrate nesting in small areas readily accessible to wide-ranging nest predators. Collectively, our results suggest that distinctive attributes of the lakeside landscape alter predator guilds and fashion unique predator–prey interactions.     

Behavior of adult and young grassland songbirds at fledging

The behavior of adults and young at the time of fledging is one of the least understood aspects of the breeding ecology of birds. Current hypotheses propose that fledging occurs either as a result of parent‐offspring conflict or nestling choice. We used video recordings to monitor the behavior of nestling and adult grassland songbirds at the time of fledging. We observed 525 nestlings from 166 nests of 15 bird species nesting in grasslands of Alberta, Canada, and Wisconsin, USA. Overall, 78% of nestlings used terrestrial locomotion for fledging and 22% used wing‐assisted locomotion. Species varied in propensity for using wing‐assisted locomotion when fledging, with nestling Grasshopper Sparrows (Ammodramus savannarum) and Henslow's Sparrows (Centronyx henslowii) often doing so (47% of fledgings) and nestling Song Sparrows (Melospiza melodia), Common Yellowthroats (Geothlypis trichas), and Chestnut‐collared Longspurs (Calcarius ornatus) rarely doing so (3.5% of fledgings). For 390 fledging events at 127 nests, camera placement allowed adults near nests to be observed. Of these, most young fledged (81.5%) when no adult was present at nests. Of 72 fledging events that occurred when an adult was either at or approaching a nest, 49 (68.1%) involved feeding. Of those 49 fledgings, 30 (62.1%) occurred when one or more nestlings jumped or ran from nests to be fed as an adult approached nests. The low probability of nestlings fledging while an adult was at nests, and the tendency of young to jump or run from nests when adults did approach nests with food minimize opportunities for parents to withhold food to motivate nestlings to fledge. These results suggest that the nestling choice hypothesis best explains fledging by nestlings of ground‐nesting grassland songbirds, and fledging results in families shifting from being place‐based to being mobile and spatially dispersed.